enable lint cast_nullable_to_non_nullable (#67629)

analysis_options.yaml

@@ -95,6 +95,7 @@ linter:
     - camel_case_types
     - cancel_subscriptions
     # - cascade_invocations # not yet tested
+    - cast_nullable_to_non_nullable
     # - close_sinks # not reliable enough
     # - comment_references # blocked on https://github.com/flutter/flutter/issues/20765
     # - constant_identifier_names # needs an opt-out https://github.com/dart-lang/linter/issues/204

packages/flutter/lib/src/cupertino/action_sheet.dart

@@ -704,13 +704,13 @@ class _RenderCupertinoAlert extends RenderBox {
     // Set the position of the actions box to sit at the bottom of the alert.
     // The content box defaults to the top left, which is where we want it.
     assert(actionsSection!.parentData is MultiChildLayoutParentData);
-    final MultiChildLayoutParentData actionParentData = actionsSection!.parentData as MultiChildLayoutParentData;
+    final MultiChildLayoutParentData actionParentData = actionsSection!.parentData! as MultiChildLayoutParentData;
     actionParentData.offset = Offset(0.0, contentSize.height + dividerThickness);
   }
 
   @override
   void paint(PaintingContext context, Offset offset) {
-    final MultiChildLayoutParentData contentParentData = contentSection!.parentData as MultiChildLayoutParentData;
+    final MultiChildLayoutParentData contentParentData = contentSection!.parentData! as MultiChildLayoutParentData;
     contentSection!.paint(context, offset + contentParentData.offset);
 
     final bool hasDivider = contentSection!.size.height > 0.0 && actionsSection!.size.height > 0.0;
@@ -718,7 +718,7 @@ class _RenderCupertinoAlert extends RenderBox {
       _paintDividerBetweenContentAndActions(context.canvas, offset);
     }
 
-    final MultiChildLayoutParentData actionsParentData = actionsSection!.parentData as MultiChildLayoutParentData;
+    final MultiChildLayoutParentData actionsParentData = actionsSection!.parentData! as MultiChildLayoutParentData;
     actionsSection!.paint(context, offset + actionsParentData.offset);
   }
 
@@ -736,8 +736,8 @@ class _RenderCupertinoAlert extends RenderBox {
 
   @override
   bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
-    final MultiChildLayoutParentData contentSectionParentData = contentSection!.parentData as MultiChildLayoutParentData;
+    final MultiChildLayoutParentData contentSectionParentData = contentSection!.parentData! as MultiChildLayoutParentData;
-    final MultiChildLayoutParentData actionsSectionParentData = actionsSection!.parentData as MultiChildLayoutParentData;
+    final MultiChildLayoutParentData actionsSectionParentData = actionsSection!.parentData! as MultiChildLayoutParentData;
     return result.addWithPaintOffset(
              offset: contentSectionParentData.offset,
              position: position,
@@ -977,7 +977,7 @@ class _ActionButtonParentDataWidget extends ParentDataWidget<_ActionButtonParent
   @override
   void applyParentData(RenderObject renderObject) {
     assert(renderObject.parentData is _ActionButtonParentData);
-    final _ActionButtonParentData parentData = renderObject.parentData as _ActionButtonParentData;
+    final _ActionButtonParentData parentData = renderObject.parentData! as _ActionButtonParentData;
     if (parentData.isPressed != isPressed) {
       parentData.isPressed = isPressed;
 
@@ -1232,7 +1232,7 @@ class _RenderCupertinoAlertActions extends RenderBox
       );
 
       assert(child.parentData is MultiChildLayoutParentData);
-      final MultiChildLayoutParentData parentData = child.parentData as MultiChildLayoutParentData;
+      final MultiChildLayoutParentData parentData = child.parentData! as MultiChildLayoutParentData;
       parentData.offset = Offset(0.0, verticalOffset);
 
       verticalOffset += child.size.height;
@@ -1274,13 +1274,13 @@ class _RenderCupertinoAlertActions extends RenderBox
     RenderBox? prevChild;
     while (child != null) {
       assert(child.parentData is _ActionButtonParentData);
-      final _ActionButtonParentData currentButtonParentData = child.parentData as _ActionButtonParentData;
+      final _ActionButtonParentData currentButtonParentData = child.parentData! as _ActionButtonParentData;
       final bool isButtonPressed = currentButtonParentData.isPressed;
 
       bool isPrevButtonPressed = false;
       if (prevChild != null) {
         assert(prevChild.parentData is _ActionButtonParentData);
-        final _ActionButtonParentData previousButtonParentData = prevChild.parentData as _ActionButtonParentData;
+        final _ActionButtonParentData previousButtonParentData = prevChild.parentData! as _ActionButtonParentData;
         isPrevButtonPressed = previousButtonParentData.isPressed;
       }
 
@@ -1330,7 +1330,7 @@ class _RenderCupertinoAlertActions extends RenderBox
   void _drawButtons(PaintingContext context, Offset offset) {
     RenderBox? child = firstChild;
     while (child != null) {
-      final MultiChildLayoutParentData childParentData = child.parentData as MultiChildLayoutParentData;
+      final MultiChildLayoutParentData childParentData = child.parentData! as MultiChildLayoutParentData;
       context.paintChild(child, childParentData.offset + offset);
       child = childAfter(child);
     }

packages/flutter/lib/src/cupertino/context_menu.dart

@@ -40,7 +40,7 @@ typedef _ContextMenuPreviewBuilderChildless = Widget Function(
 // paintBounds in global coordinates.
 Rect _getRect(GlobalKey globalKey) {
   assert(globalKey.currentContext != null);
-  final RenderBox renderBoxContainer = globalKey.currentContext!.findRenderObject() as RenderBox;
+  final RenderBox renderBoxContainer = globalKey.currentContext!.findRenderObject()! as RenderBox;
   final Offset containerOffset = renderBoxContainer.localToGlobal(
     renderBoxContainer.paintBounds.topLeft,
   );

packages/flutter/lib/src/cupertino/dialog.dart

@@ -714,7 +714,7 @@ class _RenderCupertinoDialog extends RenderBox {
     // Set the position of the actions box to sit at the bottom of the dialog.
     // The content box defaults to the top left, which is where we want it.
     assert(actionsSection!.parentData is BoxParentData);
-    final BoxParentData actionParentData = actionsSection!.parentData as BoxParentData;
+    final BoxParentData actionParentData = actionsSection!.parentData! as BoxParentData;
     actionParentData.offset = Offset(0.0, contentSize.height + dividerThickness);
   }
 
@@ -776,13 +776,13 @@ class _RenderCupertinoDialog extends RenderBox {
     // Set the position of the actions box to sit at the bottom of the dialog.
     // The content box defaults to the top left, which is where we want it.
     assert(actionsSection!.parentData is BoxParentData);
-    final BoxParentData actionParentData = actionsSection!.parentData as BoxParentData;
+    final BoxParentData actionParentData = actionsSection!.parentData! as BoxParentData;
     actionParentData.offset = Offset(0.0, contentSize.height + dividerThickness);
   }
 
   @override
   void paint(PaintingContext context, Offset offset) {
-    final BoxParentData contentParentData = contentSection!.parentData as BoxParentData;
+    final BoxParentData contentParentData = contentSection!.parentData! as BoxParentData;
     contentSection!.paint(context, offset + contentParentData.offset);
 
     final bool hasDivider = contentSection!.size.height > 0.0 && actionsSection!.size.height > 0.0;
@@ -790,7 +790,7 @@ class _RenderCupertinoDialog extends RenderBox {
       _paintDividerBetweenContentAndActions(context.canvas, offset);
     }
 
-    final BoxParentData actionsParentData = actionsSection!.parentData as BoxParentData;
+    final BoxParentData actionsParentData = actionsSection!.parentData! as BoxParentData;
     actionsSection!.paint(context, offset + actionsParentData.offset);
   }
 
@@ -808,8 +808,8 @@ class _RenderCupertinoDialog extends RenderBox {
 
   @override
   bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
-    final BoxParentData contentSectionParentData = contentSection!.parentData as BoxParentData;
+    final BoxParentData contentSectionParentData = contentSection!.parentData! as BoxParentData;
-    final BoxParentData actionsSectionParentData = actionsSection!.parentData as BoxParentData;
+    final BoxParentData actionsSectionParentData = actionsSection!.parentData! as BoxParentData;
     return result.addWithPaintOffset(
              offset: contentSectionParentData.offset,
              position: position,
@@ -1041,7 +1041,7 @@ class _ActionButtonParentDataWidget extends ParentDataWidget<_ActionButtonParent
   @override
   void applyParentData(RenderObject renderObject) {
     assert(renderObject.parentData is _ActionButtonParentData);
-    final _ActionButtonParentData parentData = renderObject.parentData as _ActionButtonParentData;
+    final _ActionButtonParentData parentData = renderObject.parentData! as _ActionButtonParentData;
     if (parentData.isPressed != isPressed) {
       parentData.isPressed = isPressed;
 
@@ -1396,7 +1396,7 @@ class _RenderCupertinoDialogActions extends RenderBox
     RenderBox? currentChild = firstChild;
     while (currentChild != null) {
       assert(currentChild.parentData is _ActionButtonParentData);
-      final _ActionButtonParentData parentData = currentChild.parentData as _ActionButtonParentData;
+      final _ActionButtonParentData parentData = currentChild.parentData! as _ActionButtonParentData;
       if (parentData.isPressed) {
         yield currentChild;
       }
@@ -1408,7 +1408,7 @@ class _RenderCupertinoDialogActions extends RenderBox
     RenderBox? currentChild = firstChild;
     while (currentChild != null) {
       assert(currentChild.parentData is _ActionButtonParentData);
-      final _ActionButtonParentData parentData = currentChild.parentData as _ActionButtonParentData;
+      final _ActionButtonParentData parentData = currentChild.parentData! as _ActionButtonParentData;
       if (parentData.isPressed) {
         return true;
       }
@@ -1582,7 +1582,7 @@ class _RenderCupertinoDialogActions extends RenderBox
 
         // The 2nd button needs to be offset to the right.
         assert(lastChild!.parentData is MultiChildLayoutParentData);
-        final MultiChildLayoutParentData secondButtonParentData = lastChild!.parentData as MultiChildLayoutParentData;
+        final MultiChildLayoutParentData secondButtonParentData = lastChild!.parentData! as MultiChildLayoutParentData;
         secondButtonParentData.offset = Offset(firstChild!.size.width + dividerThickness, 0.0);
 
         // Calculate our size based on the button sizes.
@@ -1613,7 +1613,7 @@ class _RenderCupertinoDialogActions extends RenderBox
         );
 
         assert(child.parentData is MultiChildLayoutParentData);
-        final MultiChildLayoutParentData parentData = child.parentData as MultiChildLayoutParentData;
+        final MultiChildLayoutParentData parentData = child.parentData! as MultiChildLayoutParentData;
         parentData.offset = Offset(0.0, verticalOffset);
 
         verticalOffset += child.size.height;
@@ -1663,7 +1663,7 @@ class _RenderCupertinoDialogActions extends RenderBox
       : Rect.zero;
 
     final List<Rect> pressedButtonRects = _pressedButtons.map<Rect>((RenderBox pressedButton) {
-      final MultiChildLayoutParentData buttonParentData = pressedButton.parentData as MultiChildLayoutParentData;
+      final MultiChildLayoutParentData buttonParentData = pressedButton.parentData! as MultiChildLayoutParentData;
 
       return Rect.fromLTWH(
         offset.dx + buttonParentData.offset.dx,
@@ -1726,13 +1726,13 @@ class _RenderCupertinoDialogActions extends RenderBox
     RenderBox? prevChild;
     while (child != null) {
       assert(child.parentData is _ActionButtonParentData);
-      final _ActionButtonParentData currentButtonParentData = child.parentData as _ActionButtonParentData;
+      final _ActionButtonParentData currentButtonParentData = child.parentData! as _ActionButtonParentData;
       final bool isButtonPressed = currentButtonParentData.isPressed;
 
       bool isPrevButtonPressed = false;
       if (prevChild != null) {
         assert(prevChild.parentData is _ActionButtonParentData);
-        final _ActionButtonParentData previousButtonParentData = prevChild.parentData as _ActionButtonParentData;
+        final _ActionButtonParentData previousButtonParentData = prevChild.parentData! as _ActionButtonParentData;
         isPrevButtonPressed = previousButtonParentData.isPressed;
       }
 
