enable lint use_test_throws_matchers (#83943)

analysis_options.yaml

@@ -228,6 +228,7 @@ linter:
     - use_rethrow_when_possible
     # - use_setters_to_change_properties # not yet tested
     # - use_string_buffers # has false positives: https://github.com/dart-lang/sdk/issues/34182
+    - use_test_throws_matchers
     # - use_to_and_as_if_applicable # has false positives, so we prefer to catch this by code-review
     - valid_regexps
     - void_checks

packages/flutter/test/animation/tween_test.dart

@@ -14,22 +14,18 @@ void main() {
       end: Object(),
     );
 
-    FlutterError? error;
+    expect(
-    try {
+      () => objectTween.transform(0.1),
-      objectTween.transform(0.1);
+      throwsA(isA<FlutterError>().having(
-    } on FlutterError catch (err) {
+        (FlutterError error) => error.diagnostics.map((DiagnosticsNode node) => node.toString()),
-      error = err;
+        'diagnostics',
-    }
+        <String>[
-
-    if (error == null) {
-      fail('Expected Tween.transform to throw a FlutterError');
-    }
-
-    expect(error.diagnostics.map((DiagnosticsNode node) => node.toString()), <String>[
           'Cannot lerp between "Instance of \'Object\'" and "Instance of \'Object\'".',
           'The type Object might not fully implement `+`, `-`, and/or `*`. $kApiDocsLink',
           'There may be a dedicated "ObjectTween" for this type, or you may need to create one.',
-    ]);
+        ],
+      )),
+    );
   });
 
   test('throws flutter error when tweening types that do not fully satisfy tween requirements - Color', () {
@@ -38,22 +34,18 @@ void main() {
       end: const Color(0xFFFFFFFF),
     );
 
-    FlutterError? error;
+    expect(
-    try {
+      () => colorTween.transform(0.1),
-      colorTween.transform(0.1);
+      throwsA(isA<FlutterError>().having(
-    } on FlutterError catch (err) {
+        (FlutterError error) => error.diagnostics.map((DiagnosticsNode node) => node.toString()),
-      error = err;
+        'diagnostics',
-    }
+        <String>[
-
-    if (error == null) {
-      fail('Expected Tween.transform to throw a FlutterError');
-    }
-
-    expect(error.diagnostics.map((DiagnosticsNode node) => node.toString()), <String>[
           'Cannot lerp between "Color(0xff000000)" and "Color(0xffffffff)".',
           'The type Color might not fully implement `+`, `-`, and/or `*`. $kApiDocsLink',
           'To lerp colors, consider ColorTween instead.',
-    ]);
+        ],
+      )),
+    );
   });
 
   test('throws flutter error when tweening types that do not fully satisfy tween requirements - Rect', () {
@@ -62,22 +54,18 @@ void main() {
       end: const Rect.fromLTWH(2, 2, 2, 2),
     );
 
-    FlutterError? error;
+    expect(
-    try {
+      () => rectTween.transform(0.1),
-      rectTween.transform(0.1);
+      throwsA(isA<FlutterError>().having(
-    } on FlutterError catch (err) {
+        (FlutterError error) => error.diagnostics.map((DiagnosticsNode node) => node.toString()),
-      error = err;
+        'diagnostics',
-    }
+        <String>[
-
-    if (error == null) {
-      fail('Expected Tween.transform to throw a FlutterError');
-    }
-
-    expect(error.diagnostics.map((DiagnosticsNode node) => node.toString()), <String>[
           'Cannot lerp between "Rect.fromLTRB(0.0, 0.0, 10.0, 10.0)" and "Rect.fromLTRB(2.0, 2.0, 4.0, 4.0)".',
           'The type Rect might not fully implement `+`, `-`, and/or `*`. $kApiDocsLink',
           'To lerp rects, consider RectTween instead.',
-    ]);
+        ],
+      )),
+    );
   });
 
   test('throws flutter error when tweening types that do not fully satisfy tween requirements - int', () {
@@ -86,22 +74,18 @@ void main() {
       end: 1,
     );
 
