# Testing Patterns

**Analysis Date:** 2026-04-16

## Framework

**Runner:**
- `flutter_test` (Flutter SDK built-in)
- `integration_test` (Flutter SDK built-in, for E2E/integration tests)
- No explicit `test` package dependency (uses Flutter's bundled test framework)

**Assertion Library:**
- Built-in `flutter_test` matchers (`expect`, `findsOneWidget`, `isEmpty`, `isInstanceOf`)

**Dependencies:**
- `flutter_test` (sdk: flutter) - Unit and widget testing
- `flutter_lints` (^3.0.0) - Code analysis
- `plugin_platform_interface` (^2.0.2) - Required for mock platform interface mixin

**Run Commands:**
```bash
flutter test                          # Run all unit tests
flutter test --coverage              # Run tests with coverage
flutter test test/ch34_test.dart     # Run a specific test file
flutter test integration_test/       # Run integration tests (from example/)
```

## Test Structure

**Test File Organization:**
- Plugin tests in `D:/code/new_git_code/flutter/ch34/test/`:
  - `ch34_test.dart` - Unit tests with mock platform
  - `ch34_method_channel_test.dart` - MethodChannel-level tests with mock handler
- Example app tests in `D:/code/new_git_code/flutter/ch34/example/test/`:
  - `widget_test.dart` - Widget tests for example app
- Integration tests in `D:/code/new_git_code/flutter/ch34/example/integration_test/`:
  - `plugin_integration_test.dart` - End-to-end plugin tests on real device

**Naming:**
- Test files: `{source_file}_test.dart` pattern
- Integration test files: `{feature}_integration_test.dart`

**Test Entry Pattern:**
All tests call framework initialization before running:
```dart
// Unit tests
TestWidgetsFlutterBinding.ensureInitialized();

// Integration tests
IntegrationTestWidgetsFlutterBinding.ensureInitialized();
```

**Suite Organization:**
Unit tests follow a consistent pattern:

```dart
// D:/code/new_git_code/flutter/ch34/test/ch34_test.dart
void main() {
  MethodChannelCh34.registerDefault();
  final Ch34Platform initialPlatform = Ch34Platform.instance;

  test('$MethodChannelCh34 is the default instance', () {
    expect(initialPlatform, isInstanceOf<MethodChannelCh34>());
  });

  test('getPlatformVersion', () async {
    MockCh34Platform fakePlatform = MockCh34Platform();
    Ch34Platform.instance = fakePlatform;

    expect(await Ch34Manager.getPlatformVersion(), '42');
  });

  test('enumDevice returns empty list', () async {
    MockCh34Platform fakePlatform = MockCh34Platform();
    Ch34Platform.instance = fakePlatform;

    final devices = await Ch34Manager.enumDevice();
    expect(devices, isEmpty);
  });
}
```

## Mocking

**Framework:** Manual mock classes (no mockito or mocktail dependency)

**Platform Mock Pattern:**
`D:/code/new_git_code/flutter/ch34/test/ch34_test.dart` uses `MockPlatformInterfaceMixin` for creating test doubles:

```dart
class MockCh34Platform
    with MockPlatformInterfaceMixin
    implements Ch34Platform {

  @override
  Future<String?> getPlatformVersion() => Future.value('42');

  @override
  Future<List<UsbDeviceInfo>> enumDevice() => Future.value([]);

  // ... all 30+ methods must be overridden
}
```

**Mock Usage Pattern:**
Mock instances are swapped into the platform interface before each test:
```dart
MockCh34Platform fakePlatform = MockCh34Platform();
Ch34Platform.instance = fakePlatform;

expect(await Ch34Manager.getPlatformVersion(), '42');
```

**MethodChannel Mock Pattern:**
`D:/code/new_git_code/flutter/ch34/test/ch34_method_channel_test.dart` uses `setMockMethodCallHandler` for low-level channel mocking:

```dart
const MethodChannel channel = MethodChannel('ch34');

setUp(() {
  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(
    channel,
    (MethodCall methodCall) async {
      return '42';  // Returns same value for all method calls
    },
  );
});

tearDown(() {
  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(channel, null);
});
```

**What to Mock:**
- Platform interface layer (`Ch34Platform`) for testing `Ch34Manager` delegation
- `MethodChannel` for testing `MethodChannelCh34` channel mapping

**What NOT to Mock:**
- Native Android code (tested via integration tests on real device)
- EventChannel streams (not currently mocked in any test)

## Coverage

**Requirements:** No coverage target enforced

**Current State:**
- Only 2 unit test assertions beyond boilerplate (`getPlatformVersion`, `enumDevice returns empty list`)
- MethodChannel test has only 1 assertion (`getPlatformVersion`)
- Integration test has 1 assertion (`getPlatformVersion` on real device)
- Most platform methods have zero test coverage (GPIO, serial I/O, modem status, signal control, etc.)

**View Coverage:**
```bash
flutter test --coverage
# Coverage written to coverage/lcov.info
```

## Test Locations

**Unit Tests:**
- `D:/code/new_git_code/flutter/ch34/test/ch34_test.dart` - Ch34Manager + mock platform
- `D:/code/new_git_code/flutter/ch34/test/ch34_method_channel_test.dart` - MethodChannel tests

**Integration Tests:**
- `D:/code/new_git_code/flutter/ch34/example/integration_test/plugin_integration_test.dart` - Real device tests

**Widget Tests:**
- `D:/code/new_git_code/flutter/ch34/example/test/widget_test.dart` - Example app widget test (currently outdated - looks for "Running on:" text that no longer exists)

## Test Types

**Unit Tests:**
- Scope: Test `Ch34Manager` delegation to mocked platform
- Approach: Replace `Ch34Platform.instance` with `MockCh34Platform`
- Current coverage: 2 methods tested out of 30+ API methods

**Integration Tests:**
- Framework: `integration_test` package
- Approach: Run on real Android device with actual USB hardware
- Current coverage: 1 test (`getPlatformVersion`)

**E2E Tests:**
- No dedicated E2E test framework beyond `integration_test`

## Common Patterns

**Async Testing:**
All platform method tests use `async/await`:
```dart
test('enumDevice returns empty list', () async {
  MockCh34Platform fakePlatform = MockCh34Platform();
  Ch34Platform.instance = fakePlatform;

  final devices = await Ch34Manager.enumDevice();
  expect(devices, isEmpty);
});
```

**Error Testing:**
Mock throws exceptions to test error paths:
```dart
@override
Future<GpioStatus> queryGpioStatus(String deviceName, int gpioIndex) =>
    throw const Ch34Exception('Not supported');
```

**Setup/Teardown Pattern:**
```dart
setUp(() {
  // Configure mock method channel handler
  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(channel, handler);
});

tearDown(() {
  // Clean up mock handler
  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(channel, null);
});
```

## CI Testing

**CI Pipeline:** Not detected - no `.github/workflows/`, `.gitlab-ci.yml`, or `azure-pipelines.yml` found.

**Recommendation:** Tests should be run via `flutter analyze && flutter test` in any CI pipeline.

---

*Testing analysis: 2026-04-16*