Add tests for curve2_d.0.dart (flutter#150984)

Contributes to flutter#130459

It adds a test for
- `examples/api/lib/animation/curves/curve2_d.0.dart`

Author: ValentinVignal

dev/bots/check_code_samples.dart

@@ -378,6 +378,5 @@ final Set<String> _knownMissingTests = <String>{
   'examples/api/test/widgets/actions/focusable_action_detector.0_test.dart',
   'examples/api/test/widgets/focus_scope/focus_scope.0_test.dart',
   'examples/api/test/widgets/scroll_view/custom_scroll_view.1_test.dart',
-  'examples/api/test/animation/curves/curve2_d.0_test.dart',
   'examples/api/test/gestures/pointer_signal_resolver/pointer_signal_resolver.0_test.dart',
 };

dev/bots/test/check_code_samples_test.dart

@@ -48,10 +48,6 @@ void main() {
     final File barExample = examplesLib.childFile('bar_example.0.dart')
       ..createSync(recursive: true)
       ..writeAsStringSync('// Example for bar');
-    final File curvesExample =
-        examples.childDirectory('lib').childDirectory('animation').childDirectory('curves').childFile('curve2_d.0.dart')
-          ..createSync(recursive: true)
-          ..writeAsStringSync('// Missing a test, but OK');
     if (missingLinks) {
       examplesLib.childFile('missing_example.0.dart')
         ..createSync(recursive: true)
@@ -77,11 +73,9 @@ void main() {
     if (malformedLinks) {
       writeLink(source: flutterPackage.childDirectory('layer').childFile('foo.dart'), example: fooExample, alternateLink: '*See Code *');
       writeLink(source: flutterPackage.childDirectory('layer').childFile('bar.dart'), example: barExample, alternateLink: ' ** See code examples/api/lib/layer/bar_example.0.dart **');
-      writeLink(source: flutterPackage.childDirectory('animation').childFile('curves.dart'), example: curvesExample, alternateLink: '* see code in examples/api/lib/animation/curves/curve2_d.0.dart *');
     } else {
       writeLink(source: flutterPackage.childDirectory('layer').childFile('foo.dart'), example: fooExample);
       writeLink(source: flutterPackage.childDirectory('layer').childFile('bar.dart'), example: barExample);
-      writeLink(source: flutterPackage.childDirectory('animation').childFile('curves.dart'), example: curvesExample);
     }
   }
 
@@ -144,20 +138,16 @@ void main() {
     final String lines = <String>[
       '╔═╡ERROR #1╞════════════════════════════════════════════════════════════════════',
       '║ The following examples are not linked from any source file API doc comments:',
-      if (!isWindows) '║   examples/api/lib/animation/curves/curve2_d.0.dart',
       if (!isWindows) '║   examples/api/lib/layer/foo_example.0.dart',
       if (!isWindows) '║   examples/api/lib/layer/bar_example.0.dart',
-      if (isWindows) r'║   examples\api\lib\animation\curves\curve2_d.0.dart',
       if (isWindows) r'║   examples\api\lib\layer\foo_example.0.dart',
       if (isWindows) r'║   examples\api\lib\layer\bar_example.0.dart',
       '║ Either link them to a source file API doc comment, or remove them.',
       '╚═══════════════════════════════════════════════════════════════════════════════',
       '╔═╡ERROR #2╞════════════════════════════════════════════════════════════════════',
       '║ The following malformed links were found in API doc comments:',
-      if (!isWindows) '║   /flutter sdk/packages/flutter/lib/src/animation/curves.dart:6: ///* see code in examples/api/lib/animation/curves/curve2_d.0.dart *',
       if (!isWindows) '║   /flutter sdk/packages/flutter/lib/src/layer/foo.dart:6: ///*See Code *',
       if (!isWindows) '║   /flutter sdk/packages/flutter/lib/src/layer/bar.dart:6: /// ** See code examples/api/lib/layer/bar_example.0.dart **',
-      if (isWindows) r'║   C:\flutter sdk\packages\flutter\lib\src\animation\curves.dart:6: ///* see code in examples/api/lib/animation/curves/curve2_d.0.dart *',
       if (isWindows) r'║   C:\flutter sdk\packages\flutter\lib\src\layer\foo.dart:6: ///*See Code *',
       if (isWindows) r'║   C:\flutter sdk\packages\flutter\lib\src\layer\bar.dart:6: /// ** See code examples/api/lib/layer/bar_example.0.dart **',
       '║ Correct the formatting of these links so that they match the exact pattern:',

examples/api/test/animation/curves/curve2_d.0_test.dart

@@ -0,0 +1,40 @@
+// 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/material.dart';
+import 'package:flutter_api_samples/animation/curves/curve2_d.0.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('The buzz widget should move around', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.Curve2DExampleApp(),
+    );
+
+    final Finder textFinder = find.widgetWithText(CircleAvatar, 'B');
+    expect(tester.getCenter(textFinder), const Offset(58, 440));
+
+    const List<Offset> expectedOffsets= <Offset>[
+      Offset(43, 407),
+      Offset(81, 272),
+      Offset(185, 103),
+      Offset(378, 92),
+      Offset(463, 392),
+      Offset(479, 124),
+      Offset(745, 389),
+      Offset(450, 555),
+      Offset(111, 475),
+      Offset(58, 440),
+      Offset(43, 407),
+    ];
+
+    const int steps = 10;
+    for (int i = 0; i <= steps; i++) {
+      await tester.pump(const Duration(seconds: 3) * (1 / steps));
+      final Offset center = tester.getCenter(textFinder);
+      expect(center.dx, moreOrLessEquals(expectedOffsets[i].dx, epsilon: 1));
+      expect(center.dy, moreOrLessEquals(expectedOffsets[i].dy, epsilon: 1));
+    }
+  });
+}