fix description for semantics finders (flutter#181214)

navaronbracke · web-flow · commit b4a23495b4ae · 2026-01-21T23:11:00.000Z
Fixes flutter#181196 This PR fixes the description for the bySemanticsLabel/Identifier matchers, which was missing. Note: The framework uses `byElementPredicate()` in a bunch of places in tests, but not all use the `description` field. Should we add descriptions to those? Example: ```dart import 'package:flutter/material.dart'; import 'package:flutter_test/flutter_test.dart'; void main() { testWidgets('bySemanticsLabel', (tester) async { await tester.pumpWidget(const MaterialApp(home: Text('hello'))); await tester.pumpAndSettle(); expect(find.bySemanticsLabel('goodbye'), findsOneWidget); }); testWidgets('bySemanticsLabel regex', (tester) async { await tester.pumpWidget(const MaterialApp(home: Text('hello'))); await tester.pumpAndSettle(); expect(find.bySemanticsLabel(RegExp('^foo')), findsOneWidget); }); testWidgets('bySemanticsIdentifier', (tester) async { await tester.pumpWidget(const MaterialApp(home: Text('hello'))); await tester.pumpAndSettle(); expect(find.bySemanticsIdentifier('goodbye'), findsOneWidget); }); testWidgets('bySemanticsIdentifier regex', (tester) async { await tester.pumpWidget(const MaterialApp(home: Text('hello'))); await tester.pumpAndSettle(); expect(find.bySemanticsIdentifier(RegExp('^foo')), findsOneWidget); }); } ``` now gives: ```dart ══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════ The following TestFailure was thrown running a test: Expected: exactly one matching candidate Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics label named "goodbye": []> Which: means none were found but one was expected When the exception was thrown, this was the stack: #4 main.<anonymous closure> (file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart:8:5) <asynchronous suspension> #5 testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:192:15) <asynchronous suspension> #6 TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:1692:5) <asynchronous suspension> <asynchronous suspension> (elided one frame from package:stack_trace) This was caught by the test expectation on the following line: file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart line 8 The test description was: bySemanticsLabel ════════════════════════════════════════════════════════════════════════════════════════════════════ ══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════ The following TestFailure was thrown running a test: Expected: exactly one matching candidate Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics label matching the pattern "^foo": []> Which: means none were found but one was expected When the exception was thrown, this was the stack: #4 main.<anonymous closure> (file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart:14:5) <asynchronous suspension> #5 testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:192:15) <asynchronous suspension> #6 TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:1692:5) <asynchronous suspension> <asynchronous suspension> (elided one frame from package:stack_trace) This was caught by the test expectation on the following line: file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart line 14 The test description was: bySemanticsLabel regex ════════════════════════════════════════════════════════════════════════════════════════════════════ ══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════ The following TestFailure was thrown running a test: Expected: exactly one matching candidate Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics identifier named "goodbye": []> Which: means none were found but one was expected When the exception was thrown, this was the stack: #4 main.<anonymous closure> (file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart:20:5) <asynchronous suspension> #5 testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:192:15) <asynchronous suspension> #6 TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:1692:5) <asynchronous suspension> <asynchronous suspension> (elided one frame from package:stack_trace) This was caught by the test expectation on the following line: file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart line 20 The test description was: bySemanticsIdentifier ════════════════════════════════════════════════════════════════════════════════════════════════════ ══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════ The following TestFailure was thrown running a test: Expected: exactly one matching candidate Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics identifier matching the pattern "^foo": []> Which: means none were found but one was expected When the exception was thrown, this was the stack: #4 main.<anonymous closure> (file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart:26:5) <asynchronous suspension> #5 testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:192:15) <asynchronous suspension> #6 TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:1692:5) <asynchronous suspension> <asynchronous suspension> (elided one frame from package:stack_trace) This was caught by the test expectation on the following line: file:///Users/navaronbracke/Desktop/matchers_test/test/widget_test.dart line 26 The test description was: bySemanticsIdentifier regex ════════════════════════════════════════════════════════════════════════════════════════════════════ ``` *If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].* ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [ ] All existing and new tests are passing. 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[Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
diff --git a/packages/flutter_test/lib/src/finders.dart b/packages/flutter_test/lib/src/finders.dart
@@ -567,8 +567,15 @@ class CommonFinders {
   /// If the `skipOffstage` argument is true (the default), then this skips
   /// nodes that are [Offstage] or that are from inactive [Route]s.
   Finder bySemanticsLabel(Pattern label, {bool skipOffstage = true}) {
+    final String description = switch (label) {
+      final RegExp regExp => 'a semantics label matching the pattern "${regExp.pattern}"',
+      final String labelString => 'a semantics label named "$labelString"',
+      _ => 'a semantics label matching "$label"',
+    };
+
     return _bySemanticsProperty(
       label,
+      description,
       (SemanticsNode? semantics) => semantics?.label,
       skipOffstage: skipOffstage,
     );
@@ -591,15 +598,23 @@ class CommonFinders {
   /// If the `skipOffstage` argument is true (the default), then this skips
   /// nodes that are [Offstage] or that are from inactive [Route]s.
   Finder bySemanticsIdentifier(Pattern identifier, {bool skipOffstage = true}) {
+    final String description = switch (identifier) {
+      final RegExp regExp => 'a semantics identifier matching the pattern "${regExp.pattern}"',
+      final String id => 'a semantics identifier named "$id"',
+      _ => 'a semantics identifier matching "$identifier"',
+    };
+
     return _bySemanticsProperty(
       identifier,
+      description,
       (SemanticsNode? semantics) => semantics?.identifier,
       skipOffstage: skipOffstage,
     );
   }
 