-    FlutterError? error;
+    expect(
-    try {
+      () => colorTween.transform(0.1),
-      colorTween.transform(0.1);
+      throwsA(isA<FlutterError>().having(
-    } on FlutterError catch (err) {
+        (FlutterError error) => error.diagnostics.map((DiagnosticsNode node) => node.toString()),
-      error = err;
+        'diagnostics',
-    }
+        <String>[
-
-    if (error == null) {
-      fail('Expected Tween.transform to throw a FlutterError');
-    }
-
-    expect(error.diagnostics.map((DiagnosticsNode node) => node.toString()), <String>[
           'Cannot lerp between "0" and "1".',
           'The type int returned a double after multiplication with a double value. $kApiDocsLink',
           'To lerp int values, consider IntTween or StepTween instead.',
-    ]);
+        ],
+      )),
+    );
   });
 
   test('Can chain tweens', () {

packages/flutter/test/material/expansion_tile_test.dart

@@ -371,7 +371,8 @@ void main() {
   });
 
   testWidgets('CrossAxisAlignment.baseline is not allowed', (WidgetTester tester) async {
-    try {
+    expect(
+      () {
         MaterialApp(
           home: Material(
             child: ExpansionTile(
@@ -381,14 +382,12 @@ void main() {
             ),
           ),
         );
-    } on AssertionError catch (error) {
+      },
-      expect(error.toString(), contains(
+      throwsA(isA<AssertionError>().having((AssertionError error) => error.toString(), '.toString()', contains(
         'CrossAxisAlignment.baseline is not supported since the expanded'
         ' children are aligned in a column, not a row. Try to use another constant.',
-      ));
+      ))),
-      return;
+    );
-    }
-    fail('AssertionError was not thrown when expandedCrossAxisAlignment is CrossAxisAlignment.baseline.');
   });
 
   testWidgets('expandedCrossAxisAlignment and expandedAlignment default values', (WidgetTester tester) async {

packages/flutter/test/material/reorderable_list_test.dart

@@ -485,11 +485,10 @@ void main() {
             ),
           ),
         );
-        try {
+        await expectLater(
-          await tester.pumpWidget(boilerplate);
+          () => tester.pumpWidget(boilerplate),
-        } catch (e) {
+          returnsNormally,
-          fail('Expected no error, but got $e');
+        );
-        }
       });
 
       group('Accessibility (a11y/Semantics)', () {

packages/flutter/test/services/platform_channel_test.dart

@@ -128,16 +128,15 @@ void main() {
           ]);
         },
       );
-      try {
+      expect(
-        await channel.invokeMethod<dynamic>('sayHello', 'hello');
+        () => channel.invokeMethod<dynamic>('sayHello', 'hello'),
-        fail('Exception expected');
+        throwsA(
-      } on PlatformException catch (e) {
+          isA<PlatformException>()
-        expect(e.code, equals('bad'));
+            .having((PlatformException e) => e.code, 'code', equals('bad'))
-        expect(e.message, equals('Something happened'));
+            .having((PlatformException e) => e.message, 'message', equals('Something happened'))
-        expect(e.details, equals(<String, dynamic>{'a': 42, 'b': 3.14}));
+            .having((PlatformException e) => e.details, 'details', equals(<String, dynamic>{'a': 42, 'b': 3.14})),
-      } catch (e) {
+        ),
-        fail('PlatformException expected');
+      );
-      }
     });
 
     test('can invoke unimplemented method', () async {
@@ -145,15 +144,16 @@ void main() {
         'ch7',
         (ByteData? message) async => null,
       );
-      try {
+      expect(
-        await channel.invokeMethod<void>('sayHello', 'hello');
+        () => channel.invokeMethod<void>('sayHello', 'hello'),
-        fail('Exception expected');
+        throwsA(
-      } on MissingPluginException catch (e) {
+          isA<MissingPluginException>()
-        expect(e.message, contains('sayHello'));
+            .having((MissingPluginException e) => e.message, 'message', allOf(
-        expect(e.message, contains('ch7'));
+              contains('sayHello'),
-      } catch (e) {
+              contains('ch7'),
-        fail('MissingPluginException expected');
+            )),
-      }
+        ),
+      );
     });
 
     test('can invoke unimplemented method (optional)', () async {
@@ -218,15 +218,14 @@ void main() {
       await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
-      try {
+      expect(
-        jsonMethod.decodeEnvelope(envelope!);
+        () => jsonMethod.decodeEnvelope(envelope!),
-        fail('Exception expected');
+        throwsA(
-      } on PlatformException catch (e) {
+          isA<PlatformException>()
-        expect(e.code, equals('bad'));
+            .having((PlatformException e) => e.code, 'code', equals('bad'))
-        expect(e.message, equals('sayHello failed'));
+            .having((PlatformException e) => e.message, 'message', equals('sayHello failed')),
-      } catch (e) {
+        ),
-        fail('PlatformException expected');
+      );
-      }
     });
 
