Prefer const constructors (#11853)

* upgrade to linter-0.1.35 * re-enable lint prefer_const_constructors * address review comments
2017-08-31 08:55:21 +02:00 · 2017-08-31 08:55:21 +02:00 · bb4f4070f9
commit bb4f4070f9
parent f0bf7b5c8c
25 changed files with 172 additions and 158 deletions
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@ -71,6 +71,7 @@ linter:
    # === style rules ===
    - always_declare_return_types
    - always_put_control_body_on_new_line
+    # - always_put_required_named_parameters_first # we prefer having parameters in the same order as fields https://github.com/flutter/flutter/issues/10219
    - always_require_non_null_named_parameters
    - always_specify_types
    - annotate_overrides
@ -108,9 +109,11 @@ linter:
    - package_prefixed_library_names
    # - parameter_assignments # we do this commonly
    - prefer_adjacent_string_concatenation
+    # - prefer_asserts_in_initializer_lists # not yet tested
    - prefer_collection_literals
    # - prefer_conditional_assignment # not yet tested
-    # - prefer_const_constructors # https://github.com/dart-lang/linter/issues/752
+    - prefer_const_constructors
+    # - prefer_const_constructors_in_immutables # not yet tested
    # - prefer_constructors_over_static_methods # not yet tested
    - prefer_contains
    # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
@ -122,6 +125,7 @@ linter:
    # - prefer_interpolation_to_compose_strings # not yet tested
    - prefer_is_empty
    - prefer_is_not_empty
+    # - prefer_single_quote_strings # not yet tested
    # - public_member_api_docs # this is the only difference from analysis_options_repo.yaml
    # - recursive_getters # https://github.com/dart-lang/linter/issues/452
    - slash_for_doc_comments
--- a/analysis_options_repo.yaml
+++ b/analysis_options_repo.yaml
@ -65,6 +65,7 @@ linter:
    # === style rules ===
    - always_declare_return_types
    - always_put_control_body_on_new_line
+    # - always_put_required_named_parameters_first # we prefer having parameters in the same order as fields https://github.com/flutter/flutter/issues/10219
    - always_require_non_null_named_parameters
    - always_specify_types
    - annotate_overrides
@ -102,9 +103,11 @@ linter:
    - package_prefixed_library_names
    # - parameter_assignments # we do this commonly
    - prefer_adjacent_string_concatenation
+    # - prefer_asserts_in_initializer_lists # not yet tested
    - prefer_collection_literals
    # - prefer_conditional_assignment # not yet tested
-    # - prefer_const_constructors # https://github.com/dart-lang/linter/issues/752
+    - prefer_const_constructors
+    # - prefer_const_constructors_in_immutables # not yet tested
    # - prefer_constructors_over_static_methods # not yet tested
    - prefer_contains
    # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
@ -116,6 +119,7 @@ linter:
    # - prefer_interpolation_to_compose_strings # not yet tested
    - prefer_is_empty
    - prefer_is_not_empty
+    # - prefer_single_quote_strings # not yet tested
    - public_member_api_docs # this is the only difference from analysis_options_repo.yaml
    # - recursive_getters # https://github.com/dart-lang/linter/issues/452
    - slash_for_doc_comments
--- a/dev/devicelab/bin/tasks/commands_test.dart
+++ b/dev/devicelab/bin/tasks/commands_test.dart
@ -98,7 +98,7 @@ void main() {
      if (result != 0)
        throw 'Received unexpected exit code $result from run process.';
      print('test: validating that the app has in fact closed...');
-      await client.done.timeout(new Duration(seconds: 5));
+      await client.done.timeout(const Duration(seconds: 5));
    });
    return new TaskResult.success(null);
  });
--- a/dev/integration_tests/flavors/lib/main.dart
+++ b/dev/integration_tests/flavors/lib/main.dart
@ -18,7 +18,7 @@ class _FlavorState extends State<Flavor> {
  @override
  void initState() {
    super.initState();
-    new MethodChannel('flavor').invokeMethod('getFlavor').then((String flavor) {
+    const MethodChannel('flavor').invokeMethod('getFlavor').then((String flavor) {
      setState(() {
        _flavor = flavor;
      });
@ -27,8 +27,8 @@ class _FlavorState extends State<Flavor> {

  @override
  Widget build(BuildContext context) {
-    return _flavor == null 
-      ? new Text('Awaiting flavor...')
+    return _flavor == null
+      ? const Text('Awaiting flavor...')
      : new Text(_flavor, key: const ValueKey<String>('flavor'));
  }
 }
--- a/dev/integration_tests/platform_interaction/lib/src/system_navigation.dart
+++ b/dev/integration_tests/platform_interaction/lib/src/system_navigation.dart
@ -16,7 +16,7 @@ Future<TestStepResult> systemNavigatorPop() {

  channel.setMessageHandler((String message) async {
    completer.complete(
-        new TestStepResult('System navigation pop', '', TestStatus.ok));
+        const TestStepResult('System navigation pop', '', TestStatus.ok));
    return '';
  });
  SystemNavigator.pop();
--- a/packages/flutter/lib/src/widgets/widget_inspector.dart
+++ b/packages/flutter/lib/src/widgets/widget_inspector.dart
@ -318,7 +318,7 @@ class _RenderInspectorOverlay extends RenderBox {

  @override
  void performResize() {
-    size = constraints.constrain(new Size(double.INFINITY, double.INFINITY));
+    size = constraints.constrain(const Size(double.INFINITY, double.INFINITY));
  }

  @override
--- a/packages/flutter/test/cupertino/slider_test.dart
+++ b/packages/flutter/test/cupertino/slider_test.dart
@ -181,9 +181,9 @@ void main() {
    ));

