Struct HeadlessTerm 

pub struct HeadlessTerm { /* private fields */ }

A headless terminal for testing without real terminal I/O.

Processes ANSI escape sequences through TerminalModel and provides assertion helpers, snapshot comparison, and export capabilities.

Implementations

impl HeadlessTerm

pub fn new(width: u16, height: u16) -> Self

Create a new headless terminal with the given dimensions.

Panics

Panics if width or height is 0.

pub fn width(&self) -> u16

Terminal width in columns.

pub fn height(&self) -> u16

Terminal height in rows.

pub fn cursor(&self) -> (u16, u16)

Current cursor position as (column, row), 0-indexed.

pub fn process(&mut self, bytes: &[u8])

Process raw bytes through the terminal emulator.

Bytes are parsed as ANSI escape sequences and applied to the internal grid, just as a real terminal would.

pub fn row_text(&self, row: usize) -> String

Get the text content of a single row, trimmed of trailing spaces.

Returns an empty string for out-of-bounds rows.

pub fn screen_text(&self) -> Vec<String>

Get all rows as text, trimmed of trailing spaces.

pub fn screen_string(&self) -> String

Get all rows as a single string joined by newlines.

pub fn model(&self) -> &TerminalModel

Access the underlying TerminalModel for advanced queries.

pub fn captured_output(&self) -> &[u8]

Access all captured output bytes (everything passed to process).

pub fn reset(&mut self)

Reset the terminal to its initial state (blank screen, cursor at origin).

pub fn assert_matches(&self, expected: &[&str])

Assert that the screen content matches the expected lines exactly.

Trailing spaces in both actual and expected lines are trimmed before comparison. The number of expected lines must match the terminal height.

Panics

Panics with a human-readable diff if the content doesn’t match.

pub fn assert_row(&self, row: usize, expected: &str)

Assert that a specific row matches the expected text.

Trailing spaces are trimmed before comparison.

Panics

Panics if the row content doesn’t match.

pub fn assert_cursor(&self, col: u16, row: u16)

Assert that the cursor is at the expected position (column, row), 0-indexed.

Panics

Panics if the cursor position doesn’t match.

pub fn diff(&self, expected: &[&str]) -> Option<ScreenDiff>

Compare screen content with expected lines and return the diff.

Returns None if the content matches exactly.

pub fn export(&self, path: &Path) -> Result<()>

Export the screen content to a file for debugging.

Writes a human-readable text representation including:

• Terminal dimensions
• Cursor position
• Screen content (with line numbers)
• Captured output size

pub fn export_string(&self) -> String

Export the screen content as a formatted string (for inline debugging).

Trait Implementations

impl Debug for HeadlessTerm

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.