skill: add dart skills

.agents/skills/dart-add-unit-test/SKILL.md

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+---
+name: dart-add-unit-test
+description: Write and organize unit tests for functions, methods, and classes using `package:test`. Use when creating new logic or fixing bugs to ensure code remains correct and regression-free.
+metadata:
+  model: models/gemini-3.1-pro-preview
+  last_modified: Fri, 24 Apr 2026 15:07:58 GMT
+---
+# Testing Dart and Flutter Applications
+
+## Contents
+- [Structuring Test Files](#structuring-test-files)
+- [Writing Tests](#writing-tests)
+- [Executing Tests](#executing-tests)
+- [Test Implementation Workflow](#test-implementation-workflow)
+- [Examples](#examples)
+
+## Structuring Test Files
+Organize test files to mirror the `lib` directory structure to maintain predictability.
+
+* Place all test code within the `test` directory at the root of the package.
+* Append `_test.dart` to the end of all test file names (e.g., `lib/src/utils.dart` should be tested in `test/src/utils_test.dart`).
+* If writing integration tests, place them in an `integration_test` directory at the root of the package.
+
+## Writing Tests
+Utilize `package:test` as the standard testing library for Dart applications.
+
+* Import `package:test/test.dart` (or `package:flutter_test/flutter_test.dart` for Flutter).
+* Group related tests using the `group()` function to provide shared context.
+* Define individual test cases using the `test()` function.
+* Validate outcomes using the `expect()` function alongside matchers (e.g., `equals()`, `isTrue`, `throwsA()`).
+* Write asynchronous tests using standard `async`/`await` syntax. The test runner automatically waits for the `Future` to complete.
+* Manage test setup and teardown using `setUp()` and `tearDown()` callbacks.
+* If testing code that relies on dependency injection, use `package:mockito` alongside `package:test` to generate mock objects, configure fixed scenarios, and verify interactions.
+
+## Executing Tests
+Select the appropriate test runner based on the project type and test location.
+
+* If working on a pure Dart project, execute tests using the `dart test` command.
+* If working on a Flutter project, execute tests using the `flutter test` command.
+* If running integration tests, explicitly specify the directory path, as the default runner ignores it: `dart test integration_test` or `flutter test integration_test`.
+
+## Test Implementation Workflow
+
+Follow this sequential workflow when implementing new test suites. Copy the checklist to track your progress.
+
+### Task Progress
+- [ ] 1. Create the test file in the `test/` directory, ensuring the `_test.dart` suffix.
+- [ ] 2. Import `package:test/test.dart` and the target library.
+- [ ] 3. Define a `main()` function.
+- [ ] 4. Initialize shared resources or mocks using `setUp()`.
+- [ ] 5. Write `test()` cases grouped by functionality using `group()`.
+- [ ] 6. Execute the test suite using the appropriate CLI command.
+- [ ] 7. **Feedback Loop**: Run test -> Review stack trace for failures -> Fix implementation or assertions -> Re-run until passing.
+
+## Examples
+
+### Standard Unit Test Suite
+Demonstrates grouping, setup, synchronous, and asynchronous testing.
+
+```dart
+import 'package:test/test.dart';
+import 'package:my_package/calculator.dart';
+
+void main() {
+  group('Calculator', () {
+    late Calculator calc;
+
+    setUp(() {
+      calc = Calculator();
+    });
+
+    test('adds two numbers correctly', () {
+      expect(calc.add(2, 3), equals(5));
+    });
+
+    test('handles asynchronous operations', () async {
+      final result = await calc.fetchRemoteValue();
+      expect(result, isNotNull);
+      expect(result, greaterThan(0));
+    });
+  });
+}
+```
+
+### Mocking with Mockito
+Demonstrates configuring a mock object for dependency injection testing.
+
+```dart
+import 'package:test/test.dart';
+import 'package:mockito/mockito.dart';
+import 'package:mockito/annotations.dart';
+import 'package:my_package/api_client.dart';
+import 'package:my_package/data_service.dart';
+
+// Generate the mock using build_runner: dart run build_runner build
+@GenerateNiceMocks([MockSpec<ApiClient>()])
+import 'data_service_test.mocks.dart';
+
+void main() {
+  group('DataService', () {
+    late MockApiClient mockApiClient;
+    late DataService dataService;
+
+    setUp(() {
+      mockApiClient = MockApiClient();
+      dataService = DataService(apiClient: mockApiClient);
+    });
+
+    test('returns parsed data on successful API call', () async {
+      // Configure the mock
+      when(mockApiClient.get('/data')).thenAnswer((_) async => '{"id": 1}');
+
+      // Execute the system under test
+      final result = await dataService.fetchData();
+
+      // Verify outcomes and interactions
+      expect(result.id, equals(1));
+      verify(mockApiClient.get('/data')).called(1);
+    });
+  });
+}
+```