    // Disable slider
-    await tester.pumpWidget(new Directionality(
+    await tester.pumpWidget(const Directionality(
      textDirection: TextDirection.ltr,
-      child: new CupertinoSlider(
+      child: const CupertinoSlider(
        value: 0.5,
        onChanged: null,
      ),
--- a/packages/flutter/test/gestures/drag_test.dart
+++ b/packages/flutter/test/gestures/drag_test.dart
@ -253,7 +253,7 @@ void main() {
    tester.route(pointer.move(const Offset(30.0, 25.0), timeStamp: const Duration(milliseconds: 30)));
    tester.route(pointer.move(const Offset(40.0, 25.0), timeStamp: const Duration(milliseconds: 40)));
    tester.route(pointer.move(const Offset(50.0, 25.0), timeStamp: const Duration(milliseconds: 50)));
-    tester.route(new PointerMoveEvent(
+    tester.route(const PointerMoveEvent(
      pointer: 1,
      // Simulate a small synthesized wobble which would have slowed down the
      // horizontal velocity from 1 px/ms and introduced a slight vertical velocity.
--- a/packages/flutter/test/material/button_bar_test.dart
+++ b/packages/flutter/test/material/button_bar_test.dart
@ -8,7 +8,7 @@ import 'package:flutter_test/flutter_test.dart';
 void main() {
  testWidgets('ButtonBar default control smoketest', (WidgetTester tester) async {
    await tester.pumpWidget(
-      new Directionality(
+      const Directionality(
        textDirection: TextDirection.ltr,
        child: const ButtonBar(),
      ),
--- a/packages/flutter/test/material/chip_test.dart
+++ b/packages/flutter/test/material/chip_test.dart
@ -178,13 +178,13 @@ void main() {
  });

  testWidgets('Chip in row works ok', (WidgetTester tester) async {
-    final TextStyle style = new TextStyle(fontFamily: 'Ahem', fontSize: 10.0);
+    final TextStyle style = const TextStyle(fontFamily: 'Ahem', fontSize: 10.0);
    await tester.pumpWidget(
      new MaterialApp(
        home: new Material(
          child: new Row(
            children: <Widget>[
-              new Chip(label: new Text('Test'), labelStyle: style),
+              new Chip(label: const Text('Test'), labelStyle: style),
            ],
          ),
        ),
@ -197,7 +197,7 @@ void main() {
        home: new Material(
          child: new Row(
            children: <Widget>[
-              new Flexible(child: new Chip(label: new Text('Test'), labelStyle: style)),
+              new Flexible(child: new Chip(label: const Text('Test'), labelStyle: style)),
            ],
          ),
        ),
@ -210,7 +210,7 @@ void main() {
        home: new Material(
          child: new Row(
            children: <Widget>[
-              new Expanded(child: new Chip(label: new Text('Test'), labelStyle: style)),
+              new Expanded(child: new Chip(label: const Text('Test'), labelStyle: style)),
            ],
          ),
        ),
@ -228,7 +228,7 @@ void main() {
              child: new Center(
                child: new Chip(
                  onDeleted: () { },
-                  label: new Text('ABC'),
+                  label: const Text('ABC'),
                ),
              ),
            );
--- a/packages/flutter/test/material/page_test.dart
+++ b/packages/flutter/test/material/page_test.dart
@ -276,11 +276,11 @@ void main() {
    final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
      '/': (BuildContext context) => new Material(
        child: new FlatButton(
-          child: new Text('PUSH'),
+          child: const Text('PUSH'),
          onPressed: () { Navigator.of(context).pushNamed('/b'); },
        ),
      ),
-      '/b': (BuildContext context) => new Container(child: new Text('HELLO')),
+      '/b': (BuildContext context) => new Container(child: const Text('HELLO')),
    };
    await tester.pumpWidget(
      new MaterialApp(
--- a/packages/flutter/test/material/popup_menu_test.dart
+++ b/packages/flutter/test/material/popup_menu_test.dart
@ -110,7 +110,7 @@ void main() {
            icon: const Icon(Icons.view_carousel),
            itemBuilder: simplePopupMenuItemBuilder,
        );
-      }, throwsA(new isInstanceOf<AssertionError>()));
+      }, throwsA(const isInstanceOf<AssertionError>()));
    });

    testWidgets('PopupMenuButton creates IconButton when given an icon', (WidgetTester tester) async {
--- a/packages/flutter/test/material/scaffold_test.dart
+++ b/packages/flutter/test/material/scaffold_test.dart
@ -148,11 +148,11 @@ void main() {
    Widget build(TextDirection textDirection) {
      return new Directionality(
        textDirection: textDirection,
-        child: new MediaQuery(
+        child: const MediaQuery(
          data: const MediaQueryData(
            padding: const EdgeInsets.only(bottom: 200.0),
          ),
-          child: new Scaffold(
+          child: const Scaffold(
            floatingActionButton: const FloatingActionButton(
              onPressed: null,
              child: const Text('1'),
--- a/packages/flutter/test/material/slider_test.dart
+++ b/packages/flutter/test/material/slider_test.dart
@ -472,10 +472,10 @@ void main() {
    ));

    // Disable slider
-    await tester.pumpWidget(new Directionality(
+    await tester.pumpWidget(const Directionality(
      textDirection: TextDirection.ltr,
-      child: new Material(
-        child: new Slider(
+      child: const Material(
+        child: const Slider(
          value: 0.5,
          onChanged: null,
        ),
--- a/packages/flutter/test/painting/edge_insets_test.dart
+++ b/packages/flutter/test/painting/edge_insets_test.dart
@ -52,57 +52,58 @@ void main() {
  });

