Animate TextStyle.fontVariations (#138881)

Fixes https://github.com/flutter/flutter/issues/105120

I also exposed the relevant dart:ui types which had the effect of removing a large number of dart:ui imports from examples.

examples/api/lib/ui/text/font_feature.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/material.dart';
 
 /// Flutter code sample for [FontFeature].

examples/api/lib/ui/text/font_feature.font_feature_alternative.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.alternative].

examples/api/lib/ui/text/font_feature.font_feature_alternative_fractions.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.alternativeFractions].

examples/api/lib/ui/text/font_feature.font_feature_case_sensitive_forms.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.caseSensitiveForms].

examples/api/lib/ui/text/font_feature.font_feature_character_variant.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.characterVariant].

examples/api/lib/ui/text/font_feature.font_feature_contextual_alternates.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.contextualAlternates].

examples/api/lib/ui/text/font_feature.font_feature_denominator.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.denominator].

examples/api/lib/ui/text/font_feature.font_feature_fractions.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.fractions].

examples/api/lib/ui/text/font_feature.font_feature_historical_forms.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.historicalForms].

examples/api/lib/ui/text/font_feature.font_feature_historical_ligatures.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.historicalLigatures].

examples/api/lib/ui/text/font_feature.font_feature_lining_figures.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.liningFigures].

examples/api/lib/ui/text/font_feature.font_feature_notational_forms.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.notationalForms].

examples/api/lib/ui/text/font_feature.font_feature_numerators.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.numerators].

examples/api/lib/ui/text/font_feature.font_feature_oldstyle_figures.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.oldstyleFigures].

examples/api/lib/ui/text/font_feature.font_feature_ordinal_forms.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.ordinalForms].

examples/api/lib/ui/text/font_feature.font_feature_proportional_figures.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.proportionalFigures].

examples/api/lib/ui/text/font_feature.font_feature_scientific_inferiors.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.scientificInferiors].

examples/api/lib/ui/text/font_feature.font_feature_slashed_zero.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.slashedZero].

examples/api/lib/ui/text/font_feature.font_feature_stylistic_alternates.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.stylisticAlternates].

examples/api/lib/ui/text/font_feature.font_feature_stylistic_set.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.stylisticSet].

examples/api/lib/ui/text/font_feature.font_feature_stylistic_set.1.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.stylisticSet].

examples/api/lib/ui/text/font_feature.font_feature_subscripts.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.subscripts].

examples/api/lib/ui/text/font_feature.font_feature_superscripts.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.superscripts].

examples/api/lib/ui/text/font_feature.font_feature_swash.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [FontFeature.FontFeature.swash].

examples/api/lib/ui/text/font_feature.font_feature_tabular_figures.0.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/widgets.dart';
 
 /// Flutter code sample for [dart]:ui FontFeature.FontFeature.tabularFigures.

examples/api/test/ui/text/font_feature.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_alternative.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_alternative.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_alternative_fractions.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_alternative_fractions.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_case_sensitive_forms.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_case_sensitive_forms.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_character_variant.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_character_variant.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_contextual_alternates.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_contextual_alternates.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_denominator.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_denominator.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_fractions.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_fractions.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_historical_forms.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_historical_forms.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_historical_ligatures.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_historical_ligatures.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_lining_figures.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_lining_figures.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_notational_forms.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_notational_forms.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_numerators.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_numerators.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_oldstyle_figures.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_oldstyle_figures.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_ordinal_forms.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_ordinal_forms.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_proportional_figures.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_proportional_figures.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_scientific_inferiors.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_scientific_inferiors.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_slashed_zero.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_slashed_zero.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_stylistic_alternates.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_stylistic_alternates.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_stylistic_set.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_stylistic_set.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_stylistic_set.1_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_stylistic_set.1.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_subscripts.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_subscripts.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_superscripts.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_superscripts.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_swash.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_swash.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

examples/api/test/ui/text/font_feature.font_feature_tabular_figures.0_test.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
 import 'package:flutter/material.dart';
 import 'package:flutter_api_samples/ui/text/font_feature.font_feature_tabular_figures.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';