@@ -1782,7 +1782,7 @@ class _RenderCupertinoDialogActions extends RenderBox
   void _drawButtons(PaintingContext context, Offset offset) {
     RenderBox? child = firstChild;
     while (child != null) {
-      final MultiChildLayoutParentData childParentData = child.parentData as MultiChildLayoutParentData;
+      final MultiChildLayoutParentData childParentData = child.parentData! as MultiChildLayoutParentData;
       context.paintChild(child, childParentData.offset + offset);
       child = childAfter(child);
     }

packages/flutter/lib/src/cupertino/nav_bar.dart

@@ -1450,7 +1450,7 @@ class _BackLabel extends StatelessWidget {
     if (specifiedPreviousTitle != null) {
       return _buildPreviousTitleWidget(context, specifiedPreviousTitle, null);
     } else if (route is CupertinoRouteTransitionMixin<dynamic> && !route!.isFirst) {
-      final CupertinoRouteTransitionMixin<dynamic> cupertinoRoute = route as CupertinoRouteTransitionMixin<dynamic>;
+      final CupertinoRouteTransitionMixin<dynamic> cupertinoRoute = route! as CupertinoRouteTransitionMixin<dynamic>;
       // There is no timing issue because the previousTitle Listenable changes
       // happen during route modifications before the ValueListenableBuilder
       // is built.
@@ -1499,7 +1499,7 @@ class _TransitionableNavigationBar extends StatelessWidget {
   final Widget child;
 
   RenderBox get renderBox {
-    final RenderBox box = componentsKeys.navBarBoxKey.currentContext!.findRenderObject() as RenderBox;
+    final RenderBox box = componentsKeys.navBarBoxKey.currentContext!.findRenderObject()! as RenderBox;
     assert(
       box.attached,
       '_TransitionableNavigationBar.renderBox should be called when building '
@@ -1729,7 +1729,7 @@ class _NavigationBarComponentsTransition {
     GlobalKey key, {
     required RenderBox from,
   }) {
-    final RenderBox componentBox = key.currentContext!.findRenderObject() as RenderBox;
+    final RenderBox componentBox = key.currentContext!.findRenderObject()! as RenderBox;
     assert(componentBox.attached);
 
     return RelativeRect.fromRect(
@@ -1756,8 +1756,8 @@ class _NavigationBarComponentsTransition {
   }) {
     final RelativeRect fromRect = positionInTransitionBox(fromKey, from: fromNavBarBox);
 
-    final RenderBox fromBox = fromKey.currentContext!.findRenderObject() as RenderBox;
+    final RenderBox fromBox = fromKey.currentContext!.findRenderObject()! as RenderBox;
-    final RenderBox toBox = toKey.currentContext!.findRenderObject() as RenderBox;
+    final RenderBox toBox = toKey.currentContext!.findRenderObject()! as RenderBox;
 
     // We move a box with the size of the 'from' render object such that its
     // upper left corner is at the upper left corner of the 'to' render object.
@@ -2038,7 +2038,7 @@ class _NavigationBarComponentsTransition {
     // If it's the first page with a back chevron, shift in slightly from the
     // right.
     if (bottomBackChevron == null) {
-      final RenderBox topBackChevronBox = topComponents.backChevronKey.currentContext!.findRenderObject() as RenderBox;
+      final RenderBox topBackChevronBox = topComponents.backChevronKey.currentContext!.findRenderObject()! as RenderBox;
       from = to.shift(
         Offset(
           forwardDirection * topBackChevronBox.size.width * 2.0,

packages/flutter/lib/src/cupertino/scrollbar.dart

@@ -551,8 +551,8 @@ bool _hitTestInteractive(GlobalKey customPaintKey, Offset offset) {
     return false;
   }
   final CustomPaint customPaint = customPaintKey.currentContext!.widget as CustomPaint;
-  final ScrollbarPainter painter = customPaint.foregroundPainter as ScrollbarPainter;
+  final ScrollbarPainter painter = customPaint.foregroundPainter! as ScrollbarPainter;
-  final RenderBox renderBox = customPaintKey.currentContext!.findRenderObject() as RenderBox;
+  final RenderBox renderBox = customPaintKey.currentContext!.findRenderObject()! as RenderBox;
   final Offset localOffset = renderBox.globalToLocal(offset);
   return painter.hitTestInteractive(localOffset);
 }

packages/flutter/lib/src/cupertino/segmented_control.dart

@@ -544,7 +544,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = firstChild;
     double minWidth = 0.0;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childWidth = child.getMinIntrinsicWidth(height);
       minWidth = math.max(minWidth, childWidth);
       child = childParentData.nextSibling;
@@ -557,7 +557,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = firstChild;
     double maxWidth = 0.0;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childWidth = child.getMaxIntrinsicWidth(height);
       maxWidth = math.max(maxWidth, childWidth);
       child = childParentData.nextSibling;
@@ -570,7 +570,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = firstChild;
     double minHeight = 0.0;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childHeight = child.getMinIntrinsicHeight(width);
       minHeight = math.max(minHeight, childHeight);
       child = childParentData.nextSibling;
@@ -583,7 +583,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = firstChild;
     double maxHeight = 0.0;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childHeight = child.getMaxIntrinsicHeight(width);
       maxHeight = math.max(maxHeight, childHeight);
       child = childParentData.nextSibling;
@@ -607,7 +607,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = leftChild;
     double start = 0.0;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       final Offset childOffset = Offset(start, 0.0);
       childParentData.offset = childOffset;
       final Rect childRect = Rect.fromLTWH(start, 0.0, child.size.width, child.size.height);
@@ -692,7 +692,7 @@ class _RenderSegmentedControl<T> extends RenderBox
   void _paintChild(PaintingContext context, Offset offset, RenderBox child, int childIndex) {
     assert(child != null);
 
-    final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+    final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
 
     context.canvas.drawRRect(
       childParentData.surroundingRect!.shift(offset),
@@ -716,7 +716,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     assert(position != null);
     RenderBox? child = lastChild;
     while (child != null) {
-      final _SegmentedControlContainerBoxParentData childParentData = child.parentData as _SegmentedControlContainerBoxParentData;
+      final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
       if (childParentData.surroundingRect!.contains(position)) {
         return result.addWithPaintOffset(
           offset: childParentData.offset,

packages/flutter/lib/src/cupertino/sliding_segmented_control.dart

@@ -764,7 +764,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxMinChildWidth = 0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childWidth = child.getMinIntrinsicWidth(height);
       maxMinChildWidth = math.max(maxMinChildWidth, childWidth);
       child = childParentData.nextSibling;
@@ -778,7 +778,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxMaxChildWidth = 0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childWidth = child.getMaxIntrinsicWidth(height);
       maxMaxChildWidth = math.max(maxMaxChildWidth, childWidth);
       child = childParentData.nextSibling;
@@ -792,7 +792,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxMinChildHeight = 0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childHeight = child.getMinIntrinsicHeight(width);
       maxMinChildHeight = math.max(maxMinChildHeight, childHeight);
       child = childParentData.nextSibling;
@@ -806,7 +806,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     double maxMaxChildHeight = 0;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       final double childHeight = child.getMaxIntrinsicHeight(width);
       maxMaxChildHeight = math.max(maxMaxChildHeight, childHeight);
       child = childParentData.nextSibling;
@@ -867,7 +867,7 @@ class _RenderSegmentedControl<T> extends RenderBox
 
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       final Offset childOffset = Offset(start, 0);
       childParentData.offset = childOffset;
       start += child.size.width + _kSeparatorWidth + _kSeparatorInset.horizontal;
@@ -897,7 +897,7 @@ class _RenderSegmentedControl<T> extends RenderBox
       final RenderBox selectedChild = children[highlightedIndex!];
 
       final _SegmentedControlContainerBoxParentData childParentData =
-        selectedChild.parentData as _SegmentedControlContainerBoxParentData;
+        selectedChild.parentData! as _SegmentedControlContainerBoxParentData;
       final Rect unscaledThumbTargetRect = _kThumbInsets.inflateRect(childParentData.offset & selectedChild.size);
 
       // Update related Tweens before animation update phase.
@@ -958,7 +958,7 @@ class _RenderSegmentedControl<T> extends RenderBox
   void _paintSeparator(PaintingContext context, Offset offset, RenderBox child) {
     assert(child != null);
     final _SegmentedControlContainerBoxParentData childParentData =
-      child.parentData as _SegmentedControlContainerBoxParentData;
+      child.parentData! as _SegmentedControlContainerBoxParentData;
 
     final Paint paint = Paint();
 
@@ -981,7 +981,7 @@ class _RenderSegmentedControl<T> extends RenderBox
   void _paintChild(PaintingContext context, Offset offset, RenderBox child, int childIndex) {
     assert(child != null);
     final _SegmentedControlContainerBoxParentData childParentData =
-      child.parentData as _SegmentedControlContainerBoxParentData;
+      child.parentData! as _SegmentedControlContainerBoxParentData;
     context.paintChild(child, childParentData.offset + offset);
   }
 
@@ -1023,7 +1023,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     RenderBox? child = lastChild;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
-        child.parentData as _SegmentedControlContainerBoxParentData;
+        child.parentData! as _SegmentedControlContainerBoxParentData;
       if ((childParentData.offset & child.size).contains(position)) {
         return result.addWithPaintOffset(
           offset: childParentData.offset,

packages/flutter/lib/src/cupertino/text_field.dart

@@ -100,7 +100,7 @@ class _CupertinoTextFieldSelectionGestureDetectorBuilder extends TextSelectionGe
     // this handler. If the clear button widget recognizes the up event,
     // then do not handle it.
     if (_state._clearGlobalKey.currentContext != null) {
-      final RenderBox renderBox = _state._clearGlobalKey.currentContext!.findRenderObject() as RenderBox;
+      final RenderBox renderBox = _state._clearGlobalKey.currentContext!.findRenderObject()! as RenderBox;
       final Offset localOffset = renderBox.globalToLocal(details.globalPosition);
       if (renderBox.hitTest(BoxHitTestResult(), position: localOffset)) {
         return;
@@ -905,7 +905,7 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with Restoratio
     final Color? decorationColor = CupertinoDynamicColor.resolve(widget.decoration?.color, context);
 
     final BoxBorder? border = widget.decoration?.border;
-    Border resolvedBorder = border as Border;
+    Border? resolvedBorder = border as Border?;
     if (border is Border) {
       BorderSide resolveBorderSide(BorderSide side) {
         return side == BorderSide.none

packages/flutter/lib/src/cupertino/text_selection.dart

@@ -324,7 +324,7 @@ class _ToolbarRenderBox extends RenderShiftedBox {
       .loosen();
 
     child!.layout(heightConstraint.enforce(enforcedConstraint), parentUsesSize: true,);
-    final _ToolbarParentData childParentData = child!.parentData as _ToolbarParentData;
+    final _ToolbarParentData childParentData = child!.parentData! as _ToolbarParentData;
 
     // The local x-coordinate of the center of the toolbar.
     final double lowerBound = child!.size.width/2 + _kToolbarScreenPadding;
@@ -337,7 +337,7 @@ class _ToolbarRenderBox extends RenderShiftedBox {
 