   Finder _bySemanticsProperty(
     Pattern pattern,
+    String description,
     String? Function(SemanticsNode?) propertyGetter, {
     bool skipOffstage = true,
   }) {
@@ -610,18 +625,23 @@ class CommonFinders {
         'this finder, and call dispose on its return value after.',
       );
     }
-    return byElementPredicate((Element element) {
-      // Multiple elements can have the same renderObject - we want the "owner"
-      // of the renderObject, i.e. the RenderObjectElement.
-      if (element is! RenderObjectElement) {
-        return false;
-      }
-      final String? propertyValue = propertyGetter(element.renderObject.debugSemantics);
-      if (propertyValue == null) {
-        return false;
-      }
-      return pattern is RegExp ? pattern.hasMatch(propertyValue) : pattern == propertyValue;
-    }, skipOffstage: skipOffstage);
+
+    return byElementPredicate(
+      (Element element) {
+        // Multiple elements can have the same renderObject - we want the "owner"
+        // of the renderObject, i.e. the RenderObjectElement.
+        if (element is! RenderObjectElement) {
+          return false;
+        }
+        final String? propertyValue = propertyGetter(element.renderObject.debugSemantics);
+        if (propertyValue == null) {
+          return false;
+        }
+        return pattern is RegExp ? pattern.hasMatch(propertyValue) : pattern == propertyValue;
+      },
+      description: description,
+      skipOffstage: skipOffstage,
+    );
   }
 }
 
diff --git a/packages/flutter_test/test/finders_test.dart b/packages/flutter_test/test/finders_test.dart
@@ -359,6 +359,92 @@ void main() {
       expect(find.bySemanticsIdentifier(RegExp(r'^item-')), findsNWidgets(2));
       semanticsHandle.dispose();
     });
+
+    testWidgets(
+      'bySemanticsIdentifier contains given semantics identifier string in the error message',
+      (WidgetTester tester) async {
+        await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
+
+        late TestFailure failure;
+        try {
+          expect(find.bySemanticsIdentifier('custom-identifier'), findsOneWidget);
+        } on TestFailure catch (e) {
+          failure = e;
+        }
+
+        expect(failure, isNotNull);
+        expect(
+          failure.message,
+          contains(
+            'Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics identifier named "custom-identifier"',
+          ),
+        );
+      },
+    );
+
+    testWidgets(
+      'bySemanticsIdentifier contains given semantics identifier RegExp in the error message',
+      (WidgetTester tester) async {
+        await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
+
+        late TestFailure failure;
+        try {
+          expect(find.bySemanticsIdentifier(RegExp(r'^item-')), findsOneWidget);
+        } on TestFailure catch (e) {
+          failure = e;
+        }
+
+        expect(failure, isNotNull);
+        expect(
+          failure.message,
+          contains(
+            'Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics identifier matching the pattern "^item-"',
+          ),
+        );
+      },
+    );
+
+    testWidgets('bySemanticsLabel contains given label string in the error message', (
+      WidgetTester tester,
+    ) async {
+      await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
+
+      late TestFailure failure;
+      try {
+        expect(find.bySemanticsLabel('label'), findsOneWidget);
+      } on TestFailure catch (e) {
+        failure = e;
+      }
+
+      expect(failure, isNotNull);
+      expect(
+        failure.message,
+        contains(
+          'Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics label named "label"',
+        ),
+      );
+    });
+
+    testWidgets('bySemanticsLabel contains given label RegExp in the error message', (
+      WidgetTester tester,
+    ) async {
+      await tester.pumpWidget(const Text('foo', textDirection: TextDirection.ltr));
+
+      late TestFailure failure;
+      try {
+        expect(find.bySemanticsLabel(RegExp(r'^item-')), findsOneWidget);
+      } on TestFailure catch (e) {
+        failure = e;
+      }
+
+      expect(failure, isNotNull);
+      expect(
+        failure.message,
+        contains(
+          'Actual: _ElementPredicateWidgetFinder:<Found 0 widgets with a semantics label matching the pattern "^item-"',
+        ),
+      );
+    });
   });
 
   group('byTooltip', () {