  test('EdgeInsets.resolve()', () {
-    expect(new EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(10.0, 20.0, 30.0, 40.0));
-    expect(new EdgeInsetsDirectional.fromSTEB(99.0, 98.0, 97.0, 96.0).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(97.0, 98.0, 99.0, 96.0));
-    expect(new EdgeInsetsDirectional.only(start: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(963.25, 0.0, 0.0, 0.0));
-    expect(new EdgeInsetsDirectional.only(top: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 963.25, 0.0, 0.0));
-    expect(new EdgeInsetsDirectional.only(end: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 0.0, 963.25, 0.0));
-    expect(new EdgeInsetsDirectional.only(bottom: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 963.25));
-    expect(new EdgeInsetsDirectional.only(start: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 0.0, 963.25, 0.0));
-    expect(new EdgeInsetsDirectional.only(top: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 963.25, 0.0, 0.0));
-    expect(new EdgeInsetsDirectional.only(end: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(963.25, 0.0, 0.0, 0.0));
-    expect(new EdgeInsetsDirectional.only(bottom: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 963.25));
-    expect(new EdgeInsetsDirectional.only(), new EdgeInsetsDirectional.only());
-    expect(new EdgeInsetsDirectional.only(top: 1.0).hashCode, isNot(new EdgeInsetsDirectional.only(bottom: 1.0)));
-    expect(new EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
-           new EdgeInsetsDirectional.fromSTEB(30.0, 20.0, 10.0, 40.0).resolve(TextDirection.rtl));
-    expect(new EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
-     isNot(new EdgeInsetsDirectional.fromSTEB(30.0, 20.0, 10.0, 40.0).resolve(TextDirection.ltr)));
-    expect(new EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
-     isNot(new EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.rtl)));
+    expect(const EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(10.0, 20.0, 30.0, 40.0));
+    expect(const EdgeInsetsDirectional.fromSTEB(99.0, 98.0, 97.0, 96.0).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(97.0, 98.0, 99.0, 96.0));
+    expect(const EdgeInsetsDirectional.only(start: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(963.25, 0.0, 0.0, 0.0));
+    expect(const EdgeInsetsDirectional.only(top: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 963.25, 0.0, 0.0));
+    expect(const EdgeInsetsDirectional.only(end: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 0.0, 963.25, 0.0));
+    expect(const EdgeInsetsDirectional.only(bottom: 963.25).resolve(TextDirection.ltr), const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 963.25));
+    expect(const EdgeInsetsDirectional.only(start: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 0.0, 963.25, 0.0));
+    expect(const EdgeInsetsDirectional.only(top: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 963.25, 0.0, 0.0));
+    expect(const EdgeInsetsDirectional.only(end: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(963.25, 0.0, 0.0, 0.0));
+    expect(const EdgeInsetsDirectional.only(bottom: 963.25).resolve(TextDirection.rtl), const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 963.25));
+    expect(new EdgeInsetsDirectional.only(), new EdgeInsetsDirectional.only()); // ignore: prefer_const_constructors
+    expect(const EdgeInsetsDirectional.only(top: 1.0), isNot(const EdgeInsetsDirectional.only(bottom: 1.0)));
+    expect(const EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
+           const EdgeInsetsDirectional.fromSTEB(30.0, 20.0, 10.0, 40.0).resolve(TextDirection.rtl));
+    expect(const EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
+     isNot(const EdgeInsetsDirectional.fromSTEB(30.0, 20.0, 10.0, 40.0).resolve(TextDirection.ltr)));
+    expect(const EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.ltr),
+     isNot(const EdgeInsetsDirectional.fromSTEB(10.0, 20.0, 30.0, 40.0).resolve(TextDirection.rtl)));
  });

  test('EdgeInsets equality', () {
-    expect(new EdgeInsetsDirectional.only(top: 5.0, bottom: 7.0), new EdgeInsetsDirectional.only(top: 5.0, bottom: 7.0));
-    expect(new EdgeInsets.only(top: 5.0, bottom: 7.0), new EdgeInsetsDirectional.only(top: 5.0, bottom: 7.0));
-    expect(new EdgeInsetsDirectional.only(top: 5.0, bottom: 7.0), new EdgeInsets.only(top: 5.0, bottom: 7.0));
-    expect(new EdgeInsets.only(top: 5.0, bottom: 7.0), new EdgeInsets.only(top: 5.0, bottom: 7.0));
-    expect(new EdgeInsetsDirectional.only(start: 5.0), new EdgeInsetsDirectional.only(start: 5.0));
-    expect(new EdgeInsets.only(left: 5.0), isNot(new EdgeInsetsDirectional.only(start: 5.0)));
-    expect(new EdgeInsetsDirectional.only(start: 5.0), isNot(new EdgeInsets.only(left: 5.0)));
-    expect(new EdgeInsets.only(left: 5.0), new EdgeInsets.only(left: 5.0));
-    expect(new EdgeInsetsDirectional.only(end: 5.0), new EdgeInsetsDirectional.only(end: 5.0));
-    expect(new EdgeInsets.only(right: 5.0), isNot(new EdgeInsetsDirectional.only(end: 5.0)));
-    expect(new EdgeInsetsDirectional.only(end: 5.0), isNot(new EdgeInsets.only(right: 5.0)));
-    expect(new EdgeInsets.only(right: 5.0), new EdgeInsets.only(right: 5.0));
-    expect(new EdgeInsetsDirectional.only(end: 5.0).add(new EdgeInsets.only(right: 5.0)), new EdgeInsetsDirectional.only(end: 5.0).add(new EdgeInsets.only(right: 5.0)));
-    expect(new EdgeInsetsDirectional.only(end: 5.0).add(new EdgeInsets.only(right: 5.0)), isNot(new EdgeInsetsDirectional.only(end: 5.0).add(new EdgeInsets.only(left: 5.0))));
-    expect(new EdgeInsetsDirectional.only(top: 1.0).add(new EdgeInsets.only(top: 2.0)), new EdgeInsetsDirectional.only(top: 3.0).add(new EdgeInsets.only(top: 0.0)));
-    expect(new EdgeInsetsDirectional.only(top: 1.0).add(new EdgeInsets.only(top: 2.0)), new EdgeInsets.only(top: 3.0).add(new EdgeInsetsDirectional.only(top: 0.0)));
-    expect(new EdgeInsetsDirectional.only(top: 1.0).add(new EdgeInsets.only(top: 2.0)), new EdgeInsetsDirectional.only(top: 3.0));
-    expect(new EdgeInsetsDirectional.only(top: 1.0).add(new EdgeInsets.only(top: 2.0)), new EdgeInsets.only(top: 3.0));
+    final double $5 = 5.0; // we want these instances to be separate instances so that we're not just checking with a single object
+    expect(new EdgeInsetsDirectional.only(top: $5, bottom: 7.0), new EdgeInsetsDirectional.only(top: $5, bottom: 7.0));
+    expect(new EdgeInsets.only(top: $5, bottom: 7.0), new EdgeInsetsDirectional.only(top: $5, bottom: 7.0));
+    expect(new EdgeInsetsDirectional.only(top: $5, bottom: 7.0), new EdgeInsets.only(top: $5, bottom: 7.0));
+    expect(new EdgeInsets.only(top: $5, bottom: 7.0), new EdgeInsets.only(top: $5, bottom: 7.0));
+    expect(new EdgeInsetsDirectional.only(start: $5), new EdgeInsetsDirectional.only(start: $5));
+    expect(const EdgeInsets.only(left: 5.0), isNot(const EdgeInsetsDirectional.only(start: 5.0)));
+    expect(const EdgeInsetsDirectional.only(start: 5.0), isNot(const EdgeInsets.only(left: 5.0)));
+    expect(new EdgeInsets.only(left: $5), new EdgeInsets.only(left: $5));
+    expect(new EdgeInsetsDirectional.only(end: $5), new EdgeInsetsDirectional.only(end: $5));
+    expect(const EdgeInsets.only(right: 5.0), isNot(const EdgeInsetsDirectional.only(end: 5.0)));
+    expect(const EdgeInsetsDirectional.only(end: 5.0), isNot(const EdgeInsets.only(right: 5.0)));
+    expect(new EdgeInsets.only(right: $5), new EdgeInsets.only(right: $5));
+    expect(const EdgeInsetsDirectional.only(end: 5.0).add(const EdgeInsets.only(right: 5.0)), const EdgeInsetsDirectional.only(end: 5.0).add(const EdgeInsets.only(right: 5.0)));
+    expect(const EdgeInsetsDirectional.only(end: 5.0).add(const EdgeInsets.only(right: 5.0)), isNot(const EdgeInsetsDirectional.only(end: 5.0).add(const EdgeInsets.only(left: 5.0))));
+    expect(const EdgeInsetsDirectional.only(top: 1.0).add(const EdgeInsets.only(top: 2.0)), const EdgeInsetsDirectional.only(top: 3.0).add(const EdgeInsets.only(top: 0.0)));
+    expect(const EdgeInsetsDirectional.only(top: 1.0).add(const EdgeInsets.only(top: 2.0)), const EdgeInsets.only(top: 3.0).add(const EdgeInsetsDirectional.only(top: 0.0)));
+    expect(const EdgeInsetsDirectional.only(top: 1.0).add(const EdgeInsets.only(top: 2.0)), const EdgeInsetsDirectional.only(top: 3.0));
+    expect(const EdgeInsetsDirectional.only(top: 1.0).add(const EdgeInsets.only(top: 2.0)), const EdgeInsets.only(top: 3.0));
  });