   // The path is described in the toolbar's coordinate system.
   Path _clipPath() {
-    final _ToolbarParentData childParentData = child!.parentData as _ToolbarParentData;
+    final _ToolbarParentData childParentData = child!.parentData! as _ToolbarParentData;
     final Path rrect = Path()
       ..addRRect(
         RRect.fromRectAndRadius(
@@ -370,7 +370,7 @@ class _ToolbarRenderBox extends RenderShiftedBox {
       return;
     }
 
-    final _ToolbarParentData childParentData = child!.parentData as _ToolbarParentData;
+    final _ToolbarParentData childParentData = child!.parentData! as _ToolbarParentData;
     context.pushClipPath(
       needsCompositing,
       offset + childParentData.offset,
@@ -400,7 +400,7 @@ class _ToolbarRenderBox extends RenderShiftedBox {
         ..strokeWidth = 2.0
         ..style = PaintingStyle.stroke;
 
-      final _ToolbarParentData childParentData = child!.parentData as _ToolbarParentData;
+      final _ToolbarParentData childParentData = child!.parentData! as _ToolbarParentData;
       context.canvas.drawPath(_clipPath().shift(offset + childParentData.offset), _debugPaint!);
       return true;
     }());
@@ -789,11 +789,11 @@ class _CupertinoTextSelectionToolbarItemsElement extends RenderObjectElement {
   @override
   void moveRenderObjectChild(RenderObject child, IndexedSlot<Element> oldSlot, IndexedSlot<Element> newSlot) {
     assert(child.parent == renderObject);
-    renderObject.move(child as RenderBox, after: newSlot.value.renderObject as RenderBox);
+    renderObject.move(child as RenderBox, after: newSlot.value.renderObject as RenderBox?);
   }
 
   static bool _shouldPaint(Element child) {
-    return (child.renderObject!.parentData as ToolbarItemsParentData).shouldPaint;
+    return (child.renderObject!.parentData! as ToolbarItemsParentData).shouldPaint;
   }
 
   @override
@@ -986,7 +986,7 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
       i++;
       final RenderBox child = renderObjectChild as RenderBox;
       final ToolbarItemsParentData childParentData =
-          child.parentData as ToolbarItemsParentData;
+          child.parentData! as ToolbarItemsParentData;
       childParentData.shouldPaint = false;
 
       // Skip slotted children and children on pages after the visible page.
@@ -1046,11 +1046,11 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
     // Position page nav buttons.
     if (currentPage > 0) {
       final ToolbarItemsParentData nextButtonParentData =
-          _nextButton!.parentData as ToolbarItemsParentData;
+          _nextButton!.parentData! as ToolbarItemsParentData;
       final ToolbarItemsParentData nextButtonDisabledParentData =
-          _nextButtonDisabled!.parentData as ToolbarItemsParentData;
+          _nextButtonDisabled!.parentData! as ToolbarItemsParentData;
       final ToolbarItemsParentData backButtonParentData =
-          _backButton!.parentData as ToolbarItemsParentData;
+          _backButton!.parentData! as ToolbarItemsParentData;
       // The forward button always shows if there is more than one page, even on
       // the last page (it's just disabled).
       if (page == currentPage) {
@@ -1081,7 +1081,7 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
   void paint(PaintingContext context, Offset offset) {
     visitChildren((RenderObject renderObjectChild) {
       final RenderBox child = renderObjectChild as RenderBox;
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
 
       if (childParentData.shouldPaint) {
         final Offset childOffset = childParentData.offset + offset;
@@ -1103,7 +1103,7 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
       return false;
     }
     final ToolbarItemsParentData childParentData =
-        child.parentData as ToolbarItemsParentData;
+        child.parentData! as ToolbarItemsParentData;
     return result.addWithPaintOffset(
       offset: childParentData.offset,
       position: position,
@@ -1120,7 +1120,7 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
     // The x, y parameters have the top left of the node's box as the origin.
     RenderBox? child = lastChild;
     while (child != null) {
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
 
       // Don't hit test children that aren't shown.
       if (!childParentData.shouldPaint) {
@@ -1199,7 +1199,7 @@ class _CupertinoTextSelectionToolbarItemsRenderBox extends RenderBox with Contai
   void visitChildrenForSemantics(RenderObjectVisitor visitor) {
     visitChildren((RenderObject renderObjectChild) {
       final RenderBox child = renderObjectChild as RenderBox;
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
       if (childParentData.shouldPaint) {
         visitor(renderObjectChild);
       }

packages/flutter/lib/src/foundation/assertions.dart

@@ -591,7 +591,7 @@ class FlutterErrorDetails with Diagnosticable {
       return exception;
     }
     if (exception is AssertionError && exception.message is FlutterError) {
-      return exception.message as FlutterError;
+      return exception.message! as FlutterError;
     }
     return null;
   }

packages/flutter/lib/src/material/about.dart

@@ -501,7 +501,7 @@ class _LicensePageState extends State<LicensePage> {
 
   Widget _packageLicensePage(BuildContext _, Object? args, ScrollController? scrollController) {
     assert(args is _DetailArguments);
-    final _DetailArguments detailArguments = args as _DetailArguments;
+    final _DetailArguments detailArguments = args! as _DetailArguments;
     return _PackageLicensePage(
       packageName: detailArguments.packageName,
       licenseEntries: detailArguments.licenseEntries,

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -187,7 +187,7 @@ class _BottomSheetState extends State<BottomSheet> {
   final GlobalKey _childKey = GlobalKey(debugLabel: 'BottomSheet child');
 
   double get _childHeight {
-    final RenderBox renderBox = _childKey.currentContext!.findRenderObject() as RenderBox;
+    final RenderBox renderBox = _childKey.currentContext!.findRenderObject()! as RenderBox;
     return renderBox.size.height;
   }
 

packages/flutter/lib/src/material/button.dart

@@ -550,7 +550,7 @@ class _RenderInputPadding extends RenderShiftedBox {
       final double height = math.max(child!.size.width, minSize.width);
       final double width = math.max(child!.size.height, minSize.height);
       size = constraints.constrain(Size(height, width));
-      final BoxParentData childParentData = child!.parentData as BoxParentData;
+      final BoxParentData childParentData = child!.parentData! as BoxParentData;
       childParentData.offset = Alignment.center.alongOffset(size - child!.size as Offset);
     } else {
       size = Size.zero;

packages/flutter/lib/src/material/button_bar.dart

@@ -367,7 +367,7 @@ class _RenderButtonBarRow extends RenderFlex {
       }
 
       while (child != null) {
-        final FlexParentData childParentData = child.parentData as FlexParentData;
+        final FlexParentData childParentData = child.parentData! as FlexParentData;
 
         // Lay out the child with the button bar's original constraints, but
         // with minimum width set to zero.

packages/flutter/lib/src/material/button_style_button.dart

@@ -483,7 +483,7 @@ class _RenderInputPadding extends RenderShiftedBox {
       final double height = math.max(child!.size.width, minSize.width);
       final double width = math.max(child!.size.height, minSize.height);
       size = constraints.constrain(Size(height, width));
-      final BoxParentData childParentData = child!.parentData as BoxParentData;
+      final BoxParentData childParentData = child!.parentData! as BoxParentData;
       childParentData.offset = Alignment.center.alongOffset(size - child!.size as Offset);
     } else {
       size = Size.zero;

packages/flutter/lib/src/material/chip.dart

@@ -2128,13 +2128,13 @@ class _RenderChipElement extends RenderObjectElement {
   void _updateRenderObject(RenderObject? child, _ChipSlot slot) {
     switch (slot) {
       case _ChipSlot.avatar:
-        renderObject.avatar = child as RenderBox;
+        renderObject.avatar = child as RenderBox?;
         break;
       case _ChipSlot.label:
-        renderObject.label = child as RenderBox;
+        renderObject.label = child as RenderBox?;
         break;
       case _ChipSlot.deleteIcon:
-        renderObject.deleteIcon = child as RenderBox;
+        renderObject.deleteIcon = child as RenderBox?;
         break;
     }
   }
@@ -2385,7 +2385,7 @@ class _RenderChip extends RenderBox {
 
   static Rect _boxRect(RenderBox? box) => box == null ? Rect.zero : _boxParentData(box).offset & box.size;
 
-  static BoxParentData _boxParentData(RenderBox box) => box.parentData as BoxParentData;
+  static BoxParentData _boxParentData(RenderBox box) => box.parentData! as BoxParentData;
 
   @override
   double computeMinIntrinsicWidth(double height) {
@@ -2907,7 +2907,7 @@ class _LocationAwareInkRippleFactory extends InteractiveInkFeatureFactory {
 
     if (tapIsOnDeleteIcon) {
       final RenderBox currentBox = referenceBox;
-      referenceBox = deleteIconKey.currentContext!.findRenderObject() as RenderBox;
+      referenceBox = deleteIconKey.currentContext!.findRenderObject()! as RenderBox;
       position = referenceBox.globalToLocal(currentBox.localToGlobal(position));
       containedInkWell = false;
     }

packages/flutter/lib/src/material/data_table.dart

@@ -1030,7 +1030,7 @@ class TableRowInkWell extends InkResponse {
         table = table.parent;
       }
       if (table is RenderTable) {
-        final TableCellParentData cellParentData = cell.parentData as TableCellParentData;
+        final TableCellParentData cellParentData = cell.parentData! as TableCellParentData;
         assert(cellParentData.y != null);
         final Rect rect = table.getRowBox(cellParentData.y!);
         // The rect is in the table's coordinate space. We need to change it to the

packages/flutter/lib/src/material/dropdown.dart

@@ -1179,7 +1179,7 @@ class _DropdownButtonState<T> extends State<DropdownButton<T>> with WidgetsBindi
   TextStyle? get _textStyle => widget.style ?? Theme.of(context)!.textTheme.subtitle1;
 
   void _handleTap() {
-    final RenderBox itemBox = context.findRenderObject() as RenderBox;
+    final RenderBox itemBox = context.findRenderObject()! as RenderBox;
     final Rect itemRect = itemBox.localToGlobal(Offset.zero) & itemBox.size;
     final TextDirection? textDirection = Directionality.of(context);
     final EdgeInsetsGeometry menuMargin = ButtonTheme.of(context).alignedDropdown

packages/flutter/lib/src/material/ink_decoration.dart

@@ -255,7 +255,7 @@ class _InkState extends State<Ink> {
         decoration: widget.decoration,
         configuration: createLocalImageConfiguration(context),
         controller: Material.of(context)!,
-        referenceBox: context.findRenderObject() as RenderBox,
+        referenceBox: context.findRenderObject()! as RenderBox,
         onRemoved: _handleRemoved,
       );
     } else {

packages/flutter/lib/src/material/input_decorator.dart

@@ -62,7 +62,7 @@ class _InputBorderTween extends Tween<InputBorder> {
   _InputBorderTween({InputBorder? begin, InputBorder? end}) : super(begin: begin, end: end);
 
   @override
-  InputBorder lerp(double t) => ShapeBorder.lerp(begin, end, t) as InputBorder;
+  InputBorder lerp(double t) => ShapeBorder.lerp(begin, end, t)! as InputBorder;
 }
 
 // Passes the _InputBorderGap parameters along to an InputBorder's paint method.
@@ -919,7 +919,7 @@ class _RenderDecoration extends RenderBox {
 
   static Size _boxSize(RenderBox? box) => box == null ? Size.zero : box.size;
 
-  static BoxParentData _boxParentData(RenderBox box) => box.parentData as BoxParentData;
+  static BoxParentData _boxParentData(RenderBox box) => box.parentData! as BoxParentData;
 