packages/flutter/lib/src/painting/basic_types.dart

@@ -12,7 +12,9 @@ export 'dart:ui' show
   Color,
   ColorFilter,
   FilterQuality,
+  FontFeature,
   FontStyle,
+  FontVariation,
   FontWeight,
   ImageShader,
   Locale,
@@ -28,6 +30,7 @@ export 'dart:ui' show
   Radius,
   Rect,
   Shader,
+  Shadow,
   Size,
   StrokeCap,
   StrokeJoin,
@@ -38,6 +41,8 @@ export 'dart:ui' show
   TextDecoration,
   TextDecorationStyle,
   TextDirection,
+  TextHeightBehavior,
+  TextLeadingDistribution,
   TextPosition,
   TileMode,
   VertexMode,

packages/flutter/lib/src/painting/strut_style.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' show TextLeadingDistribution;
-
 import 'package:flutter/foundation.dart';
 
 import 'basic_types.dart';

packages/flutter/lib/src/painting/text_painter.dart

@@ -12,7 +12,6 @@ import 'dart:ui' as ui show
   ParagraphConstraints,
   ParagraphStyle,
   PlaceholderAlignment,
-  TextHeightBehavior,
   TextStyle;
 
 import 'package:flutter/foundation.dart';
@@ -488,7 +487,7 @@ class TextPainter {
     Locale? locale,
     StrutStyle? strutStyle,
     TextWidthBasis textWidthBasis = TextWidthBasis.parent,
-    ui.TextHeightBehavior? textHeightBehavior,
+    TextHeightBehavior? textHeightBehavior,
   }) : assert(text == null || text.debugAssertIsValid()),
        assert(maxLines == null || maxLines > 0),
        assert(textScaleFactor == 1.0 || identical(textScaler, TextScaler.noScaling), 'Use textScaler instead.'),
@@ -537,7 +536,7 @@ class TextPainter {
     Locale? locale,
     StrutStyle? strutStyle,
     TextWidthBasis textWidthBasis = TextWidthBasis.parent,
-    ui.TextHeightBehavior? textHeightBehavior,
+    TextHeightBehavior? textHeightBehavior,
     double minWidth = 0.0,
     double maxWidth = double.infinity,
   }) {
@@ -589,7 +588,7 @@ class TextPainter {
     Locale? locale,
     StrutStyle? strutStyle,
     TextWidthBasis textWidthBasis = TextWidthBasis.parent,
-    ui.TextHeightBehavior? textHeightBehavior,
+    TextHeightBehavior? textHeightBehavior,
     double minWidth = 0.0,
     double maxWidth = double.infinity,
   }) {
@@ -894,9 +893,9 @@ class TextPainter {
   }
 
   /// {@macro dart.ui.textHeightBehavior}
-  ui.TextHeightBehavior? get textHeightBehavior => _textHeightBehavior;
-  ui.TextHeightBehavior? _textHeightBehavior;
-  set textHeightBehavior(ui.TextHeightBehavior? value) {
+  TextHeightBehavior? get textHeightBehavior => _textHeightBehavior;
+  TextHeightBehavior? _textHeightBehavior;
+  set textHeightBehavior(TextHeightBehavior? value) {
     if (_textHeightBehavior == value) {
       return;
     }

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

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 

packages/flutter/test/painting/text_style_test.dart

@@ -595,4 +595,63 @@ void main() {
     expect(TextStyle.lerp(fromStyle, toStyle, 1), toStyle);
   });
 
