diff --git a/analysis_options.yaml b/analysis_options.yaml
index 4a4006398a..823215daa7 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -42,6 +42,7 @@ analyzer:
     # see https://github.com/dart-lang/sdk/issues/28463
     - "lib/i18n/messages_*.dart"
     - "lib/src/http/**"
+    - "test_fixes/**"
 
 linter:
   rules:
diff --git a/dev/bots/test.dart b/dev/bots/test.dart
index 2ac702a1d4..2a9d49f27c 100644
--- a/dev/bots/test.dart
+++ b/dev/bots/test.dart
@@ -644,6 +644,18 @@ Future<void> _runFrameworkTests() async {
     }
   }
 
+  Future<void> runFixTests() async {
+    final List<String> args = <String>[
+      'fix',
+      '--compare-to-golden',
+    ];
+    await runCommand(
+      dart,
+      args,
+      workingDirectory: path.join(flutterRoot, 'packages', 'flutter', 'test_fixes'),
+    );
+  }
+
   Future<void> runPrivateTests() async {
     final List<String> args = <String>[
       'run',
@@ -702,6 +714,7 @@ Future<void> _runFrameworkTests() async {
       options: <String>['--enable-vmservice'],
       tableData: bigqueryApi?.tabledata,
     );
+    await runFixTests();
     await runPrivateTests();
     const String httpClientWarning =
       'Warning: At least one test in this suite creates an HttpClient. When\n'
diff --git a/packages/flutter/lib/fix_data.yaml b/packages/flutter/lib/fix_data.yaml
new file mode 100644
index 0000000000..cf74e8612a
--- /dev/null
+++ b/packages/flutter/lib/fix_data.yaml
@@ -0,0 +1,36 @@
+# Copyright 2014 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# TODO(Piinks): Add link to public user guide when available.
+
+# Please add new fixes to the top of the file, separated by one blank line
+# from other fixes. In a comment, include a link to the PR where the change
+# requiring the fix was made.
+
+version: 1
+transforms:
+
+  # Changes made in https://github.com/flutter/flutter/pull/41859
+  - title: 'Remove brightness'
+    date: 2020-12-10
+    element:
+      uris: [ 'cupertino.dart' ]
+      constructor: ''
+      inClass: 'CupertinoTextThemeData'
+    changes:
+      - kind: 'removeParameter'
+        name: 'brightness'
+
+  # Changes made in https://github.com/flutter/flutter/pull/41859
+  - title: 'Remove brightness'
+    date: 2020-12-10
+    element:
+      uris: [ 'cupertino.dart' ]
+      method: 'copyWith'
+      inClass: 'CupertinoTextThemeData'
+    changes:
+      - kind: 'removeParameter'
+        name: 'brightness'
+
+# Before adding a new fix: read instructions at the top of this file.
diff --git a/packages/flutter/lib/src/cupertino/text_theme.dart b/packages/flutter/lib/src/cupertino/text_theme.dart
index 77f0b92334..d632f49c95 100644
--- a/packages/flutter/lib/src/cupertino/text_theme.dart
+++ b/packages/flutter/lib/src/cupertino/text_theme.dart
@@ -124,12 +124,6 @@ class CupertinoTextThemeData with Diagnosticable {
   /// unspecified.
   const CupertinoTextThemeData({
     Color primaryColor = CupertinoColors.systemBlue,
-    // ignore: avoid_unused_constructor_parameters, the parameter is deprecated.
-    @Deprecated(
-      'This argument no longer does anything. You can remove it. '
-      'This feature was deprecated after v1.10.14.'
-    )
-    Brightness? brightness,
     TextStyle? textStyle,
     TextStyle? actionTextStyle,
     TextStyle? tabLabelTextStyle,
@@ -230,11 +224,6 @@ class CupertinoTextThemeData with Diagnosticable {
   /// specified overrides.
   CupertinoTextThemeData copyWith({
     Color? primaryColor,
-    @Deprecated(
-      'This argument no longer does anything. You can remove it. '
-      'This feature was deprecated after v1.10.14.'
-    )
-    Brightness? brightness,
     TextStyle? textStyle,
     TextStyle? actionTextStyle,
     TextStyle? tabLabelTextStyle,
diff --git a/packages/flutter/test_fixes/.dartignore b/packages/flutter/test_fixes/.dartignore
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/flutter/test_fixes/analysis_options.yaml b/packages/flutter/test_fixes/analysis_options.yaml
new file mode 100644
index 0000000000..7cca7b1d5c
--- /dev/null
+++ b/packages/flutter/test_fixes/analysis_options.yaml
@@ -0,0 +1 @@
+# This ensures that parent analysis options do not accidentally break the fix tests.
diff --git a/packages/flutter/test_fixes/cupertino.dart b/packages/flutter/test_fixes/cupertino.dart
new file mode 100644
index 0000000000..43a88c199c
--- /dev/null
+++ b/packages/flutter/test_fixes/cupertino.dart
@@ -0,0 +1,11 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/cupertino.dart';
+
+void main() {
+  // Change made in https://github.com/flutter/flutter/pull/41859
+  const CupertinoTextThemeData themeData = CupertinoTextThemeData(brightness: Brightness.dark);
+  themeData.copyWith(brightness: Brightness.light);
+}
diff --git a/packages/flutter/test_fixes/cupertino.dart.expect b/packages/flutter/test_fixes/cupertino.dart.expect
new file mode 100644
index 0000000000..aa6b9fa58c
--- /dev/null
+++ b/packages/flutter/test_fixes/cupertino.dart.expect
@@ -0,0 +1,11 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/cupertino.dart';
+
+void main() {
+  // Change made in https://github.com/flutter/flutter/pull/41859
+  const CupertinoTextThemeData themeData = CupertinoTextThemeData();
+  themeData.copyWith();
+}