  test('EdgeInsetsGeometry.lerp(...)', () {
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(end: 10.0), null, 0.5), new EdgeInsetsDirectional.only(end: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(start: 10.0), null, 0.5), new EdgeInsetsDirectional.only(start: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(top: 10.0), null, 0.5), new EdgeInsetsDirectional.only(top: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(bottom: 10.0), null, 0.5), new EdgeInsetsDirectional.only(bottom: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(bottom: 10.0), EdgeInsetsDirectional.zero, 0.5), new EdgeInsetsDirectional.only(bottom: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(bottom: 10.0), EdgeInsets.zero, 0.5), new EdgeInsetsDirectional.only(bottom: 5.0));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(start: 10.0), new EdgeInsets.only(left: 20.0), 0.5), new EdgeInsetsDirectional.only(start: 5.0).add(new EdgeInsets.only(left: 10.0)));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsetsDirectional.only(start: 0.0, bottom: 1.0), new EdgeInsetsDirectional.only(start: 1.0, bottom: 1.0).add(new EdgeInsets.only(right: 2.0, bottom: 0.0)), 0.5), new EdgeInsetsDirectional.only(start: 0.5).add(new EdgeInsets.only(right: 1.0, bottom: 1.0)));
-    expect(EdgeInsetsGeometry.lerp(new EdgeInsets.only(left: 0.0, bottom: 1.0), new EdgeInsetsDirectional.only(end: 1.0, bottom: 1.0).add(new EdgeInsets.only(right: 2.0, bottom: 0.0)), 0.5), new EdgeInsetsDirectional.only(start: 0.0, end: 0.5).add(new EdgeInsets.only(right: 1.0, bottom: 1.0)));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(end: 10.0), null, 0.5), const EdgeInsetsDirectional.only(end: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(start: 10.0), null, 0.5), const EdgeInsetsDirectional.only(start: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(top: 10.0), null, 0.5), const EdgeInsetsDirectional.only(top: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(bottom: 10.0), null, 0.5), const EdgeInsetsDirectional.only(bottom: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(bottom: 10.0), EdgeInsetsDirectional.zero, 0.5), const EdgeInsetsDirectional.only(bottom: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(bottom: 10.0), EdgeInsets.zero, 0.5), const EdgeInsetsDirectional.only(bottom: 5.0));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(start: 10.0), const EdgeInsets.only(left: 20.0), 0.5), const EdgeInsetsDirectional.only(start: 5.0).add(const EdgeInsets.only(left: 10.0)));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsetsDirectional.only(start: 0.0, bottom: 1.0), const EdgeInsetsDirectional.only(start: 1.0, bottom: 1.0).add(const EdgeInsets.only(right: 2.0, bottom: 0.0)), 0.5), const EdgeInsetsDirectional.only(start: 0.5).add(const EdgeInsets.only(right: 1.0, bottom: 1.0)));
+    expect(EdgeInsetsGeometry.lerp(const EdgeInsets.only(left: 0.0, bottom: 1.0), const EdgeInsetsDirectional.only(end: 1.0, bottom: 1.0).add(const EdgeInsets.only(right: 2.0, bottom: 0.0)), 0.5), const EdgeInsetsDirectional.only(start: 0.0, end: 0.5).add(const EdgeInsets.only(right: 1.0, bottom: 1.0)));
  });

  test('EdgeInsetsGeometry.lerp(normal, ...)', () {
@ -168,7 +169,7 @@ void main() {

  test('EdgeInsetsGeometry operators', () {
    final EdgeInsetsGeometry a = const EdgeInsetsDirectional.fromSTEB(1.0, 2.0, 3.0, 5.0).add(EdgeInsets.zero);
-    expect(a, isNot(new isInstanceOf<EdgeInsetsDirectional>()));
+    expect(a, isNot(const isInstanceOf<EdgeInsetsDirectional>()));
    expect(a * 2.0, const EdgeInsetsDirectional.fromSTEB(2.0, 4.0, 6.0, 10.0));
    expect(a / 2.0, const EdgeInsetsDirectional.fromSTEB(0.5, 1.0, 1.5, 2.5));
    expect(a % 2.0, const EdgeInsetsDirectional.fromSTEB(1.0, 0.0, 1.0, 1.0));
@ -179,12 +180,12 @@ void main() {
  });