   EdgeInsets get contentPadding => decoration.contentPadding as EdgeInsets;
 

packages/flutter/lib/src/material/list_tile.dart

@@ -1688,7 +1688,7 @@ class _RenderListTile extends RenderBox {
   void paint(PaintingContext context, Offset offset) {
     void doPaint(RenderBox? child) {
       if (child != null) {
-        final BoxParentData parentData = child.parentData as BoxParentData;
+        final BoxParentData parentData = child.parentData! as BoxParentData;
         context.paintChild(child, parentData.offset + offset);
       }
     }
@@ -1705,7 +1705,7 @@ class _RenderListTile extends RenderBox {
   bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
     assert(position != null);
     for (final RenderBox child in _children) {
-      final BoxParentData parentData = child.parentData as BoxParentData;
+      final BoxParentData parentData = child.parentData! as BoxParentData;
       final bool isHit = result.addWithPaintOffset(
         offset: parentData.offset,
         position: position,

packages/flutter/lib/src/material/material.dart

@@ -637,8 +637,7 @@ abstract class InkFeature {
     final List<RenderObject> descendants = <RenderObject>[referenceBox];
     RenderObject node = referenceBox;
     while (node != _controller) {
-      node = node.parent as RenderObject;
+      node = node.parent! as RenderObject;
-      assert(node != null);
       descendants.add(node);
     }
     // determine the transform that gets our coordinate system to be like theirs
@@ -763,17 +762,17 @@ class _MaterialInteriorState extends AnimatedWidgetBaseState<_MaterialInterior>
       _elevation,
       widget.elevation,
       (dynamic value) => Tween<double>(begin: value as double),
-    ) as Tween<double>;
+    ) as Tween<double>?;
     _shadowColor = visitor(
       _shadowColor,
       widget.shadowColor,
       (dynamic value) => ColorTween(begin: value as Color),
-    ) as ColorTween;
+    ) as ColorTween?;
     _border = visitor(
       _border,
       widget.shape,
       (dynamic value) => ShapeBorderTween(begin: value as ShapeBorder),
-    ) as ShapeBorderTween;
+    ) as ShapeBorderTween?;
   }
 
   @override

packages/flutter/lib/src/material/scaffold.dart

@@ -2570,7 +2570,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin {
         clipBehavior: clipBehavior,
       );
     });
-    return _currentBottomSheet as PersistentBottomSheetController<T>;
+    return _currentBottomSheet! as PersistentBottomSheetController<T>;
   }
 
   // Floating Action Button API

packages/flutter/lib/src/material/tabs.dart

@@ -240,7 +240,7 @@ class _TabLabelBarRenderer extends RenderFlex {
     RenderBox? child = firstChild;
     final List<double> xOffsets = <double>[];
     while (child != null) {
-      final FlexParentData childParentData = child.parentData as FlexParentData;
+      final FlexParentData childParentData = child.parentData! as FlexParentData;
       xOffsets.add(childParentData.offset.dx);
       assert(child.parentData == childParentData);
       child = childParentData.nextSibling;

packages/flutter/lib/src/material/text_selection.dart

@@ -550,7 +550,7 @@ class _TextSelectionToolbarItemsRenderBox extends RenderBox with ContainerRender
     });
 
     // Place the navigation button if needed.
-    final ToolbarItemsParentData navButtonParentData = navButton.parentData as ToolbarItemsParentData;
+    final ToolbarItemsParentData navButtonParentData = navButton.parentData! as ToolbarItemsParentData;
     if (_shouldPaintChild(firstChild!, 0)) {
       navButtonParentData.shouldPaint = true;
       if (overflowOpen) {
@@ -588,7 +588,7 @@ class _TextSelectionToolbarItemsRenderBox extends RenderBox with ContainerRender
   void paint(PaintingContext context, Offset offset) {
     visitChildren((RenderObject renderObjectChild) {
       final RenderBox child = renderObjectChild as RenderBox;
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
       if (!childParentData.shouldPaint) {
         return;
       }
@@ -609,7 +609,7 @@ class _TextSelectionToolbarItemsRenderBox extends RenderBox with ContainerRender
     // The x, y parameters have the top left of the node's box as the origin.
     RenderBox? child = lastChild;
     while (child != null) {
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
 
       // Don't hit test children aren't shown.
       if (!childParentData.shouldPaint) {
@@ -637,7 +637,7 @@ class _TextSelectionToolbarItemsRenderBox extends RenderBox with ContainerRender
   void visitChildrenForSemantics(RenderObjectVisitor visitor) {
     visitChildren((RenderObject renderObjectChild) {
       final RenderBox child = renderObjectChild as RenderBox;
-      final ToolbarItemsParentData childParentData = child.parentData as ToolbarItemsParentData;
+      final ToolbarItemsParentData childParentData = child.parentData! as ToolbarItemsParentData;
       if (childParentData.shouldPaint) {
         visitor(renderObjectChild);
       }

packages/flutter/lib/src/material/theme.dart

@@ -254,8 +254,7 @@ class _AnimatedThemeState extends AnimatedWidgetBaseState<AnimatedTheme> {
   @override
   void forEachTween(TweenVisitor<dynamic> visitor) {
     // TODO(ianh): Use constructor tear-offs when it becomes possible, https://github.com/dart-lang/sdk/issues/10659
-    _data = visitor(_data, widget.data, (dynamic value) => ThemeDataTween(begin: value as ThemeData)) as ThemeDataTween;
+    _data = visitor(_data, widget.data, (dynamic value) => ThemeDataTween(begin: value as ThemeData))! as ThemeDataTween;
-    assert(_data != null);
   }
 
   @override

packages/flutter/lib/src/material/time_picker.dart

@@ -1037,7 +1037,7 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
   void _handlePanStart(DragStartDetails details) {
     assert(!_dragging);
     _dragging = true;
-    final RenderBox box = context.findRenderObject() as RenderBox;
+    final RenderBox box = context.findRenderObject()! as RenderBox;
     _position = box.globalToLocal(details.globalPosition);
     _center = box.size.center(Offset.zero);
     _updateThetaForPan();
@@ -1064,7 +1064,7 @@ class _DialState extends State<_Dial> with SingleTickerProviderStateMixin {
   }
 
   void _handleTapUp(TapUpDetails details) {
-    final RenderBox box = context.findRenderObject() as RenderBox;
+    final RenderBox box = context.findRenderObject()! as RenderBox;
     _position = box.globalToLocal(details.globalPosition);
     _center = box.size.center(Offset.zero);
     _updateThetaForPan(roundMinutes: true);

packages/flutter/lib/src/material/time_picker_theme.dart

@@ -272,7 +272,7 @@ class TimePickerThemeData with Diagnosticable {
       helpTextStyle: TextStyle.lerp(a?.helpTextStyle, b?.helpTextStyle, t),
       shape: ShapeBorder.lerp(a?.shape, b?.shape, t),
       hourMinuteShape: ShapeBorder.lerp(a?.hourMinuteShape, b?.hourMinuteShape, t),
-      dayPeriodShape: ShapeBorder.lerp(a?.dayPeriodShape, b?.dayPeriodShape, t) as OutlinedBorder,
+      dayPeriodShape: ShapeBorder.lerp(a?.dayPeriodShape, b?.dayPeriodShape, t) as OutlinedBorder?,
       dayPeriodBorderSide: lerpedBorderSide,
       inputDecorationTheme: t < 0.5 ? a?.inputDecorationTheme : b?.inputDecorationTheme,
     );

packages/flutter/lib/src/widgets/navigator.dart

@@ -4978,7 +4978,7 @@ class NavigatorState extends State<Navigator> with TickerProviderStateMixin, Res
     return _history.cast<_RouteEntry?>().firstWhere(
       (_RouteEntry? entry) => entry!.restorationId == id,
       orElse: () => null,
-    )?.route as Route<T>;
+    )?.route as Route<T>?;
   }
 
   int get _userGesturesInProgress => _userGesturesInProgressCount;
@@ -5208,8 +5208,7 @@ class _AnonymousRestorationInformation extends _RestorationInformation {
 
   factory _AnonymousRestorationInformation.fromSerializableData(List<Object> data) {
     assert(data.length > 1);
-    final RestorableRouteBuilder routeBuilder = ui.PluginUtilities.getCallbackFromHandle(ui.CallbackHandle.fromRawHandle(data[1] as int)) as RestorableRouteBuilder;
+    final RestorableRouteBuilder routeBuilder = ui.PluginUtilities.getCallbackFromHandle(ui.CallbackHandle.fromRawHandle(data[1] as int))! as RestorableRouteBuilder;
-    assert(routeBuilder != null);
     return _AnonymousRestorationInformation(
       restorationScopeId: data[0] as int,
       routeBuilder: routeBuilder,

packages/flutter/test/cupertino/colors_test.dart

@@ -505,7 +505,7 @@ void main() {
     setUp(() { color = null; });
 
     testWidgets('dynamic color works in cupertino override theme', (WidgetTester tester) async {
-      final CupertinoDynamicColor Function() typedColor = () => color as CupertinoDynamicColor;
+      final CupertinoDynamicColor Function() typedColor = () => color! as CupertinoDynamicColor;
 
       await tester.pumpWidget(
         MaterialApp(

packages/flutter/test/cupertino/context_menu_action_test.dart

@@ -40,7 +40,7 @@ void main() {
     );
     expect(finder, findsOneWidget);
     final Container container = tester.widget(finder);
-    return container.decoration as BoxDecoration;
+    return container.decoration! as BoxDecoration;
   }
 
   TextStyle _getTextStyle(WidgetTester tester) {

packages/flutter/test/cupertino/nav_bar_test.dart

@@ -390,8 +390,8 @@ void main() {
     List<Element> titles = tester.elementList(find.text('Title'))
         .toList()
         ..sort((Element a, Element b) {
-          final RenderParagraph aParagraph = a.renderObject as RenderParagraph;
+          final RenderParagraph aParagraph = a.renderObject! as RenderParagraph;
-          final RenderParagraph bParagraph = b.renderObject as RenderParagraph;
+          final RenderParagraph bParagraph = b.renderObject! as RenderParagraph;
           return aParagraph.text.style!.fontSize!.compareTo(bParagraph.text.style!.fontSize!);
         });
 
@@ -415,8 +415,8 @@ void main() {
     titles = tester.elementList(find.text('Title'))
         .toList()
         ..sort((Element a, Element b) {
-          final RenderParagraph aParagraph = a.renderObject as RenderParagraph;
+          final RenderParagraph aParagraph = a.renderObject! as RenderParagraph;
-          final RenderParagraph bParagraph = b.renderObject as RenderParagraph;
+          final RenderParagraph bParagraph = b.renderObject! as RenderParagraph;
           return aParagraph.text.style!.fontSize!.compareTo(bParagraph.text.style!.fontSize!);
         });
 

packages/flutter/test/cupertino/route_test.dart

@@ -83,8 +83,8 @@ void main() {
     final List<Element> titles = tester.elementList(find.text('An iPod'))
         .toList()
         ..sort((Element a, Element b) {
-          final RenderParagraph aParagraph = a.renderObject as RenderParagraph;
+          final RenderParagraph aParagraph = a.renderObject! as RenderParagraph;
-          final RenderParagraph bParagraph = b.renderObject as RenderParagraph;
+          final RenderParagraph bParagraph = b.renderObject! as RenderParagraph;
           return aParagraph.text.style!.fontSize!.compareTo(
             bParagraph.text.style!.fontSize!
           );

packages/flutter/test/cupertino/sliding_segmented_control_test.dart

@@ -301,7 +301,7 @@ void main() {
     final BoxDecoration decoration = tester.widget<Container>(find.descendant(
       of: find.byType(UnconstrainedBox),
       matching: find.byType(Container),
-    )).decoration as BoxDecoration;
+    )).decoration! as BoxDecoration;
 
     expect(getRenderSegmentedControl(tester).thumbColor.value, CupertinoColors.systemGreen.color.value);
     expect(decoration.color!.value, CupertinoColors.systemRed.color.value);
@@ -312,7 +312,7 @@ void main() {
     final BoxDecoration decorationDark = tester.widget<Container>(find.descendant(
       of: find.byType(UnconstrainedBox),
       matching: find.byType(Container),
-    )).decoration as BoxDecoration;
+    )).decoration! as BoxDecoration;
 
 
     expect(getRenderSegmentedControl(tester).thumbColor.value, CupertinoColors.systemGreen.darkColor.value);

packages/flutter/test/foundation/diagnostics_json_test.dart

@@ -76,7 +76,7 @@ void main() {
     test('subtreeDepth 1', () {
       final Map<String, Object?> result = testTree.toDiagnosticsNode().toJsonMap(const DiagnosticsSerializationDelegate(subtreeDepth: 1));
       expect(result.containsKey('properties'), isFalse);
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children[0].containsKey('children'), isFalse);
       expect(children[1].containsKey('children'), isFalse);
       expect(children[2].containsKey('children'), isFalse);
@@ -85,7 +85,7 @@ void main() {
     test('subtreeDepth 5', () {
       final Map<String, Object?> result = testTree.toDiagnosticsNode().toJsonMap(const DiagnosticsSerializationDelegate(subtreeDepth: 5));
       expect(result.containsKey('properties'), isFalse);
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children[0]['children'], hasLength(0));
       expect(children[1]['children'], hasLength(3));
       expect(children[2]['children'], hasLength(0));
@@ -103,7 +103,7 @@ void main() {
         subtreeDepth: 1,
       ));
       expect(result['properties'], hasLength(7));
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(3));
       expect(children[0]['properties'], hasLength(0));
       expect(children[1]['properties'], hasLength(2));
@@ -119,11 +119,11 @@ void main() {
         },
       ));
       expect(result['foo'], isTrue);
-      final List<Map<String, Object>> properties = result['properties'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> properties = result['properties']! as List<Map<String, Object>>;
       expect(properties, hasLength(7));
       expect(properties.every((Map<String, Object> property) => property['foo'] == true), isTrue);
 