     test('can handle method call with other error result', () async {
@@ -238,15 +237,14 @@ void main() {
       await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
-      try {
+      expect(
-        jsonMethod.decodeEnvelope(envelope!);
+        () => jsonMethod.decodeEnvelope(envelope!),
-        fail('Exception expected');
+        throwsA(
-      } on PlatformException catch (e) {
+          isA<PlatformException>()
-        expect(e.code, equals('error'));
+            .having((PlatformException e) => e.code, 'code', equals('error'))
-        expect(e.message, equals('Invalid argument(s): bad'));
+            .having((PlatformException e) => e.message, 'message', equals('Invalid argument(s): bad')),
-      } catch (e) {
+        ),
-        fail('PlatformException expected');
+      );
-      }
     });
 
     test('can check the mock handler', () async {

packages/flutter/test/services/raw_keyboard_test.dart

@@ -686,16 +686,20 @@ void main() {
         };
       }
 
-      try {
+      expect(
+        () async {
           await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
             SystemChannels.keyEvent.name,
             SystemChannels.keyEvent.codec.encodeMessage(keyEventMessage),
             (ByteData? data) { },
           );
-        fail('Expected an exception, but did not get one.');
+        },
-      } on AssertionError catch (error) {
+        throwsA(isA<AssertionError>().having(
-        expect(error.toString(), contains('Attempted to send a key down event when no keys are in keysPressed'));
+          (AssertionError error) => error.toString(),
-      }
+          '.toString()',
+          contains('Attempted to send a key down event when no keys are in keysPressed'),
+        )),
+      );
     });
   });
 

packages/flutter/test/widgets/selectable_text_test.dart

@@ -1303,7 +1303,8 @@ void main() {
   });
 
   testWidgets('minLines cannot be greater than maxLines', (WidgetTester tester) async {
-    try {
+    expect(
+      () async {
         await tester.pumpWidget(
           overlay(
             child: SizedBox(
@@ -1316,11 +1317,13 @@ void main() {
             ),
           ),
         );
-    } on AssertionError catch (e) {
+      },
-      expect(e.toString(), contains("minLines can't be greater than maxLines"));
+      throwsA(isA<AssertionError>().having(
-      return;
+        (AssertionError error) => error.toString(),
-    }
+        '.toString()',
-    fail('An assert should be triggered when minLines is greater than maxLines');
+        contains("minLines can't be greater than maxLines"),
+      )),
+    );
   });
 
   testWidgets('Selectable height with minLine', (WidgetTester tester) async {

packages/flutter_tools/test/general.shard/generate_localizations_test.dart

@@ -81,31 +81,25 @@ void main() {
 
   group('Setters', () {
     testWithoutContext('setInputDirectory fails if the directory does not exist', () {
-      try {
+      expect(
-        LocalizationsGenerator.inputDirectoryFromPath(fs, 'lib', fs.directory('bogus'));
+        () => LocalizationsGenerator.inputDirectoryFromPath(fs, 'lib', fs.directory('bogus')),
-      } on L10nException catch (e) {
+        throwsA(isA<L10nException>().having(
-        expect(e.message, contains('Make sure that the correct path was provided'));
+          (L10nException e) => e.message,
-        return;
+          'message',
-      }
+          contains('Make sure that the correct path was provided'),
-
+        )),
-      fail(
-        'LocalizationsGenerator.setInputDirectory should fail if the '
-        'directory does not exist.'
       );
     });
 
     testWithoutContext('setting className fails if input string is empty', () {
       _standardFlutterDirectoryL10nSetup(fs);
-      try {
+      expect(
-        LocalizationsGenerator.classNameFromString('');
+        () => LocalizationsGenerator.classNameFromString(''),
-      } on L10nException catch (e) {
+        throwsA(isA<L10nException>().having(
-        expect(e.message, contains('cannot be empty'));
+          (L10nException e) => e.message,
-        return;
+          'message',
-      }
+          contains('cannot be empty'),
-
+        )),
-      fail(
-        'LocalizationsGenerator.className should fail if the '
-        'input string is null.'
       );
     });
 