+  test('lerpFontVariations', () {
+    // nil cases
+    expect(lerpFontVariations(const <FontVariation>[], const <FontVariation>[], 0.0), const <FontVariation>[]);
+    expect(lerpFontVariations(const <FontVariation>[], const <FontVariation>[], 0.5), const <FontVariation>[]);
+    expect(lerpFontVariations(const <FontVariation>[], const <FontVariation>[], 1.0), const <FontVariation>[]);
+    expect(lerpFontVariations(null, const <FontVariation>[], 0.0), null);
+    expect(lerpFontVariations(const <FontVariation>[], null, 0.0), const <FontVariation>[]);
+    expect(lerpFontVariations(null, null, 0.0), null);
+    expect(lerpFontVariations(null, const <FontVariation>[], 0.5), const <FontVariation>[]);
+    expect(lerpFontVariations(const <FontVariation>[], null, 0.5), null);
+    expect(lerpFontVariations(null, null, 0.5), null);
+    expect(lerpFontVariations(null, const <FontVariation>[], 1.0), const <FontVariation>[]);
+    expect(lerpFontVariations(const <FontVariation>[], null, 1.0), null);
+    expect(lerpFontVariations(null, null, 1.0), null);
+
+    const FontVariation w100 = FontVariation.weight(100.0);
+    const FontVariation w120 = FontVariation.weight(120.0);
+    const FontVariation w150 = FontVariation.weight(150.0);
+    const FontVariation w200 = FontVariation.weight(200.0);
+    const FontVariation w300 = FontVariation.weight(300.0);
+    const FontVariation w1000 = FontVariation.weight(1000.0);
+
+    // one axis
+    expect(lerpFontVariations(const <FontVariation>[w100], const <FontVariation>[w200], 0.0), const <FontVariation>[w100]);
+    expect(lerpFontVariations(const <FontVariation>[w100], const <FontVariation>[w200], 0.2), const <FontVariation>[w120]);
+    expect(lerpFontVariations(const <FontVariation>[w100], const <FontVariation>[w200], 0.5), const <FontVariation>[w150]);
+    expect(lerpFontVariations(const <FontVariation>[w100], const <FontVariation>[w200], 2.0), const <FontVariation>[w300]);
+
+    // weird one axis cases
+    expect(lerpFontVariations(const <FontVariation>[w100, w1000], const <FontVariation>[w300], 0.0), const <FontVariation>[w100, w1000]);
+    expect(lerpFontVariations(const <FontVariation>[w100, w1000], const <FontVariation>[w300], 0.5), const <FontVariation>[w200]);
+    expect(lerpFontVariations(const <FontVariation>[w100, w1000], const <FontVariation>[w300], 1.0), const <FontVariation>[w300]);
+    expect(lerpFontVariations(const <FontVariation>[w100, w1000], const <FontVariation>[], 0.5), const <FontVariation>[]);
+
+    const FontVariation sn80 = FontVariation.slant(-80.0);
+    const FontVariation sn40 = FontVariation.slant(-40.0);
+    const FontVariation s0 = FontVariation.slant(0.0);
+    const FontVariation sp40 = FontVariation.slant(40.0);
+    const FontVariation sp80 = FontVariation.slant(80.0);
+
+    // two axis matched order
+    expect(lerpFontVariations(const <FontVariation>[w100, sn80], const <FontVariation>[w300, sp80], 0.5), const <FontVariation>[w200, s0]);
+
+    // two axis unmatched order
+    expect(lerpFontVariations(const <FontVariation>[sn80, w100], const <FontVariation>[w300, sp80], 0.0), const <FontVariation>[sn80, w100]);
+    expect(lerpFontVariations(const <FontVariation>[sn80, w100], const <FontVariation>[w300, sp80], 0.5), unorderedMatches(const <FontVariation>[s0, w200]));
+    expect(lerpFontVariations(const <FontVariation>[sn80, w100], const <FontVariation>[w300, sp80], 1.0), const <FontVariation>[w300, sp80]);
+
+    // two axis with duplicates
+    expect(lerpFontVariations(const <FontVariation>[sn80, w100, sp80], const <FontVariation>[w300, sp80], 0.5), unorderedMatches(const <FontVariation>[sp80, w200]));
+
+    // mixed axis counts
+    expect(lerpFontVariations(const <FontVariation>[sn80, w100], const <FontVariation>[w300], 0.5), const <FontVariation>[w200]);
+    expect(lerpFontVariations(const <FontVariation>[sn80], const <FontVariation>[w300], 0.0), const <FontVariation>[sn80]);
+    expect(lerpFontVariations(const <FontVariation>[sn80], const <FontVariation>[w300], 0.1), const <FontVariation>[sn80]);
+    expect(lerpFontVariations(const <FontVariation>[sn80], const <FontVariation>[w300], 0.9), const <FontVariation>[w300]);
+    expect(lerpFontVariations(const <FontVariation>[sn80], const <FontVariation>[w300], 1.0), const <FontVariation>[w300]);
+    expect(lerpFontVariations(const <FontVariation>[sn40, s0, w100], const <FontVariation>[sp40, w300, sp80], 0.5), anyOf(equals(const <FontVariation>[s0, w200, sp40]), equals(const <FontVariation>[s0, sp40, w200])));
+  });
 }

packages/flutter/test/widgets/icon_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui';
-
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';