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(3));
       expect(children.every((Map<String, Object> child) => child['foo'] == true), isTrue);
     });
@@ -135,7 +135,7 @@ void main() {
             return nodes.whereType<StringProperty>().toList();
           },
       ));
-      final List<Map<String, Object>> properties = result['properties'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> properties = result['properties']! as List<Map<String, Object>>;
       expect(properties, hasLength(3));
       expect(properties.every((Map<String, Object> property) => property['type'] == 'StringProperty'), isTrue);
     });
@@ -154,7 +154,7 @@ void main() {
             ];
           },
       ));
-      final List<Map<String, Object>> properties = result['properties'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> properties = result['properties']! as List<Map<String, Object>>;
       expect(properties, hasLength(1));
       expect(properties.single['name'], 'foo');
     });
@@ -166,7 +166,7 @@ void main() {
             return nodes.where((DiagnosticsNode node) => node.getProperties().isEmpty).toList();
           },
       ));
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(1));
     });
 
@@ -177,7 +177,7 @@ void main() {
             return nodes.expand((DiagnosticsNode node) => node.getChildren()).toList();
           },
       ));
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(3));
       expect(children.first['name'], 'child node B1');
     });
@@ -190,11 +190,11 @@ void main() {
             return nodes.take(2).toList();
           },
       ));
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(3));
       expect(children.last['truncated'], isTrue);
 
-      final List<Map<String, Object>> properties = result['properties'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> properties = result['properties']! as List<Map<String, Object>>;
       expect(properties, hasLength(3));
       expect(properties.last['truncated'], isTrue);
     });
@@ -207,11 +207,11 @@ void main() {
             return delegate.copyWith(includeProperties: false);
           },
       ));
-      final List<Map<String, Object>> properties = result['properties'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> properties = result['properties']! as List<Map<String, Object>>;
       expect(properties, hasLength(7));
       expect(properties.every((Map<String, Object> property) => !property.containsKey('properties')), isTrue);
 
-      final List<Map<String, Object>> children = result['children'] as List<Map<String, Object>>;
+      final List<Map<String, Object>> children = result['children']! as List<Map<String, Object>>;
       expect(children, hasLength(3));
       expect(children.every((Map<String, Object> child) => !child.containsKey('properties')), isTrue);
     });

packages/flutter/test/foundation/diagnostics_test.dart

@@ -137,7 +137,7 @@ void validateIterableFlagsPropertyJsonSerialization(FlagsSummary<Object?> proper
 void validateIterablePropertyJsonSerialization(IterableProperty<Object> property) {
   final Map<String, Object> json = simulateJsonSerialization(property);
   if (property.value != null) {
-    final List<Object> valuesJson = json['values'] as List<Object>;
+    final List<Object> valuesJson = json['values']! as List<Object>;
     final List<String> expectedValues = property.value!.map<String>((Object value) => value.toString()).toList();
     expect(listEquals(valuesJson, expectedValues), isTrue);
   } else {

packages/flutter/test/material/circle_avatar_test.dart

@@ -25,7 +25,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(backgroundColor));
 
@@ -47,7 +47,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(backgroundColor));
 
@@ -67,7 +67,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.image!.fit, equals(BoxFit.cover));
   });
@@ -87,7 +87,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(40.0, 40.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(fallback.primaryColorDark));
 
@@ -112,7 +112,7 @@ void main() {
     );
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(theme.primaryColorLight));
 
@@ -137,7 +137,7 @@ void main() {
     );
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(theme.primaryColorDark));
 
@@ -204,7 +204,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(backgroundColor));
 
@@ -226,7 +226,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(backgroundColor));
 
@@ -249,7 +249,7 @@ void main() {
 
     final RenderConstrainedBox box = tester.renderObject(find.byType(CircleAvatar));
     expect(box.size, equals(const Size(100.0, 100.0)));
-    final RenderDecoratedBox child = box.child as RenderDecoratedBox;
+    final RenderDecoratedBox child = box.child! as RenderDecoratedBox;
     final BoxDecoration decoration = child.decoration as BoxDecoration;
     expect(decoration.color, equals(backgroundColor));
 

packages/flutter/test/material/data_table_test.dart

@@ -956,7 +956,7 @@ void main() {
 
     Table table = tester.widget(find.byType(Table));
     TableRow tableRow = table.children.last;
-    BoxDecoration boxDecoration = tableRow.decoration as BoxDecoration;
+    BoxDecoration boxDecoration = tableRow.decoration! as BoxDecoration;
     expect(boxDecoration.border!.top.width, 1.0);
 
     const double thickness =  4.2;
@@ -973,7 +973,7 @@ void main() {
     );
     table = tester.widget(find.byType(Table));
     tableRow = table.children.last;
-    boxDecoration = tableRow.decoration as BoxDecoration;
+    boxDecoration = tableRow.decoration! as BoxDecoration;
     expect(boxDecoration.border!.top.width, thickness);
   });
 
@@ -1007,7 +1007,7 @@ void main() {
 
     Table table = tester.widget(find.byType(Table));
     TableRow tableRow = table.children.last;
-    BoxDecoration boxDecoration = tableRow.decoration as BoxDecoration;
+    BoxDecoration boxDecoration = tableRow.decoration! as BoxDecoration;
     expect(boxDecoration.border!.bottom.width, 1.0);
 
     await tester.pumpWidget(
@@ -1022,7 +1022,7 @@ void main() {
     );
     table = tester.widget(find.byType(Table));
     tableRow = table.children.last;
-    boxDecoration = tableRow.decoration as BoxDecoration;
+    boxDecoration = tableRow.decoration! as BoxDecoration;
     expect(boxDecoration.border!.bottom.width, 0.0);
   });
 
@@ -1175,7 +1175,7 @@ void main() {
     BoxDecoration lastTableRowBoxDecoration() {
       final Table table = tester.widget(find.byType(Table));
       final TableRow tableRow = table.children.last;
-      return tableRow.decoration as BoxDecoration;
+      return tableRow.decoration! as BoxDecoration;
     }
 
     await tester.pumpWidget(MaterialApp(
@@ -1229,7 +1229,7 @@ void main() {
     BoxDecoration lastTableRowBoxDecoration() {
       final Table table = tester.widget(find.byType(Table));
       final TableRow tableRow = table.children.last;
-      return tableRow.decoration as BoxDecoration;
+      return tableRow.decoration! as BoxDecoration;
     }
 
     await tester.pumpWidget(MaterialApp(
@@ -1276,7 +1276,7 @@ void main() {
 
     final TestGesture gesture = await tester.startGesture(tester.getCenter(find.text('Content1')));
     await tester.pump(const Duration(milliseconds: 200)); // splash is well underway
-    final RenderBox box = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox box = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     expect(box, paints..circle(x: 68.0, y: 24.0, color: pressedColor));
     await gesture.up();
   });

packages/flutter/test/material/data_table_theme_test.dart

@@ -246,5 +246,5 @@ void main() {
 BoxDecoration _tableRowBoxDecoration({required WidgetTester tester, required int index}) {
   final Table table = tester.widget(find.byType(Table));
   final TableRow tableRow = table.children[index];
-  return tableRow.decoration as BoxDecoration;
+  return tableRow.decoration! as BoxDecoration;
 }

packages/flutter/test/material/outlined_button_test.dart

@@ -635,7 +635,7 @@ void main() {
     BorderSide getBorderSide() {
       final OutlinedBorder border = tester.widget<Material>(
         find.descendant(of: outlinedButton, matching: find.byType(Material))
-      ).shape as OutlinedBorder;
+      ).shape! as OutlinedBorder;
       return border.side;
     }
 
@@ -1180,11 +1180,11 @@ PhysicalModelLayer _findPhysicalLayer(Element element) {
   expect(element, isNotNull);
   RenderObject? object = element.renderObject;
   while (object != null && object is! RenderRepaintBoundary && object is! RenderView) {
-    object = object.parent as RenderObject;
+    object = object.parent as RenderObject?;
   }
   expect(object!.debugLayer, isNotNull);
   expect(object.debugLayer!.firstChild, isA<PhysicalModelLayer>());
-  final PhysicalModelLayer layer = object.debugLayer!.firstChild as PhysicalModelLayer;
+  final PhysicalModelLayer layer = object.debugLayer!.firstChild! as PhysicalModelLayer;
   final Layer child = layer.firstChild!;
   return child is PhysicalModelLayer ? child : layer;
 }

packages/flutter/test/material/raw_material_button_test.dart

@@ -32,7 +32,7 @@ void main() {
     await tester.tap(find.text('BUTTON'));
     await tester.pump(const Duration(milliseconds: 10));
 
-    final RenderBox splash = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox splash = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     expect(splash, paints..circle(color: splashColor));
 
     await tester.pumpAndSettle();
@@ -72,7 +72,7 @@ void main() {
     await tester.pump(const Duration(milliseconds: 10));
 
     if (!kIsWeb) {
-      final RenderBox splash = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+      final RenderBox splash = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
       expect(splash, paints..circle(color: splashColor));
     }
 
@@ -90,7 +90,7 @@ void main() {
     await tester.sendKeyEvent(LogicalKeyboardKey.space);
     await tester.pump(const Duration(milliseconds: 10));
 
-    final RenderBox splash = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox splash = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     expect(splash, paints..circle(color: splashColor));
 
     await tester.pumpAndSettle();
@@ -195,7 +195,7 @@ void main() {
     await tester.pump(); // start gesture
     await tester.pump(const Duration(milliseconds: 200)); // wait for splash to be well under way
 