@@ -179,8 +173,8 @@ void main() {
         .writeAsStringSync(singleEsMessageArbFileString);
 
       // Project path should be intentionally a directory that does not exist.
-      try {
+      expect(
-        LocalizationsGenerator(
+        () => LocalizationsGenerator(
           fileSystem: fs,
           projectPathString: 'absolute/path/to/flutter_project',
           inputPathString: defaultL10nPathString,
@@ -188,15 +182,12 @@ void main() {
           templateArbFileName: defaultTemplateArbFileName,
           outputFileString: defaultOutputFileString,
           classNameString: defaultClassNameString,
-        );
+        ),
-      } on L10nException catch (e) {
+        throwsA(isA<L10nException>().having(
-        expect(e.message, contains('Directory does not exist'));
+          (L10nException e) => e.message,
-        return;
+          'message',
-      }
+          contains('Directory does not exist'),
-
+        )),
-      fail(
-        'An exception should be thrown when the directory '
-        'specified in projectPathString does not exist.'
       );
     });
 
@@ -206,54 +197,46 @@ void main() {
       });
 
       testWithoutContext('fails on string with spaces', () {
-        try {
+        expect(
-          LocalizationsGenerator.classNameFromString('String with spaces');
+          () => LocalizationsGenerator.classNameFromString('String with spaces'),
-        } on L10nException catch (e) {
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('is not a valid public Dart class name'));
+            (L10nException e) => e.message,
-          return;
+            'message',
-        }
+            contains('is not a valid public Dart class name'),
-        fail(
+          )),
-          'LocalizationsGenerator.className should fail if the '
-          'input string is not a valid Dart class name.'
         );
       });
 
       testWithoutContext('fails on non-alphanumeric symbols', () {
-        try {
+        expect(
-          LocalizationsGenerator.classNameFromString('TestClass@123');
+          () => LocalizationsGenerator.classNameFromString('TestClass@123'),
-        } on L10nException catch (e) {
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('is not a valid public Dart class name'));
+            (L10nException e) => e.message,
-          return;
+            'message',
-        }
+            contains('is not a valid public Dart class name'),
-        fail(
+          )),
-          'LocalizationsGenerator.className should fail if the '
-          'input string is not a valid public Dart class name.'
         );
       });
 
       testWithoutContext('fails on camel-case', () {
-        try {
+        expect(
-          LocalizationsGenerator.classNameFromString('camelCaseClassName');
+          () => LocalizationsGenerator.classNameFromString('camelCaseClassName'),
-        } on L10nException catch (e) {
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('is not a valid public Dart class name'));
+            (L10nException e) => e.message,
-          return;
+            'message',
-        }
+            contains('is not a valid public Dart class name'),
-        fail(
+          )),
-          'LocalizationsGenerator.className should fail if the '
-          'input string is not a valid public Dart class name.'
         );
       });
 
       testWithoutContext('fails when starting with a number', () {
-        try {
+        expect(
-          LocalizationsGenerator.classNameFromString('123ClassName');
+          () => LocalizationsGenerator.classNameFromString('123ClassName'),
-        } on L10nException catch (e) {
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('is not a valid public Dart class name'));
+            (L10nException e) => e.message,
-          return;
+            'message',
-        }
+            contains('is not a valid public Dart class name'),
-        fail(
+          )),
-          'LocalizationsGenerator.className should fail if the '
-          'input string is not a valid public Dart class name.'
         );
       });
     });
@@ -339,7 +322,8 @@ void main() {
       .writeAsStringSync(singleMessageArbFileString);
     l10nDirectory.childFile('app_localizations_en_CA_foo.arb')
       .writeAsStringSync(singleMessageArbFileString);
-    try {
+    expect(
+      () {
         LocalizationsGenerator(
           fileSystem: fs,
           inputPathString: defaultL10nPathString,
@@ -347,12 +331,13 @@ void main() {
           outputFileString: defaultOutputFileString,
           classNameString: defaultClassNameString,
         ).loadResources();
-    } on L10nException catch (e) {
+      },
-      expect(e.message, contains("The following .arb file's locale could not be determined"));
+      throwsA(isA<L10nException>().having(
-      return;
+        (L10nException e) => e.message,
-    }
+        'message',
-
+        contains("The following .arb file's locale could not be determined"),
-    fail('Using app_en_CA_foo.arb should fail as it is not a valid locale.');
+      )),
+    );
   });
 
   testWithoutContext('correctly creates an untranslated messages file (useSyntheticPackage = true)', () {
@@ -775,7 +760,8 @@ void main() {
       ..childFile(esArbFileName).writeAsStringSync(singleEsMessageArbFileString)
       ..childFile('header.txt').writeAsStringSync('/// Sample header in a text file');
 