  test('EdgeInsetsGeometry toString', () {
-    expect(new EdgeInsets.only().toString(), 'EdgeInsets.zero');
-    expect(new EdgeInsets.only(top: 1.01, left: 1.01, right: 1.01, bottom: 1.01).toString(), 'EdgeInsets.all(1.0)');
-    expect(new EdgeInsetsDirectional.only().toString(), 'EdgeInsets.zero');
-    expect(new EdgeInsetsDirectional.only(start: 1.01, end: 1.01, top: 1.01, bottom: 1.01).toString(), 'EdgeInsetsDirectional(1.0, 1.0, 1.0, 1.0)');
-    expect((new EdgeInsetsDirectional.only(start: 4.0).add(new EdgeInsets.only(top: 3.0))).toString(), 'EdgeInsetsDirectional(4.0, 3.0, 0.0, 0.0)');
-    expect((new EdgeInsetsDirectional.only(top: 4.0).add(new EdgeInsets.only(right: 3.0))).toString(), 'EdgeInsets(0.0, 4.0, 3.0, 0.0)');
-    expect((new EdgeInsetsDirectional.only(start: 4.0).add(new EdgeInsets.only(left: 3.0))).toString(), 'EdgeInsets(3.0, 0.0, 0.0, 0.0) + EdgeInsetsDirectional(4.0, 0.0, 0.0, 0.0)');
+    expect(const EdgeInsets.only().toString(), 'EdgeInsets.zero');
+    expect(const EdgeInsets.only(top: 1.01, left: 1.01, right: 1.01, bottom: 1.01).toString(), 'EdgeInsets.all(1.0)');
+    expect(const EdgeInsetsDirectional.only().toString(), 'EdgeInsets.zero');
+    expect(const EdgeInsetsDirectional.only(start: 1.01, end: 1.01, top: 1.01, bottom: 1.01).toString(), 'EdgeInsetsDirectional(1.0, 1.0, 1.0, 1.0)');
+    expect((const EdgeInsetsDirectional.only(start: 4.0).add(const EdgeInsets.only(top: 3.0))).toString(), 'EdgeInsetsDirectional(4.0, 3.0, 0.0, 0.0)');
+    expect((const EdgeInsetsDirectional.only(top: 4.0).add(const EdgeInsets.only(right: 3.0))).toString(), 'EdgeInsets(0.0, 4.0, 3.0, 0.0)');
+    expect((const EdgeInsetsDirectional.only(start: 4.0).add(const EdgeInsets.only(left: 3.0))).toString(), 'EdgeInsets(3.0, 0.0, 0.0, 0.0) + EdgeInsetsDirectional(4.0, 0.0, 0.0, 0.0)');
  });
 }
--- a/packages/flutter/test/painting/fractional_offset_test.dart
+++ b/packages/flutter/test/painting/fractional_offset_test.dart
@ -25,8 +25,8 @@ void main() {
    expect(FractionalOffset.lerp(a, b, 0.25), equals(const FractionalOffset(0.125, 0.0)));

    expect(FractionalOffset.lerp(null, null, 0.25), isNull);
-    expect(FractionalOffset.lerp(null, b, 0.25), equals(new FractionalOffset(0.5, 0.5 - 0.125)));
-    expect(FractionalOffset.lerp(a, null, 0.25), equals(new FractionalOffset(0.125, 0.125)));
+    expect(FractionalOffset.lerp(null, b, 0.25), equals(const FractionalOffset(0.5, 0.5 - 0.125)));
+    expect(FractionalOffset.lerp(a, null, 0.25), equals(const FractionalOffset(0.125, 0.125)));
  });

  test('FractionalOffset.fromOffsetAndSize()', () {
@ -40,26 +40,27 @@ void main() {
  });

  test('FractionalOffsetGeometry.resolve()', () {
-    expect(new FractionalOffsetDirectional(0.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(0.25, 0.3));
-    expect(new FractionalOffsetDirectional(0.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(0.75, 0.3));
-    expect(new FractionalOffsetDirectional(-0.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(-0.25, 0.3));
-    expect(new FractionalOffsetDirectional(-0.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(1.25, 0.3));
-    expect(new FractionalOffsetDirectional(1.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(1.25, 0.3));
-    expect(new FractionalOffsetDirectional(1.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(-0.25, 0.3));
-    expect(new FractionalOffsetDirectional(0.5, -0.3).resolve(TextDirection.ltr), const FractionalOffset(0.5, -0.3));
-    expect(new FractionalOffsetDirectional(0.5, -0.3).resolve(TextDirection.rtl), const FractionalOffset(0.5, -0.3));
-    expect(new FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr), const FractionalOffset(0.0, 0.0));
-    expect(new FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.rtl), const FractionalOffset(1.0, 0.0));
-    expect(new FractionalOffsetDirectional(1.0, 1.0).resolve(TextDirection.ltr), const FractionalOffset(1.0, 1.0));
-    expect(new FractionalOffsetDirectional(1.0, 1.0).resolve(TextDirection.rtl), const FractionalOffset(0.0, 1.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0), new FractionalOffsetDirectional(1.0, 2.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0).hashCode, isNot(new FractionalOffsetDirectional(2.0, 1.0)));
-    expect(new FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr),
-           new FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.rtl));
-    expect(new FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr),
-     isNot(new FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.ltr)));
-    expect(new FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.ltr),
-     isNot(new FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.rtl)));
+    expect(const FractionalOffsetDirectional(0.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(0.25, 0.3));
+    expect(const FractionalOffsetDirectional(0.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(0.75, 0.3));
+    expect(const FractionalOffsetDirectional(-0.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(-0.25, 0.3));
+    expect(const FractionalOffsetDirectional(-0.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(1.25, 0.3));
+    expect(const FractionalOffsetDirectional(1.25, 0.3).resolve(TextDirection.ltr), const FractionalOffset(1.25, 0.3));
+    expect(const FractionalOffsetDirectional(1.25, 0.3).resolve(TextDirection.rtl), const FractionalOffset(-0.25, 0.3));
+    expect(const FractionalOffsetDirectional(0.5, -0.3).resolve(TextDirection.ltr), const FractionalOffset(0.5, -0.3));
+    expect(const FractionalOffsetDirectional(0.5, -0.3).resolve(TextDirection.rtl), const FractionalOffset(0.5, -0.3));
+    expect(const FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr), const FractionalOffset(0.0, 0.0));
+    expect(const FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.rtl), const FractionalOffset(1.0, 0.0));
+    expect(const FractionalOffsetDirectional(1.0, 1.0).resolve(TextDirection.ltr), const FractionalOffset(1.0, 1.0));
+    expect(const FractionalOffsetDirectional(1.0, 1.0).resolve(TextDirection.rtl), const FractionalOffset(0.0, 1.0));
+    final double $1 = 1.0; // we want these instances to be separate instances so that we're not just checking with a single object
+    expect(new FractionalOffsetDirectional($1, 2.0), new FractionalOffsetDirectional($1, 2.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0), isNot(const FractionalOffsetDirectional(2.0, 1.0)));
+    expect(const FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr),
+           const FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.rtl));
+    expect(const FractionalOffsetDirectional(0.0, 0.0).resolve(TextDirection.ltr),
+     isNot(const FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.ltr)));
+    expect(const FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.ltr),
+     isNot(const FractionalOffsetDirectional(1.0, 0.0).resolve(TextDirection.rtl)));
  });