-    final RenderBox box = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox box = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     // centered in material button.
     expect(box, paints..circle(x: 44.0, y: 18.0, color: splashColor));
     await gesture.up();
@@ -226,7 +226,7 @@ void main() {
     final TestGesture gesture = await tester.startGesture(top);
     await tester.pump(); // start gesture
     await tester.pump(const Duration(milliseconds: 200)); // wait for splash to be well under way
-    final RenderBox box = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox box = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     // paints above above material
     expect(box, paints..circle(x: 44.0, y: 0.0, color: splashColor));
     await gesture.up();
@@ -325,7 +325,7 @@ void main() {
         ),
       ),
     );
-    final RenderBox box = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox box = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     expect(box, isNot(paints..rect(color: focusColor)));
 
     focusNode.requestFocus();
@@ -424,7 +424,7 @@ void main() {
         ),
       ),
     );
-    final RenderBox box = Material.of(tester.element(find.byType(InkWell))) as RenderBox;
+    final RenderBox box = Material.of(tester.element(find.byType(InkWell)))! as RenderBox;
     final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
     await gesture.addPointer();
     addTearDown(gesture.removePointer);

packages/flutter/test/painting/colors_test.dart

@@ -429,7 +429,7 @@ void main() {
 
   test('ColorDiagnosticsProperty includes valueProperties in JSON', () {
     ColorProperty property = ColorProperty('foo', const Color.fromARGB(10, 20, 30, 40));
-    final Map<String, Object> valueProperties = property.toJsonMap(const DiagnosticsSerializationDelegate())['valueProperties'] as Map<String, Object>;
+    final Map<String, Object> valueProperties = property.toJsonMap(const DiagnosticsSerializationDelegate())['valueProperties']! as Map<String, Object>;
     expect(valueProperties['alpha'], 10);
     expect(valueProperties['red'], 20);
     expect(valueProperties['green'], 30);

packages/flutter/test/painting/decoration_test.dart

@@ -134,13 +134,13 @@ void main() {
     const BoxDecoration a = BoxDecoration(color: Color(0xFFFFFFFF));
     const BoxDecoration b = BoxDecoration(color: Color(0x00000000));
 
-    BoxDecoration c = Decoration.lerp(a, b, 0.0) as BoxDecoration;
+    BoxDecoration c = Decoration.lerp(a, b, 0.0)! as BoxDecoration;
     expect(c.color, equals(a.color));
 
-    c = Decoration.lerp(a, b, 0.25) as BoxDecoration;
+    c = Decoration.lerp(a, b, 0.25)! as BoxDecoration;
     expect(c.color, equals(Color.lerp(const Color(0xFFFFFFFF), const Color(0x00000000), 0.25)));
 
-    c = Decoration.lerp(a, b, 1.0) as BoxDecoration;
+    c = Decoration.lerp(a, b, 1.0)! as BoxDecoration;
     expect(c.color, equals(b.color));
   });
 

packages/flutter/test/painting/image_cache_test.dart

@@ -161,10 +161,10 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
     final TestImageStreamCompleter resultingCompleter2 = imageCache!.putIfAbsent(testImage, () {
       return completer2;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(resultingCompleter1, completer1);
     expect(resultingCompleter2, completer1);
@@ -178,7 +178,7 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(imageCache!.statusForKey(testImage).pending, true);
     expect(imageCache!.statusForKey(testImage).live, true);
@@ -191,7 +191,7 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter2 = imageCache!.putIfAbsent(testImage, () {
       return completer2;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(resultingCompleter1, completer1);
     expect(resultingCompleter2, completer2);
@@ -205,13 +205,13 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     imageCache!.evict(testImage);
 
     final TestImageStreamCompleter resultingCompleter2 = imageCache!.putIfAbsent(testImage, () {
       return completer2;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(resultingCompleter1, completer1);
     expect(resultingCompleter2, completer2);
@@ -242,7 +242,7 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(resultingCompleter1, completer1);
     expect(imageCache!.containsKey(testImage), true);
@@ -255,7 +255,7 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     // Mark as complete
     completer1.testSetImage(testImage);
@@ -276,7 +276,7 @@ void main() {
 
     final TestImageStreamCompleter resultingCompleter1 = imageCache!.putIfAbsent(testImage, () {
       return completer1;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
     expect(imageCache!.statusForKey(testImage).pending, false);
     expect(imageCache!.statusForKey(testImage).keepAlive, true);
@@ -284,7 +284,7 @@ void main() {
     expect(imageCache!.statusForKey(testImage2).untracked, true);
     final TestImageStreamCompleter resultingCompleter2 = imageCache!.putIfAbsent(testImage2, () {
       return completer2;
-    }) as TestImageStreamCompleter;
+    })! as TestImageStreamCompleter;
 
 
     expect(imageCache!.statusForKey(testImage).pending, false);

packages/flutter/test/painting/text_painter_rtl_test.dart

@@ -43,7 +43,7 @@ void main() {
            //      0       12345678      9      101234567       18     90123456       27
       style: TextStyle(fontFamily: 'Ahem', fontSize: 10.0),
     );
-    TextSpan textSpan = painter.text as TextSpan;
+    TextSpan textSpan = painter.text! as TextSpan;
     expect(textSpan.text!.length, 28);
     painter.layout();
 
@@ -127,7 +127,7 @@ void main() {
       // The list is currently in the wrong order (so selection boxes will paint in the wrong order).
     );
 
-    textSpan = painter.text as TextSpan;
+    textSpan = painter.text! as TextSpan;
     final List<List<TextBox>> list = <List<TextBox>>[
       for (int index = 0; index < textSpan.text!.length; index += 1)
         painter.getBoxesForSelection(TextSelection(baseOffset: index, extentOffset: index + 1)),
@@ -175,7 +175,7 @@ void main() {
            //      0       12345678      9      101234567       18     90123456       27
       style: TextStyle(fontFamily: 'Ahem', fontSize: 10.0),
     );
-    final TextSpan textSpan = painter.text as TextSpan;
+    final TextSpan textSpan = painter.text! as TextSpan;
     expect(textSpan.text!.length, 28);
     painter.layout();
 
@@ -265,7 +265,7 @@ void main() {
       text: 'A\u05D0', // A, Alef
       style: TextStyle(fontFamily: 'Ahem', fontSize: 10.0),
     );
-    final TextSpan textSpan = painter.text as TextSpan;
+    final TextSpan textSpan = painter.text! as TextSpan;
     expect(textSpan.text!.length, 2);
     painter.layout(maxWidth: 10.0);
 

packages/flutter/test/rendering/baseline_test.dart

@@ -20,7 +20,7 @@ void main() {
         child: child = RenderSizedBox(const Size(100.0, 100.0)),
       ),
     );
-    final BoxParentData childParentData = child.parentData as BoxParentData;
+    final BoxParentData childParentData = child.parentData! as BoxParentData;
 
     layout(root, phase: EnginePhase.layout);
     expect(childParentData.offset.dx, equals(0.0));

packages/flutter/test/rendering/box_test.dart

@@ -308,7 +308,7 @@ void main() {
       padding: const EdgeInsets.all(10.0),
     );
     layout(paddedBox);
-    final BoxParentData parentData = coloredBox.parentData as BoxParentData;
+    final BoxParentData parentData = coloredBox.parentData! as BoxParentData;
     expect(parentData.offset.dx, isNot(equals(0.0)));
     paddedBox.child = null;
 
@@ -535,7 +535,7 @@ void main() {
       ),
       alignment: Alignment.center,
     );
-    final FlexParentData flexParentData = flexible.parentData as FlexParentData;
+    final FlexParentData flexParentData = flexible.parentData! as FlexParentData;
     flexParentData.flex = 1;
     flexParentData.fit = FlexFit.tight;
 
@@ -559,7 +559,7 @@ void main() {
       ),
       alignment: Alignment.center,
     );
-    final FlexParentData flexParentData = flexible.parentData as FlexParentData;
+    final FlexParentData flexParentData = flexible.parentData! as FlexParentData;
     flexParentData.flex = 1;
     flexParentData.fit = FlexFit.tight;
 

packages/flutter/test/rendering/flex_test.dart

@@ -82,7 +82,7 @@ void main() {
         flexible,
       ],
     );
-    final FlexParentData flexParentData = flexible.parentData as FlexParentData;
+    final FlexParentData flexParentData = flexible.parentData! as FlexParentData;
     flexParentData.flex = 1;
     const BoxConstraints viewport = BoxConstraints(maxHeight: 100.0, maxWidth: 100.0);
     layout(flex, constraints: viewport);
@@ -105,7 +105,7 @@ void main() {
         flexible,
       ],
     );
-    final FlexParentData flexParentData = flexible.parentData as FlexParentData;
+    final FlexParentData flexParentData = flexible.parentData! as FlexParentData;
     flexParentData.flex = 1;
     const BoxConstraints viewport = BoxConstraints(maxHeight: 100.0, maxWidth: 100.0);
     layout(flex, constraints: viewport);
@@ -165,7 +165,7 @@ void main() {
     expect(box2.size.width, equals(0.0));
     expect(box2.size.height, equals(0.0));
 
-    final FlexParentData box2ParentData = box2.parentData as FlexParentData;
+    final FlexParentData box2ParentData = box2.parentData! as FlexParentData;
     box2ParentData.flex = 1;
     flex.markNeedsLayout();
     pumpFrame();
@@ -180,7 +180,7 @@ void main() {
     final RenderDecoratedBox box2 = RenderDecoratedBox(decoration: const BoxDecoration());
     final RenderFlex flex = RenderFlex(textDirection: TextDirection.ltr);
     flex.setupParentData(box2);
-    final FlexParentData box2ParentData = box2.parentData as FlexParentData;
+    final FlexParentData box2ParentData = box2.parentData! as FlexParentData;
     box2ParentData.flex = 2;
     flex.addAll(<RenderBox>[box1, box2]);
     layout(flex, constraints: const BoxConstraints(
@@ -216,7 +216,7 @@ void main() {
       minWidth: 0.0, maxWidth: 500.0, minHeight: 0.0, maxHeight: 400.0),
     );
     Offset getOffset(RenderBox box) {
-      final FlexParentData parentData = box.parentData as FlexParentData;
+      final FlexParentData parentData = box.parentData! as FlexParentData;
       return parentData.offset;
     }
     expect(getOffset(box1).dx, equals(50.0));
@@ -246,7 +246,7 @@ void main() {
       minWidth: 0.0, maxWidth: 500.0, minHeight: 0.0, maxHeight: 400.0),
     );
     Offset getOffset(RenderBox box) {
-      final FlexParentData parentData = box.parentData as FlexParentData;
+      final FlexParentData parentData = box.parentData! as FlexParentData;
       return parentData.offset;
     }
     expect(getOffset(box1).dx, equals(0.0));
@@ -257,7 +257,7 @@ void main() {
     expect(box3.size.width, equals(100.0));
 
     void setFit(RenderBox box, FlexFit fit) {
-      final FlexParentData parentData = box.parentData as FlexParentData;
+      final FlexParentData parentData = box.parentData! as FlexParentData;
       parentData.flex = 1;
       parentData.fit = fit;
     }
@@ -298,7 +298,7 @@ void main() {
       minWidth: 0.0, maxWidth: 500.0, minHeight: 0.0, maxHeight: 400.0),
     );
     Offset getOffset(RenderBox box) {
-      final FlexParentData parentData = box.parentData as FlexParentData;
+      final FlexParentData parentData = box.parentData! as FlexParentData;
       return parentData.offset;
     }
     expect(getOffset(box1).dx, equals(0.0));
@@ -310,7 +310,7 @@ void main() {
     expect(flex.size.width, equals(300.0));
 
     void setFit(RenderBox box, FlexFit fit) {
-      final FlexParentData parentData = box.parentData as FlexParentData;
+      final FlexParentData parentData = box.parentData! as FlexParentData;
       parentData.flex = 1;
       parentData.fit = fit;
     }
@@ -360,7 +360,7 @@ void main() {
     flex.addAll(<RenderBox>[box1, box2, box3]);
     layout(parent);
     expect(flex.size, const Size(300.0, 100.0));
-    final FlexParentData box2ParentData = box2.parentData as FlexParentData;
+    final FlexParentData box2ParentData = box2.parentData! as FlexParentData;
     box2ParentData.flex = 1;
     box2ParentData.fit = FlexFit.loose;
     flex.markNeedsLayout();
@@ -399,7 +399,7 @@ void main() {
       child: flex,
     );
     flex.addAll(<RenderBox>[box1, box2, box3]);
-    final FlexParentData box2ParentData = box2.parentData as FlexParentData;
+    final FlexParentData box2ParentData = box2.parentData! as FlexParentData;
     box2ParentData.flex = 1;
     final List<dynamic> exceptions = <dynamic>[];
     layout(parent, onErrors: () {
@@ -426,7 +426,7 @@ void main() {
       child: flex,
     );
     flex.addAll(<RenderBox>[box1, box2, box3]);
-    final FlexParentData box2ParentData = box2.parentData as FlexParentData;
+    final FlexParentData box2ParentData = box2.parentData! as FlexParentData;
     box2ParentData.flex = 1;
     box2ParentData.fit = FlexFit.loose;
     final List<dynamic> exceptions = <dynamic>[];

