go-testing

## When to Use Use this skill when: - Writing Go unit tests - Testing Bubbletea TUI components - Creating table-driven tests - Adding integration tests - Using golden file testing --- ## Critical Patterns ### Pattern 1: Table-Driven Tests Standard Go pattern for multiple test cases: ```go func TestSomething(t *testing.T) { tests := []struct { name string input string expected string wantErr bool }{ { name: "valid input", input: "hello", expected: "HELLO", wantErr: false, }, { name: "empty input", input: "", expected: "", wantErr: true, }, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { result, err := ProcessInput(tt.input) if (err != nil) != tt.wantErr { t.Errorf("error = %v, wantErr %v", err, tt.wantErr) return } if result != tt.expected { t.Errorf("got %q, want %q", result, tt.expected) } }) } } ``` ### Pattern 2: Bubbletea Model Testing Test Model state transitions directly: ```go func TestModelUpdate(t *testing.T) { m := NewModel() // Simulate key press newModel, _ := m.Update(tea.KeyMsg{Type: tea.KeyEnter}) m = newModel.(Model) if m.Screen != ScreenMainMenu { t.Errorf("expected ScreenMainMenu, got %v", m.Screen) } } ``` ### Pattern 3: Teatest Integration Tests Use Charmbracelet's teatest for TUI testing: ```go func TestInteractiveFlow(t *testing.T) { m := NewModel() tm := teatest.NewTestModel(t, m) // Send keys tm.Send(tea.KeyMsg{Type: tea.KeyEnter}) tm.Send(tea.KeyMsg{Type: tea.KeyDown}) tm.Send(tea.KeyMsg{Type: tea.KeyEnter}) // Wait for model to update tm.WaitFinished(t, teatest.WithDuration(time.Second)) // Get final model finalModel := tm.FinalModel(t).(Model) if finalModel.Screen != ExpectedScreen { t.Errorf("wrong screen: got %v", finalModel.Screen) } } ``` ### Pattern 4: Golden File Testing Compare output against saved "golden" files: ```go func TestOSSelectGolden(t *testing.T) { m := NewModel() m.Screen = ScreenOSSelect m.Width = 80 m.Height = 24 output := m.View() golden := filepath.Join("testdata", "TestOSSelectGolden.golden") if *update { os.WriteFile(golden, []byte(output), 0644) } expected, _ := os.ReadFile(golden) if output != string(expected) { t.Errorf("output doesn't match golden file") } } ``` --- ## Decision Tree ``` Testing a function? ├── Pure function? → Table-driven test ├── Has side effects? → Mock dependencies ├── Returns error? → Test both success and error cases └── Complex logic? → Break into smaller testable units Testing TUI component? ├── State change? → Test Model.Update() directly ├── Full flow? → Use teatest.NewTestModel() ├── Visual output? → Use golden file testing └── Key handling? → Send tea.KeyMsg Testing system/exec? ├── Mock os/exec? → Use interface + mock ├── Real commands? → Integration test with --short skip └── File operations? → Use t.TempDir() ``` --- ## Code Examples ### Example 1: Testing Key Navigation ```go func TestCursorNavigation(t *testing.T) { tests := []struct { name string startPos int key string endPos int numOptions int }{ {"down from 0", 0, "j", 1, 5}, {"up from 1", 1, "k", 0, 5}, {"down at bottom", 4, "j", 4, 5}, // stays at bottom {"up at top", 0, "k", 0, 5}, // stays at top } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { m := NewModel() m.Cursor = tt.startPos // Set up options... newModel, _ := m.Update(tea.KeyMsg{ Type: tea.KeyRunes, Runes: []rune(tt.key), }) m = newModel.(Model) if m.Cursor != tt.endPos { t.Errorf("cursor = %d, want %d", m.Cursor, tt.endPos) } }) } } ``` ### Example 2: Testing Screen Transitions ```go func TestScreenTransitions(t *testing.T) { tests := []struct { name string startScreen Screen action tea.Msg expectScreen Screen }{ { name: "welcome to main menu", startScreen: ScreenWelcome, action: tea.KeyMsg{Type: tea.KeyEnter}, expectScreen: ScreenMainMenu, }, { name: "escape from OS select", startScreen: ScreenOSSelect, action: tea.KeyMsg{Type: tea.KeyEsc}, expectScreen: ScreenMainMenu, }, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { m := NewModel() m.Screen = tt.startScreen newModel, _ := m.Update(tt.action) m = newModel.(Model) if m.Screen != tt.expectScreen { t.Errorf("screen = %v, want %v", m.Screen, tt.expectScreen) } }) } } ``` ### Example 3: Testing Trainer Exercises ```go func TestExerciseValidation(t *testing.T) { exercise := &Exercise{ Solutions: []string{"w", "W", "e"}, Optimal: "w", } tests := []struct { input string valid bool optimal bool }{ {"w", true, true}, {"W", true, false}, {"e", true, false}, {"x", false, false}, } for _, tt := range tests { t.Run(tt.input, func(t *testing.T) { valid := ValidateAnswer(exercise, tt.input) optimal := IsOptimalAnswer(exercise, tt.input) if valid != tt.valid { t.Errorf("valid = %v, want %v", valid, tt.valid) } if optimal != tt.optimal { t.Errorf("optimal = %v, want %v", optimal, tt.optimal) } }) } } ``` ### Example 4: Mocking System Info ```go func TestWithMockedSystem(t *testing.T) { m := NewModel() // Mock system info for testing m.SystemInfo = &system.SystemInfo{ OS: system.OSMac, IsARM: true, HasBrew: true, HomeDir: t.TempDir(), } // Now test with controlled environment m.SetupInstallSteps() // Verify expected steps hasHomebrew := false for _, step := range m.Steps { if step.ID == "homebrew" { hasHomebrew = true } } if hasHomebrew { t.Error("should not have homebrew step when HasBrew=true") } } ``` --- ## Test File Organization ``` installer/internal/tui/ ├── model.go ├── model_test.go # Model tests ├── update.go ├── update_test.go # Update handler tests ├── view.go ├── view_test.go # View rendering tests ├── teatest_test.go # Teatest integration tests ├── comprehensive_test.go # Full flow tests ├── testdata/ │ ├── TestOSSelectGolden.golden │ └── TestViewGolden.golden └── trainer/ ├── types.go ├── types_test.go ├── exercises.go ├── exercises_test.go └── simulator_test.go ``` --- ## Commands ```bash go test ./... # Run all tests go test -v ./internal/tui/... # Verbose TUI tests go test -run TestNavigation # Run specific test go test -cover ./... # With coverage go test -update ./... # Update golden files go test -short ./... # Skip integration tests ``` --- ## Resources - **TUI Tests**: See `installer/internal/tui/*_test.go` - **Trainer Tests**: See `installer/internal/tui/trainer/*_test.go` - **System Tests**: See `installer/internal/system/*_test.go` - **Golden Files**: See `installer/internal/tui/testdata/` - **Teatest Docs**: https://github.com/charmbracelet/bubbletea/tree/master/teatest