-    try {
+    expect(
+      () {
         LocalizationsGenerator(
           fileSystem: fs,
           inputPathString: defaultL10nPathString,
@@ -786,12 +772,13 @@ void main() {
           headerString: '/// Sample header for localizations file.',
           headerFile: 'header.txt',
         );
-    } on L10nException catch (e) {
+      },
-      expect(e.message, contains('Cannot accept both header and header file arguments'));
+      throwsA(isA<L10nException>().having(
-      return;
+        (L10nException e) => e.message,
-    }
+        'message',
-
+        contains('Cannot accept both header and header file arguments'),
-    fail('Setting both headerFile and headerString should fail');
+      )),
+    );
   });
 
   testWithoutContext('setting a headerFile that does not exist should fail', () {
@@ -804,7 +791,8 @@ void main() {
     l10nDirectory.childFile('header.txt')
       .writeAsStringSync('/// Sample header in a text file');
 
-    try {
+    expect(
+      () {
         LocalizationsGenerator(
           fileSystem: fs,
           inputPathString: defaultL10nPathString,
@@ -814,12 +802,13 @@ void main() {
           classNameString: defaultClassNameString,
           headerFile: 'header.tx', // Intentionally spelled incorrectly
         );
-    } on L10nException catch (e) {
+      },
-      expect(e.message, contains('Failed to read header file'));
+      throwsA(isA<L10nException>().having(
-      return;
+        (L10nException e) => e.message,
-    }
+        'message',
-
+        contains('Failed to read header file'),
-    fail('Setting headerFile that does not exist should fail');
+      )),
+    );
   });
 
   group('generateLocalizations', () {
@@ -1022,7 +1011,8 @@ flutter:
           .writeAsStringSync(singleZhMessageArbFileString);
 
         const List<String> preferredSupportedLocale = <String>['am', 'es'];
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1032,17 +1022,12 @@ flutter:
               classNameString: defaultClassNameString,
               preferredSupportedLocales: preferredSupportedLocale,
             ).loadResources();
-        } on L10nException catch (e) {
+          },
-          expect(
+          throwsA(isA<L10nException>().having(
-            e.message,
+            (L10nException e) => e.message,
+            'message',
             contains("The preferred supported locale, 'am', cannot be added."),
-          );
+          )),
-          return;
-        }
-
-        fail(
-          'Should fail since an unsupported locale was added '
-          'to the preferredSupportedLocales list.'
         );
       },
     );
@@ -1149,25 +1134,22 @@ flutter:
       l10nDirectory.childFile('app_am.arb')
         .writeAsStringSync(arbFileWithZhLocale);
 
-      LocalizationsGenerator generator;
+      expect(
-      try {
+        () {
-        generator = LocalizationsGenerator(
+          LocalizationsGenerator(
             fileSystem: fs,
             inputPathString: defaultL10nPathString,
             outputPathString: defaultL10nPathString,
             templateArbFileName: 'app_es.arb',
             outputFileString: defaultOutputFileString,
             classNameString: defaultClassNameString,
-        );
+          ).loadResources();
-        generator.loadResources();
+        },
-      } on L10nException catch (e) {
+        throwsA(isA<L10nException>().having(
-        expect(e.message, contains('The locale specified in @@locale and the arb filename do not match.'));
+          (L10nException e) => e.message,
-        return;
+          'message',
-      }
+          contains('The locale specified in @@locale and the arb filename do not match.'),
-
+        )),
-      fail(
-        'An exception should occur if the @@locale and the filename extensions are '
-        'defined but not matching.'
       );
     });
 