  test('FractionalOffsetGeometry.lerp', () {
@ -111,34 +112,34 @@ void main() {
  });

  test('FractionalOffsetGeometry operators', () {
-    expect(new FractionalOffsetDirectional(1.0, 2.0) * 2.0, new FractionalOffsetDirectional(2.0, 4.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0) / 2.0, new FractionalOffsetDirectional(0.5, 1.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0) % 2.0, new FractionalOffsetDirectional(1.0, 0.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0) ~/ 2.0, new FractionalOffsetDirectional(0.0, 1.0));
-    expect(FractionalOffset.topLeft.add(new FractionalOffsetDirectional(1.0, 2.0) * 2.0), new FractionalOffsetDirectional(2.0, 4.0));
-    expect(FractionalOffset.topLeft.add(new FractionalOffsetDirectional(1.0, 2.0) / 2.0), new FractionalOffsetDirectional(0.5, 1.0));
-    expect(FractionalOffset.topLeft.add(new FractionalOffsetDirectional(1.0, 2.0) % 2.0), new FractionalOffsetDirectional(1.0, 0.0));
-    expect(FractionalOffset.topLeft.add(new FractionalOffsetDirectional(1.0, 2.0) ~/ 2.0), new FractionalOffsetDirectional(0.0, 1.0));
-    expect(new FractionalOffset(1.0, 2.0) * 2.0, new FractionalOffset(2.0, 4.0));
-    expect(new FractionalOffset(1.0, 2.0) / 2.0, new FractionalOffset(0.5, 1.0));
-    expect(new FractionalOffset(1.0, 2.0) % 2.0, new FractionalOffset(1.0, 0.0));
-    expect(new FractionalOffset(1.0, 2.0) ~/ 2.0, new FractionalOffset(0.0, 1.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) * 2.0, const FractionalOffsetDirectional(2.0, 4.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) / 2.0, const FractionalOffsetDirectional(0.5, 1.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) % 2.0, const FractionalOffsetDirectional(1.0, 0.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) ~/ 2.0, const FractionalOffsetDirectional(0.0, 1.0));
+    expect(FractionalOffset.topLeft.add(const FractionalOffsetDirectional(1.0, 2.0) * 2.0), const FractionalOffsetDirectional(2.0, 4.0));
+    expect(FractionalOffset.topLeft.add(const FractionalOffsetDirectional(1.0, 2.0) / 2.0), const FractionalOffsetDirectional(0.5, 1.0));
+    expect(FractionalOffset.topLeft.add(const FractionalOffsetDirectional(1.0, 2.0) % 2.0), const FractionalOffsetDirectional(1.0, 0.0));
+    expect(FractionalOffset.topLeft.add(const FractionalOffsetDirectional(1.0, 2.0) ~/ 2.0), const FractionalOffsetDirectional(0.0, 1.0));
+    expect(const FractionalOffset(1.0, 2.0) * 2.0, const FractionalOffset(2.0, 4.0));
+    expect(const FractionalOffset(1.0, 2.0) / 2.0, const FractionalOffset(0.5, 1.0));
+    expect(const FractionalOffset(1.0, 2.0) % 2.0, const FractionalOffset(1.0, 0.0));
+    expect(const FractionalOffset(1.0, 2.0) ~/ 2.0, const FractionalOffset(0.0, 1.0));
  });

  test('FractionalOffsetGeometry operators', () {
-    expect(new FractionalOffset(1.0, 2.0) + new FractionalOffset(3.0, 5.0), new FractionalOffset(4.0, 7.0));
-    expect(new FractionalOffset(1.0, 2.0) - new FractionalOffset(3.0, 5.0), new FractionalOffset(-2.0, -3.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0) + new FractionalOffsetDirectional(3.0, 5.0), new FractionalOffsetDirectional(4.0, 7.0));
-    expect(new FractionalOffsetDirectional(1.0, 2.0) - new FractionalOffsetDirectional(3.0, 5.0), new FractionalOffsetDirectional(-2.0, -3.0));
+    expect(const FractionalOffset(1.0, 2.0) + const FractionalOffset(3.0, 5.0), const FractionalOffset(4.0, 7.0));
+    expect(const FractionalOffset(1.0, 2.0) - const FractionalOffset(3.0, 5.0), const FractionalOffset(-2.0, -3.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) + const FractionalOffsetDirectional(3.0, 5.0), const FractionalOffsetDirectional(4.0, 7.0));
+    expect(const FractionalOffsetDirectional(1.0, 2.0) - const FractionalOffsetDirectional(3.0, 5.0), const FractionalOffsetDirectional(-2.0, -3.0));
  });

