Test Helper Reference

Overview

The test helpers use the functional options pattern to make test setup flexible and composable.

Basic Usage

// Default model (6 lines, cursor at 0,0, terminal 80x24)
tm := newTestModel(t)

// With custom lines
tm := newTestModel(t,
    WithLines([]string{"hello", "world"}),
)

// With custom cursor position
tm := newTestModel(t,
    WithCursorPos(action.Position{Line: 1, Col: 5}),
)

// With custom terminal size
tm := newTestModel(t,
    WithTermSize(120, 40),
)

// With register content (useful for paste tests)
tm := newTestModel(t,
    WithRegister('"', action.CharwiseRegister, []string{"yanked text"}),
)

Combining Options

You can combine multiple options in a single call:

tm := newTestModel(t,
    WithLines([]string{"line 1", "line 2", "line 3"}),
    WithCursorPos(action.Position{Line: 1, Col: 0}),
    WithTermSize(100, 30),
    WithRegister('"', action.LinewiseRegister, []string{"deleted line"}),
)

Available Options

Option	Parameters	Description
`WithLines`	`[]string`	Set buffer lines
`WithCursorPos`	`action.Position`	Set cursor position
`WithTermSize`	`width, height int`	Set terminal dimensions
`WithRegister`	`name rune, type RegisterType, content []string`	Set register content

Backward Compatibility

The old helper functions still work for existing tests:

newTestModelWithLines(t, []string{"a", "b"})
newTestModelWithCursorPos(t, action.Position{Line: 1, Col: 2})
newTestModelWithLinesAndCursorPos(t, lines, pos)
newTestModelWithTermSize(t, lines, pos, width, height)

Example Test

func TestPasteCharwise(t *testing.T) {
    tm := newTestModel(t,
        WithLines([]string{"hello world"}),
        WithCursorPos(action.Position{Line: 0, Col: 5}),
        WithRegister('"', action.CharwiseRegister, []string{"PASTE"}),
    )
    
    sendKeys(tm, "p")
    m := getFinalModel(t, tm)
    
    // Assert expected behavior
    if m.Line(0) != "hello PASTEworld" {
        t.Errorf("unexpected result: %s", m.Line(0))
    }
}

Default Values

When options are not specified:

Lines: []string{"line 1", "line 2", "line 3", "line 4", "line 5", "line 6"}
Cursor: {Line: 0, Col: 0}
Terminal: 80x24
Register: None set

Adding New Options

To add a new option:

Add field to testModelConfig
Create a With* function that returns TestModelOption
Apply the option in newTestModel after creating the model

Example:

// In testModelConfig
type testModelConfig struct {
    // ... existing fields
    scrollY int
}

// New option function
func WithScrollY(y int) TestModelOption {
    return func(c *testModelConfig) {
        c.scrollY = y
    }
}

// Apply in newTestModel
if cfg.scrollY > 0 {
    m.SetScrollY(cfg.scrollY)
}

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