@@ -1176,23 +1158,22 @@ flutter:
         ..createSync(recursive: true)
         ..childFile('app.arb')
         .writeAsStringSync(singleMessageArbFileString);
-      try {
+      expect(
-        final LocalizationsGenerator generator = LocalizationsGenerator(
+        () {
+          LocalizationsGenerator(
             fileSystem: fs,
             inputPathString: defaultL10nPathString,
             outputPathString: defaultL10nPathString,
             templateArbFileName: 'app.arb',
             outputFileString: defaultOutputFileString,
             classNameString: defaultClassNameString,
-        );
+          ).loadResources();
-        generator.loadResources();
+        },
-      } on L10nException catch (e) {
+        throwsA(isA<L10nException>().having(
-        expect(e.message, contains('locale could not be determined'));
+          (L10nException e) => e.message,
-        return;
+          'message',
-      }
+          contains('locale could not be determined'),
-      fail(
+        )),
-        'Since locale is not specified, setting languages and locales '
-        'should fail'
       );
     });
     testWithoutContext('throws when the same locale is detected more than once', () {
@@ -1211,7 +1192,8 @@ flutter:
       l10nDirectory.childFile('app2_en.arb')
         .writeAsStringSync(secondMessageArbFileString);
 
-      try {
+      expect(
+        () {
           LocalizationsGenerator(
             fileSystem: fs,
             inputPathString: defaultL10nPathString,
@@ -1220,14 +1202,12 @@ flutter:
             outputFileString: defaultOutputFileString,
             classNameString: defaultClassNameString,
           ).loadResources();
-      } on L10nException catch (e) {
+        },
-        expect(e.message, contains("Multiple arb files with the same 'en' locale detected"));
+        throwsA(isA<L10nException>().having(
-        return;
+          (L10nException e) => e.message,
-      }
+          'message',
-
+          contains("Multiple arb files with the same 'en' locale detected"),
-      fail(
+        )),
-        'Since en locale is specified twice, setting languages and locales '
-        'should fail'
       );
     });
 
@@ -1237,7 +1217,8 @@ flutter:
       l10nDirectory.childFile('app_en_US.arb')
         .writeAsStringSync(singleMessageArbFileString);
 
-      try {
+      expect(
+        () {
           LocalizationsGenerator(
             fileSystem: fs,
             inputPathString: defaultL10nPathString,
@@ -1246,14 +1227,12 @@ flutter:
             outputFileString: defaultOutputFileString,
             classNameString: defaultClassNameString,
           ).loadResources();
-      } on L10nException catch (e) {
+        },
-        expect(e.message, contains('Arb file for a fallback, en, does not exist'));
+        throwsA(isA<L10nException>().having(
-        return;
+          (L10nException e) => e.message,
-      }
+          'message',
-
+          contains('Arb file for a fallback, en, does not exist'),
-      fail(
+        )),
-        'Since en_US.arb is specified, but en.arb is not, '
-        'the tool should throw an error.'
       );
     });
   });
@@ -1544,7 +1523,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(singleDateMessageArbFileString);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1554,14 +1534,17 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('asdf'));
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('springStartDate'));
+            (L10nException e) => e.message,
-          expect(e.message, contains('does not have a corresponding DateFormat'));
+            'message',
-          return;
+            allOf(
-        }
+              contains('asdf'),
-
+              contains('springStartDate'),
-        fail('Improper date formatting should throw an exception');
+              contains('does not have a corresponding DateFormat'),
+            ),
+          )),
+        );
       });
 
       testWithoutContext('throws an exception when no format attribute is passed in', () {
@@ -1582,7 +1565,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(singleDateMessageArbFileString);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1593,12 +1577,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('the "format" attribute needs to be set'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-
+            contains('the "format" attribute needs to be set'),
-        fail('Improper date formatting should throw an exception');
+          )),
+        );
       });
     });
 
@@ -1658,7 +1643,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(singleDateMessageArbFileString);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1669,14 +1655,17 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('asdf'));
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('progress'));
+            (L10nException e) => e.message,
-          expect(e.message, contains('does not have a corresponding NumberFormat'));
+            'message',
-          return;
+            allOf(
-        }
+              contains('asdf'),
-
+              contains('progress'),
-        fail('Improper date formatting should throw an exception');
+              contains('does not have a corresponding NumberFormat'),
+            ),
+          )),
+        );
       });
     });
 