packages/flutter/test/rendering/non_render_object_root_test.dart

@@ -34,7 +34,7 @@ class RealRoot extends AbstractNode {
   }
 
   @override
-  PipelineOwner get owner => super.owner as PipelineOwner;
+  PipelineOwner? get owner => super.owner as PipelineOwner?;
 
   void layout() {
     child.layout(BoxConstraints.tight(const Size(500.0, 500.0)));

packages/flutter/test/rendering/object_test.dart

@@ -102,37 +102,37 @@ void main() {
 
   test('PaintingContext.pushClipRect reuses the layer', () {
     _testPaintingContextLayerReuse<ClipRectLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushClipRect(true, offset, Rect.zero, painter, oldLayer: oldLayer as ClipRectLayer);
+      return context.pushClipRect(true, offset, Rect.zero, painter, oldLayer: oldLayer as ClipRectLayer?);
     });
   });
 
   test('PaintingContext.pushClipRRect reuses the layer', () {
     _testPaintingContextLayerReuse<ClipRRectLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushClipRRect(true, offset, Rect.zero, RRect.fromRectAndRadius(Rect.zero, const Radius.circular(1.0)), painter, oldLayer: oldLayer as ClipRRectLayer);
+      return context.pushClipRRect(true, offset, Rect.zero, RRect.fromRectAndRadius(Rect.zero, const Radius.circular(1.0)), painter, oldLayer: oldLayer as ClipRRectLayer?);
     });
   });
 
   test('PaintingContext.pushClipPath reuses the layer', () {
     _testPaintingContextLayerReuse<ClipPathLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushClipPath(true, offset, Rect.zero, Path(), painter, oldLayer: oldLayer as ClipPathLayer);
+      return context.pushClipPath(true, offset, Rect.zero, Path(), painter, oldLayer: oldLayer as ClipPathLayer?);
     });
   });
 
   test('PaintingContext.pushColorFilter reuses the layer', () {
     _testPaintingContextLayerReuse<ColorFilterLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushColorFilter(offset, const ColorFilter.mode(Color.fromRGBO(0, 0, 0, 1.0), BlendMode.clear), painter, oldLayer: oldLayer as ColorFilterLayer);
+      return context.pushColorFilter(offset, const ColorFilter.mode(Color.fromRGBO(0, 0, 0, 1.0), BlendMode.clear), painter, oldLayer: oldLayer as ColorFilterLayer?);
     });
   });
 
   test('PaintingContext.pushTransform reuses the layer', () {
     _testPaintingContextLayerReuse<TransformLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushTransform(true, offset, Matrix4.identity(), painter, oldLayer: oldLayer as TransformLayer);
+      return context.pushTransform(true, offset, Matrix4.identity(), painter, oldLayer: oldLayer as TransformLayer?);
     });
   });
 
   test('PaintingContext.pushOpacity reuses the layer', () {
     _testPaintingContextLayerReuse<OpacityLayer>((PaintingContextCallback painter, PaintingContext context, Offset offset, Layer? oldLayer) {
-      return context.pushOpacity(offset, 100, painter, oldLayer: oldLayer as OpacityLayer);
+      return context.pushOpacity(offset, 100, painter, oldLayer: oldLayer as OpacityLayer?);
     });
   });
 }

packages/flutter/test/rendering/proxy_box_test.dart

@@ -230,7 +230,7 @@ void main() {
     expect(getPixel(0, 0), equals(0x00000080));
     expect(getPixel(image.width - 1, 0 ), equals(0xffffffff));
 
-    final OffsetLayer layer = boundary.debugLayer as OffsetLayer;
+    final OffsetLayer layer = boundary.debugLayer! as OffsetLayer;
 
     image = await layer.toImage(Offset.zero & const Size(20.0, 20.0));
     expect(image.width, equals(20));

packages/flutter/test/rendering/sliver_cache_test.dart

@@ -912,7 +912,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
   RenderSliverList createRenderSliverList() {
     assert(_renderObject == null);
     _renderObject = RenderSliverList(childManager: this);
-    return _renderObject as RenderSliverList;
+    return _renderObject! as RenderSliverList;
   }
 
   RenderSliverFixedExtentList createRenderSliverFixedExtentList() {
@@ -921,7 +921,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
       childManager: this,
       itemExtent: 100.0,
     );
-    return _renderObject as RenderSliverFixedExtentList;
+    return _renderObject! as RenderSliverFixedExtentList;
   }
 
   RenderSliverGrid createRenderSliverGrid() {
@@ -933,7 +933,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
         childAspectRatio: 4.0,
       ),
     );
-    return _renderObject as RenderSliverGrid;
+    return _renderObject! as RenderSliverGrid;
   }
 
   int? _currentlyUpdatingChildIndex;
@@ -973,7 +973,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
   @override
   void didAdoptChild(RenderBox child) {
     assert(_currentlyUpdatingChildIndex != null);
-    final SliverMultiBoxAdaptorParentData childParentData = child.parentData as SliverMultiBoxAdaptorParentData;
+    final SliverMultiBoxAdaptorParentData childParentData = child.parentData! as SliverMultiBoxAdaptorParentData;
     childParentData.index = _currentlyUpdatingChildIndex;
   }
 

packages/flutter/test/rendering/sliver_fixed_extent_layout_test.dart

@@ -56,7 +56,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
     _renderObject = RenderSliverFillViewport(
       childManager: this,
     );
-    return _renderObject as RenderSliverFillViewport;
+    return _renderObject! as RenderSliverFillViewport;
   }
 
   int? _currentlyUpdatingChildIndex;
@@ -96,7 +96,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
   @override
   void didAdoptChild(RenderBox child) {
     assert(_currentlyUpdatingChildIndex != null);
-    final SliverMultiBoxAdaptorParentData childParentData = child.parentData as SliverMultiBoxAdaptorParentData;
+    final SliverMultiBoxAdaptorParentData childParentData = child.parentData! as SliverMultiBoxAdaptorParentData;
     childParentData.index = _currentlyUpdatingChildIndex;
   }
 

packages/flutter/test/rendering/slivers_block_test.dart

@@ -59,7 +59,7 @@ class TestRenderSliverBoxChildManager extends RenderSliverBoxChildManager {
   @override
   void didAdoptChild(RenderBox child) {
     assert(_currentlyUpdatingChildIndex != null);
-    final SliverMultiBoxAdaptorParentData childParentData = child.parentData as SliverMultiBoxAdaptorParentData;
+    final SliverMultiBoxAdaptorParentData childParentData = child.parentData! as SliverMultiBoxAdaptorParentData;
     childParentData.index = _currentlyUpdatingChildIndex;
   }
 
@@ -288,7 +288,7 @@ void main() {
     );
     layout(root);
 
-    final SliverMultiBoxAdaptorParentData parentData = a.parentData as SliverMultiBoxAdaptorParentData;
+    final SliverMultiBoxAdaptorParentData parentData = a.parentData! as SliverMultiBoxAdaptorParentData;
     parentData.layoutOffset = 0.001;
 
     root.offset = ViewportOffset.fixed(900.0);
@@ -323,7 +323,7 @@ void main() {
     );
     layout(root);
 
-    final SliverMultiBoxAdaptorParentData parentData = a.parentData as SliverMultiBoxAdaptorParentData;
+    final SliverMultiBoxAdaptorParentData parentData = a.parentData! as SliverMultiBoxAdaptorParentData;
     // Simulate double precision error.
     parentData.layoutOffset = -0.0000000000001;
 

packages/flutter/test/rendering/slivers_test.dart

@@ -288,11 +288,11 @@ void main() {
     expect(root.size.width, equals(800.0));
     expect(root.size.height, equals(600.0));
 
-    final RenderSliver sliverA = a.parent as RenderSliver;
+    final RenderSliver sliverA = a.parent! as RenderSliver;
-    final RenderSliver sliverB = b.parent as RenderSliver;
+    final RenderSliver sliverB = b.parent! as RenderSliver;
-    final RenderSliver sliverC = c.parent as RenderSliver;
+    final RenderSliver sliverC = c.parent! as RenderSliver;
-    final RenderSliver sliverD = d.parent as RenderSliver;
+    final RenderSliver sliverD = d.parent! as RenderSliver;
-    final RenderSliver sliverE = e.parent as RenderSliver;
+    final RenderSliver sliverE = e.parent! as RenderSliver;
 
     expect(a.localToGlobal(const Offset(0.0, 0.0)), const Offset(0.0, 0.0));
     expect(b.localToGlobal(const Offset(0.0, 0.0)), const Offset(400.0, 0.0));

packages/flutter/test/rendering/stack_test.dart

@@ -30,7 +30,7 @@ void main() {
       textDirection: TextDirection.ltr,
       children: <RenderBox>[red, green],
     );
-    final StackParentData greenParentData = green.parentData as StackParentData;
+    final StackParentData greenParentData = green.parentData! as StackParentData;
     greenParentData
       ..top = 0.0
       ..right = 0.0
@@ -79,7 +79,7 @@ void main() {
           clipBehavior: clip,
       );
       { // Make sure that the child is positioned so the stack will consider it as overflowed.
-        final StackParentData parentData = child.parentData as StackParentData;
+        final StackParentData parentData = child.parentData! as StackParentData;
         parentData.left = parentData.right = 0;
       }
       layout(stack, constraints: viewport, phase: EnginePhase.composite, onErrors: expectOverflowedErrors);

packages/flutter/test/widgets/animated_container_test.dart

@@ -45,7 +45,7 @@ void main() {
       ),
     );
 
-    final RenderDecoratedBox box = key.currentContext!.findRenderObject() as RenderDecoratedBox;
+    final RenderDecoratedBox box = key.currentContext!.findRenderObject()! as RenderDecoratedBox;
     actualDecoration = box.decoration as BoxDecoration;
     expect(actualDecoration.color, equals(decorationA.color));
 

packages/flutter/test/widgets/animated_positioned_test.dart

@@ -42,12 +42,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pumpWidget(
@@ -69,17 +69,17 @@ void main() {
     const Offset first = Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0);
     const Offset last = Offset(37.0 + 59.0 / 2.0, 31.0 + 71.0 / 2.0);
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(first));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(Offset.lerp(first, last, 0.5)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(last));
 
     expect(box, hasAGoodToStringDeep);
@@ -126,12 +126,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pumpWidget(
@@ -155,17 +155,17 @@ void main() {
     const Offset first = Offset(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0);
     const Offset last = Offset(37.0 + 59.0 / 2.0, 31.0 + 71.0 / 2.0);
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(first));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(Offset.lerp(first, last, 0.5)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(last));
 
     expect(box, hasAGoodToStringDeep);
@@ -212,12 +212,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(800.0 - 50.0 - 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(800.0 - 50.0 - 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
 
     await tester.pumpWidget(
@@ -241,17 +241,17 @@ void main() {
     const Offset first = Offset(800.0 - 50.0 - 70.0 / 2.0, 30.0 + 110.0 / 2.0);
     const Offset last = Offset(800.0 - 37.0 - 59.0 / 2.0, 31.0 + 71.0 / 2.0);
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(first));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(Offset.lerp(first, last, 0.5)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(last));
 
     expect(box, hasAGoodToStringDeep);
@@ -296,12 +296,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pumpWidget(
@@ -320,12 +320,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(100.0, 100.0)));
 
     await tester.pumpWidget(
@@ -344,17 +344,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(100.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(150.0, 150.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(200.0, 200.0)));
   });
 