  test('FractionalOffsetGeometry toString', () {
-    expect(new FractionalOffset(1.0001, 2.0001).toString(), 'FractionalOffset(1.0, 2.0)');
-    expect(new FractionalOffset(0.0, 0.0).toString(), 'FractionalOffset.topLeft');
-    expect(new FractionalOffset(0.0, 1.0).add(new FractionalOffsetDirectional(1.0, 0.0)).toString(), 'FractionalOffsetDirectional.bottomEnd');
-    expect(new FractionalOffset(0.0001, 0.0001).toString(), 'FractionalOffset(0.0, 0.0)');
-    expect(new FractionalOffset(0.0, 0.0).toString(), 'FractionalOffset.topLeft');
-    expect(new FractionalOffsetDirectional(0.0, 0.0).toString(), 'FractionalOffsetDirectional.topStart');
-    expect(new FractionalOffset(1.0, 1.0).add(new FractionalOffsetDirectional(1.0, 1.0)).toString(), 'FractionalOffset(1.0, 2.0) + FractionalOffsetDirectional(1.0, 0.0)');
+    expect(const FractionalOffset(1.0001, 2.0001).toString(), 'FractionalOffset(1.0, 2.0)');
+    expect(const FractionalOffset(0.0, 0.0).toString(), 'FractionalOffset.topLeft');
+    expect(const FractionalOffset(0.0, 1.0).add(const FractionalOffsetDirectional(1.0, 0.0)).toString(), 'FractionalOffsetDirectional.bottomEnd');
+    expect(const FractionalOffset(0.0001, 0.0001).toString(), 'FractionalOffset(0.0, 0.0)');
+    expect(const FractionalOffset(0.0, 0.0).toString(), 'FractionalOffset.topLeft');
+    expect(const FractionalOffsetDirectional(0.0, 0.0).toString(), 'FractionalOffsetDirectional.topStart');
+    expect(const FractionalOffset(1.0, 1.0).add(const FractionalOffsetDirectional(1.0, 1.0)).toString(), 'FractionalOffset(1.0, 2.0) + FractionalOffsetDirectional(1.0, 0.0)');
  });
 }
--- a/packages/flutter/test/rendering/flex_test.dart
+++ b/packages/flutter/test/rendering/flex_test.dart
@ -358,7 +358,7 @@ void main() {
    expect(exceptions, isEmpty);
    layout(parent);
    expect(exceptions, isNotEmpty);
-    expect(exceptions.first, new isInstanceOf<FlutterError>());
+    expect(exceptions.first, const isInstanceOf<FlutterError>());
  });

  test('MainAxisSize.min inside unconstrained', () {
@ -388,7 +388,7 @@ void main() {
    expect(exceptions, isEmpty);
    layout(parent);
    expect(exceptions, isNotEmpty);
-    expect(exceptions.first, new isInstanceOf<FlutterError>());
+    expect(exceptions.first, const isInstanceOf<FlutterError>());
  });

  test('Flex RTL', () {
--- a/packages/flutter/test/services/image_provider_test.dart
+++ b/packages/flutter/test/services/image_provider_test.dart
@ -8,7 +8,8 @@ import 'package:flutter_test/flutter_test.dart';
 void main() {
  test('NetworkImage non-null url test', () {
    expect(() {
-      new NetworkImage(null); // ignore: prefer_const_constructors
+      final String url = null; // we don't want this instance to be const because otherwise it would throw at compile time.
+      new NetworkImage(url);
    }, throwsAssertionError);
  });
 }
--- a/packages/flutter/test/widgets/directionality_test.dart
+++ b/packages/flutter/test/widgets/directionality_test.dart
@ -11,7 +11,7 @@ void main() {
    final Widget inner = new Builder(
      builder: (BuildContext context) {
        log.add(Directionality.of(context));
-        return new Placeholder();
+        return const Placeholder();
      }
    );
    await tester.pumpWidget(
@ -57,13 +57,16 @@ void main() {
      builder: (BuildContext context) {
        expect(Directionality.of(context), isNull);
        good = true;
-        return new Placeholder();
+        return const Placeholder();
      },
    ));
    expect(good, isTrue);
  });

  testWidgets('Directionality can\'t be null', (WidgetTester tester) async {
-    expect(() { new Directionality(textDirection: null, child: new Placeholder()); }, throwsAssertionError);
+    expect(() {
+      final TextDirection textDirection = null; // we don't want this instance to be const because otherwise it would throw at compile time.
+      new Directionality(textDirection: textDirection, child: const Placeholder());
+    }, throwsAssertionError);
  });
 }
--- a/packages/flutter/test/widgets/localizations_test.dart
+++ b/packages/flutter/test/widgets/localizations_test.dart
@ -130,7 +130,7 @@ void main() {
      buildFrame(
        buildContent: (BuildContext context) {
          pageContext = context;
-          return new Text('Hello World');
+          return const Text('Hello World');
        }
      )
    );
@ -153,7 +153,7 @@ void main() {
        locale: locale,
        buildContent: (BuildContext context) {
          pageContext = context;
-          return new Text('Hello World');
+          return const Text('Hello World');
        },
      )
    );
@ -295,7 +295,7 @@ void main() {
                locale: const Locale('en', 'GB'),
                delegates: <LocalizationsDelegate<dynamic>>[
                  new SyncTestLocalizationsDelegate(),
-                  new DefaultWidgetsLocalizationsDelegate(),
+                  const DefaultWidgetsLocalizationsDelegate(),
                ],
                // Create a new context within the en_GB Localization
                child: new Builder(
--- a/packages/flutter/test/widgets/rtl_test.dart
+++ b/packages/flutter/test/widgets/rtl_test.dart
@ -7,9 +7,9 @@ import 'package:flutter/widgets.dart';

 void main() {
  testWidgets('Padding RTL', (WidgetTester tester) async {
-    final Widget child = new Padding(
-      padding: new EdgeInsetsDirectional.only(start: 10.0),
-      child: new Placeholder(),
+    final Widget child = const Padding(
+      padding: const EdgeInsetsDirectional.only(start: 10.0),
+      child: const Placeholder(),
    );
    await tester.pumpWidget(new Directionality(
      textDirection: TextDirection.ltr,
@ -25,9 +25,9 @@ void main() {

  testWidgets('Container padding/margin RTL', (WidgetTester tester) async {
    final Widget child = new Container(
-      padding: new EdgeInsetsDirectional.only(start: 6.0),
-      margin: new EdgeInsetsDirectional.only(end: 20.0, start: 4.0),
-      child: new Placeholder(),
+      padding: const EdgeInsetsDirectional.only(start: 6.0),
+      margin: const EdgeInsetsDirectional.only(end: 20.0, start: 4.0),
+      child: const Placeholder(),
    );
    await tester.pumpWidget(new Directionality(
      textDirection: TextDirection.ltr,
@ -45,9 +45,9 @@ void main() {