@@ -1695,7 +1684,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(pluralMessageWithoutPlaceholdersAttribute);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1706,11 +1696,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Check to see if the plural message is in the proper ICU syntax format'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-        fail('Generating class methods without placeholders should not succeed');
+            contains('Check to see if the plural message is in the proper ICU syntax format'),
+          )),
+        );
       });
 
       testWithoutContext('should throw attempting to generate a plural message with an empty placeholders map', () {
@@ -1728,7 +1720,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(pluralMessageWithEmptyPlaceholdersMap);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1739,11 +1732,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Check to see if the plural message is in the proper ICU syntax format'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-        fail('Generating class methods without placeholders should not succeed');
+            contains('Check to see if the plural message is in the proper ICU syntax format'),
+          )),
+        );
       });
 
       testWithoutContext('should throw attempting to generate a plural message with no resource attributes', () {
@@ -1757,7 +1752,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(pluralMessageWithoutResourceAttributes);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1768,11 +1764,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Resource attribute "@helloWorlds" was not found'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-        fail('Generating plural class method without resource attributes should not succeed');
+            contains('Resource attribute "@helloWorlds" was not found'),
+          )),
+        );
       });
 
       testWithoutContext('should throw attempting to generate a plural message with incorrect format for placeholders', () {
@@ -1789,7 +1787,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(pluralMessageWithIncorrectPlaceholderFormat);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -1800,12 +1799,16 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('is not properly formatted'));
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('Ensure that it is a map with string valued keys'));
+            (L10nException e) => e.message,
-          return;
+            'message',
-        }
+            allOf(
-        fail('Generating class methods with incorrect placeholder format should not succeed');
+              contains('is not properly formatted'),
+              contains('Ensure that it is a map with string valued keys'),
+            ),
+          )),
+        );
       });
     });
 
@@ -2190,7 +2193,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(arbFileWithTrailingComma);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -2201,16 +2205,16 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('app_en.arb'));
+          throwsA(isA<L10nException>().having(
-          expect(e.message, contains('FormatException'));
+            (L10nException e) => e.message,
-          expect(e.message, contains('Unexpected character'));
+            'message',
-          return;
+            allOf(
-        }
+              contains('app_en.arb'),
-
+              contains('FormatException'),
-        fail(
+              contains('Unexpected character'),
-          'should fail with an L10nException due to a trailing comma in the '
+            ),
-          'arb file.'
+          )),
         );
       },
     );
@@ -2225,7 +2229,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
       l10nDirectory.childFile(defaultTemplateArbFileName)
         .writeAsStringSync(arbFileWithMissingResourceAttribute);
 
-      try {
+      expect(
+        () {
           LocalizationsGenerator(
             fileSystem: fs,
             inputPathString: defaultL10nPathString,
@@ -2237,14 +2242,12 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
           )
             ..loadResources()
             ..writeOutputFiles(BufferLogger.test());
-      } on L10nException catch (e) {
+        },
-        expect(e.message, contains('Resource attribute "@title" was not found'));
+        throwsA(isA<L10nException>().having(
-        return;
+          (L10nException e) => e.message,
-      }
+          'message',
-
+          contains('Resource attribute "@title" was not found'),
-      fail(
+        )),
-        'should fail with a FormatException due to a trailing comma in the '
-        'arb file.'
       );
     });
 
@@ -2262,7 +2265,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(nonAlphaNumericArbFile);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -2273,12 +2277,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Invalid ARB resource name'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-
+            contains('Invalid ARB resource name'),
-        fail('should fail due to non-alphanumeric character.');
+          )),
+        );
       });
 
       testWithoutContext('must start with lowercase character', () {
@@ -2294,7 +2299,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(nonAlphaNumericArbFile);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -2305,12 +2311,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Invalid ARB resource name'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-
+            contains('Invalid ARB resource name'),
-        fail('should fail since key starts with a non-lowercase.');
+          )),
+        );
       });
 
       testWithoutContext('cannot start with a number', () {
@@ -2326,7 +2333,8 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
         l10nDirectory.childFile(defaultTemplateArbFileName)
           .writeAsStringSync(nonAlphaNumericArbFile);
 
-        try {
+        expect(
+          () {
             LocalizationsGenerator(
               fileSystem: fs,
               inputPathString: defaultL10nPathString,
@@ -2336,12 +2344,13 @@ import 'output-localization-file_en.dart' deferred as output-localization-file_e
             )
               ..loadResources()
               ..writeOutputFiles(BufferLogger.test());
-        } on L10nException catch (e) {
+          },
-          expect(e.message, contains('Invalid ARB resource name'));
+          throwsA(isA<L10nException>().having(
-          return;
+            (L10nException e) => e.message,
-        }
+            'message',
-
+            contains('Invalid ARB resource name'),
-        fail('should fail since key starts with a number.');
+          )),
+        );
       });
     });
   });