@@ -379,12 +379,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pumpWidget(
@@ -403,17 +403,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 150.0)));
   });
 
@@ -440,12 +440,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pumpWidget(
@@ -466,12 +466,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(100.0, 100.0)));
 
     await tester.pumpWidget(
@@ -492,17 +492,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(100.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(150.0, 150.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(200.0, 200.0)));
   });
 
@@ -529,12 +529,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(50.0, 50.0)));
 
     await tester.pumpWidget(
@@ -555,17 +555,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(350.0, 150.0)));
   });
 
@@ -592,12 +592,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(750.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(750.0, 50.0)));
 
     await tester.pumpWidget(
@@ -618,12 +618,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(750.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(700.0, 100.0)));
 
     await tester.pumpWidget(
@@ -644,17 +644,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(700.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(650.0, 150.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(600.0, 200.0)));
   });
 
@@ -681,12 +681,12 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(750.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(750.0, 50.0)));
 
     await tester.pumpWidget(
@@ -707,17 +707,17 @@ void main() {
       ),
     );
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(450.0, 50.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(450.0, 100.0)));
 
     await tester.pump(const Duration(seconds: 1));
 
-    box = key.currentContext!.findRenderObject() as RenderBox;
+    box = key.currentContext!.findRenderObject()! as RenderBox;
     expect(box.localToGlobal(box.size.center(Offset.zero)), equals(const Offset(450.0, 150.0)));
   });
 

packages/flutter_test/lib/src/_matchers_io.dart

@@ -25,11 +25,10 @@ Future<ui.Image> captureImage(Element element) {
   assert(element.renderObject != null);
   RenderObject renderObject = element.renderObject!;
   while (!renderObject.isRepaintBoundary) {
-    renderObject = renderObject.parent as RenderObject;
+    renderObject = renderObject.parent! as RenderObject;
-    assert(renderObject != null);
   }
   assert(!renderObject.debugNeedsPaint);
-  final OffsetLayer layer = renderObject.debugLayer as OffsetLayer;
+  final OffsetLayer layer = renderObject.debugLayer! as OffsetLayer;
   return layer.toImage(renderObject.paintBounds);
 }
 

packages/flutter_test/lib/src/_matchers_web.dart

@@ -83,8 +83,7 @@ RenderObject _findRepaintBoundary(Element element) {
   assert(element.renderObject != null);
   RenderObject renderObject = element.renderObject!;
   while (!renderObject.isRepaintBoundary) {
-    renderObject = renderObject.parent as RenderObject;
+    renderObject = renderObject.parent! as RenderObject;
-    assert(renderObject != null);
   }
   return renderObject;
 }

packages/flutter_test/lib/src/accessibility.dart

@@ -198,7 +198,7 @@ class MinimumTextContrastGuideline extends AccessibilityGuideline {
   Future<Evaluation> evaluate(WidgetTester tester) async {
     final SemanticsNode root = tester.binding.pipelineOwner.semanticsOwner!.rootSemanticsNode!;
     final RenderView renderView = tester.binding.renderView;
-    final OffsetLayer layer = renderView.debugLayer as OffsetLayer;
+    final OffsetLayer layer = renderView.debugLayer! as OffsetLayer;
     ui.Image? image;
     final ByteData byteData = (await tester.binding.runAsync<ByteData?>(() async {
       // Needs to be the same pixel ratio otherwise our dimensions won't match the
@@ -370,7 +370,7 @@ class CustomMinimumContrastGuideline extends AccessibilityGuideline {
     // Obtain rendered image.
 
     final RenderView renderView = tester.binding.renderView;
-    final OffsetLayer layer = renderView.debugLayer as OffsetLayer;
+    final OffsetLayer layer = renderView.debugLayer! as OffsetLayer;
     ui.Image? image;
     final ByteData byteData = (await tester.binding.runAsync<ByteData?>(() async {
       // Needs to be the same pixel ratio otherwise our dimensions won't match the
@@ -383,7 +383,7 @@ class CustomMinimumContrastGuideline extends AccessibilityGuideline {
     // How to evaluate a single element.
 
     Evaluation evaluateElement(Element element) {
-      final RenderBox renderObject = element.renderObject as RenderBox;
+      final RenderBox renderObject = element.renderObject! as RenderBox;
 
       final Rect originalPaintBounds = renderObject.paintBounds;
 

packages/flutter_test/lib/src/controller.dart

@@ -205,7 +205,7 @@ abstract class WidgetController {
   /// * Use [renderObjectList] if you expect to match several render objects and want all of them.
   T renderObject<T extends RenderObject>(Finder finder) {
     TestAsyncUtils.guardSync();
-    return finder.evaluate().single.renderObject as T;
+    return finder.evaluate().single.renderObject! as T;
   }
 
   /// The render object of the first matching widget according to a
@@ -216,7 +216,7 @@ abstract class WidgetController {
   /// * Use [renderObject] if you only expect to match one render object.
   T firstRenderObject<T extends RenderObject>(Finder finder) {
     TestAsyncUtils.guardSync();
-    return finder.evaluate().first.renderObject as T;
+    return finder.evaluate().first.renderObject! as T;
   }
 
   /// The render objects of the matching widgets in the widget tree.
@@ -226,7 +226,7 @@ abstract class WidgetController {
   Iterable<T> renderObjectList<T extends RenderObject>(Finder finder) {
     TestAsyncUtils.guardSync();
     return finder.evaluate().map<T>((Element element) {
-      final T result = element.renderObject as T;
+      final T result = element.renderObject! as T;
       return result;
     });
   }
@@ -812,8 +812,7 @@ abstract class WidgetController {
   Offset _getElementPoint(Finder finder, Offset sizeToPoint(Size size)) {
     TestAsyncUtils.guardSync();
     final Element element = finder.evaluate().single;
-    final RenderBox box = element.renderObject as RenderBox;
+    final RenderBox box = element.renderObject! as RenderBox;
-    assert(box != null);
     return box.localToGlobal(sizeToPoint(box.size));
   }
 
@@ -822,8 +821,7 @@ abstract class WidgetController {
   Size getSize(Finder finder) {
     TestAsyncUtils.guardSync();
     final Element element = finder.evaluate().single;
-    final RenderBox box = element.renderObject as RenderBox;
+    final RenderBox box = element.renderObject! as RenderBox;
-    assert(box != null);
     return box.size;
   }
 

packages/flutter_test/lib/src/finders.dart

@@ -516,8 +516,7 @@ class _HitTestableFinder extends ChainedFinder {
   @override
   Iterable<Element> filter(Iterable<Element> parentCandidates) sync* {
     for (final Element candidate in parentCandidates) {
-      final RenderBox box = candidate.renderObject as RenderBox;
+      final RenderBox box = candidate.renderObject! as RenderBox;
-      assert(box != null);
       final Offset absoluteOffset = box.localToGlobal(alignment.alongSize(box.size));
       final HitTestResult hitResult = HitTestResult();
       WidgetsBinding.instance!.hitTest(hitResult, absoluteOffset);

packages/flutter_test/lib/src/matchers.dart

@@ -1362,7 +1362,7 @@ class _RendersOnPhysicalModel extends _MatchRenderObject<RenderPhysicalShape, Re
   bool renderObjectMatchesM(Map<dynamic, dynamic> matchState, RenderPhysicalShape renderObject) {
     if (renderObject.clipper.runtimeType != ShapeBorderClipper)
       return failWithDescription(matchState, 'clipper was: ${renderObject.clipper}');
-    final ShapeBorderClipper shapeClipper = renderObject.clipper as ShapeBorderClipper;
+    final ShapeBorderClipper shapeClipper = renderObject.clipper! as ShapeBorderClipper;
 
     if (borderRadius != null && !assertRoundedRectangle(shapeClipper, borderRadius!, matchState))
       return false;
@@ -1430,7 +1430,7 @@ class _RendersOnPhysicalShape extends _MatchRenderObject<RenderPhysicalShape, Re
   bool renderObjectMatchesM(Map<dynamic, dynamic> matchState, RenderPhysicalShape renderObject) {
     if (renderObject.clipper.runtimeType != ShapeBorderClipper)
       return failWithDescription(matchState, 'clipper was: ${renderObject.clipper}');
-    final ShapeBorderClipper shapeClipper = renderObject.clipper as ShapeBorderClipper;
+    final ShapeBorderClipper shapeClipper = renderObject.clipper! as ShapeBorderClipper;
 
     if (shapeClipper.shape != shape)
       return failWithDescription(matchState, 'shape was: ${shapeClipper.shape}');
@@ -1469,7 +1469,7 @@ class _ClipsWithBoundingRect extends _MatchRenderObject<RenderClipPath, RenderCl
   bool renderObjectMatchesM(Map<dynamic, dynamic> matchState, RenderClipPath renderObject) {
     if (renderObject.clipper.runtimeType != ShapeBorderClipper)
       return failWithDescription(matchState, 'clipper was: ${renderObject.clipper}');
-    final ShapeBorderClipper shapeClipper = renderObject.clipper as ShapeBorderClipper;
+    final ShapeBorderClipper shapeClipper = renderObject.clipper! as ShapeBorderClipper;
     if (shapeClipper.shape.runtimeType != RoundedRectangleBorder)
       return failWithDescription(matchState, 'shape was: ${shapeClipper.shape}');
     final RoundedRectangleBorder border = shapeClipper.shape as RoundedRectangleBorder;
@@ -1504,7 +1504,7 @@ class _ClipsWithBoundingRRect extends _MatchRenderObject<RenderClipPath, RenderC
   bool renderObjectMatchesM(Map<dynamic, dynamic> matchState, RenderClipPath renderObject) {
     if (renderObject.clipper.runtimeType != ShapeBorderClipper)
       return failWithDescription(matchState, 'clipper was: ${renderObject.clipper}');
-    final ShapeBorderClipper shapeClipper = renderObject.clipper as ShapeBorderClipper;
+    final ShapeBorderClipper shapeClipper = renderObject.clipper! as ShapeBorderClipper;
     if (shapeClipper.shape.runtimeType != RoundedRectangleBorder)
       return failWithDescription(matchState, 'shape was: ${shapeClipper.shape}');
     final RoundedRectangleBorder border = shapeClipper.shape as RoundedRectangleBorder;
@@ -1527,7 +1527,7 @@ class _ClipsWithShapeBorder extends _MatchRenderObject<RenderClipPath, RenderCli
   bool renderObjectMatchesM(Map<dynamic, dynamic> matchState, RenderClipPath renderObject) {
     if (renderObject.clipper.runtimeType != ShapeBorderClipper)
       return failWithDescription(matchState, 'clipper was: ${renderObject.clipper}');
-    final ShapeBorderClipper shapeClipper = renderObject.clipper as ShapeBorderClipper;
+    final ShapeBorderClipper shapeClipper = renderObject.clipper! as ShapeBorderClipper;
     if (shapeClipper.shape != shape)
       return failWithDescription(matchState, 'shape was: ${shapeClipper.shape}');
     return true;

packages/flutter_test/lib/src/widget_tester.dart

@@ -681,7 +681,7 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
       'therefore no restoration data has been collected to restore from. Did you forget to wrap '
       'your widget tree in a RootRestorationScope?',
     );
-    final Widget widget = (binding.renderViewElement as RenderObjectToWidgetElement<RenderObject>).widget.child!;
+    final Widget widget = (binding.renderViewElement! as RenderObjectToWidgetElement<RenderObject>).widget.child!;
     final TestRestorationData restorationData = binding.restorationManager.restorationData;
     runApp(Container(key: UniqueKey()));
     await pump();