  testWidgets('Container padding/margin mixed RTL/absolute', (WidgetTester tester) async {
    final Widget child = new Container(
-      padding: new EdgeInsets.only(left: 6.0),
-      margin: new EdgeInsetsDirectional.only(end: 20.0, start: 4.0),
-      child: new Placeholder(),
+      padding: const EdgeInsets.only(left: 6.0),
+      margin: const EdgeInsetsDirectional.only(end: 20.0, start: 4.0),
+      child: const Placeholder(),
    );
    await tester.pumpWidget(new Directionality(
      textDirection: TextDirection.ltr,
@ -64,7 +64,7 @@ void main() {
  });

  testWidgets('EdgeInsetsDirectional without Directionality', (WidgetTester tester) async {
-    await tester.pumpWidget(new Padding(padding: new EdgeInsetsDirectional.only()));
+    await tester.pumpWidget(const Padding(padding: const EdgeInsetsDirectional.only()));
    expect(tester.takeException(), isAssertionError);
  });
 }
--- a/packages/flutter/test/widgets/semantics_10_test.dart
+++ b/packages/flutter/test/widgets/semantics_10_test.dart
@ -51,10 +51,10 @@ Widget buildTestWidgets({bool excludeSemantics, String label, bool isSemanticsBo
        isSemanticBoundary: isSemanticsBoundary,
        child: new Column(
          children: <Widget>[
-            new Semantics(
+            const Semantics(
              label: 'child1',
            ),
-            new Semantics(
+            const Semantics(
              label: 'child2',
            ),
          ],
--- a/packages/flutter/test/widgets/semantics_11_test.dart
+++ b/packages/flutter/test/widgets/semantics_11_test.dart
@ -13,7 +13,7 @@ void main() {
  testWidgets('markNeedsSemanticsUpdate allways resets node', (WidgetTester tester) async {
    final SemanticsTester semantics = new SemanticsTester(tester);

-    await tester.pumpWidget(new TestWidget());
+    await tester.pumpWidget(const TestWidget());
    final RenderTest renderObj = tester.renderObject(find.byType(TestWidget));
    expect(renderObj.labelWasReset, hasLength(1));
    expect(renderObj.labelWasReset.last, true);
--- a/packages/flutter/test/widgets/sliver_semantics_test.dart
+++ b/packages/flutter/test/widgets/sliver_semantics_test.dart
@ -29,7 +29,7 @@ void main() {
        child: new CustomScrollView(
          controller: scrollController,
          slivers: <Widget>[
-            new SliverAppBar(
+            const SliverAppBar(
              pinned: true,
              expandedHeight: appBarExpandedHeight,
              title: const Text('Semantics Test with Slivers'),
@ -239,7 +239,7 @@ void main() {
        slivers: slivers,
      ),
    );
-    
+
    expect(semantics, hasSemantics(
      new TestSemantics.root(
        children: <TestSemantics>[
@ -295,10 +295,10 @@ void main() {
    final ScrollController controller = new ScrollController(initialScrollOffset: 280.0);
    await tester.pumpWidget(
      new MediaQuery(
-        data: new MediaQueryData(),
+        data: const MediaQueryData(),
        child: new CustomScrollView(
          slivers: <Widget>[
-            new SliverAppBar(
+            const SliverAppBar(
              pinned: true,
              expandedHeight: 100.0,
            ),
@ -377,11 +377,11 @@ void main() {
    });
    await tester.pumpWidget(
      new MediaQuery(
-        data: new MediaQueryData(),
+        data: const MediaQueryData(),
        child: new CustomScrollView(
          controller: controller,
          slivers: <Widget>[
-            new SliverAppBar(
+            const SliverAppBar(
              pinned: true,
              expandedHeight: 100.0,
            ),
@ -454,11 +454,11 @@ void main() {
    final ScrollController controller = new ScrollController(initialScrollOffset: 280.0);
    await tester.pumpWidget(
      new MediaQuery(
-        data: new MediaQueryData(),
+        data: const MediaQueryData(),
        child: new CustomScrollView(
          reverse: true,  // This is the important setting for this test.
          slivers: <Widget>[
-            new SliverAppBar(
+            const SliverAppBar(
              pinned: true,
              expandedHeight: 100.0,
            ),
@ -538,12 +538,12 @@ void main() {
    });
    await tester.pumpWidget(
      new MediaQuery(
-        data: new MediaQueryData(),
+        data: const MediaQueryData(),
        child: new CustomScrollView(
          reverse: true,  // This is the important setting for this test.
          controller: controller,
          slivers: <Widget>[
-            new SliverAppBar(
+            const SliverAppBar(
              pinned: true,
              expandedHeight: 100.0,
            ),
@ -624,7 +624,7 @@ void main() {
    });
    await tester.pumpWidget(
      new MediaQuery(
-        data: new MediaQueryData(),
+        data: const MediaQueryData(),
        child: new Scrollable(
          controller: controller,
          viewportBuilder: (BuildContext context, ViewportOffset offset) {
@ -635,7 +635,7 @@ void main() {
                new SliverList(
                  delegate: new SliverChildListDelegate(backwardChildren),
                ),
-                new SliverAppBar(
+                const SliverAppBar(
                  pinned: true,
                  expandedHeight: 100.0,
                  flexibleSpace: const FlexibleSpaceBar(
--- a/packages/flutter_tools/test/ios/devices_test.dart
+++ b/packages/flutter_tools/test/ios/devices_test.dart
@ -90,7 +90,7 @@ iPhone SE (11.0) [667E8DCD-5DCD-4C80-93A9-60D1D995206F] (Simulator)
  Runner(libsystem_asl.dylib)[297] <Notice>: libMobileGestalt MobileGestalt.c:550: no access to InverseDeviceID (see <rdar://problem/11744455>)
  Runner(libsystem_asl.dylib)[297] <Notice>: I is for ichigo
  '''.codeUnits]));
-        when(mockProcess.stderr).thenReturn(new Stream<List<int>>.empty());
+        when(mockProcess.stderr).thenReturn(const Stream<List<int>>.empty());
        // Delay return of exitCode until after stdout stream data, since it terminates the logger.
        when(mockProcess.exitCode).thenReturn(new Future<int>.delayed(Duration.ZERO, () => 0));
        return new Future<Process>.value(mockProcess);