Extend test fixtures

Use test.extend() when several tests need the same launch and setup. Keep one-off files and options in the test that uses them.

Create an application fixture

import { fileURLToPath } from 'node:url';
import type { TerminalHarness } from 'termwright';
import { expect, test as base } from 'termwright/test';

const editor = fileURLToPath(new URL('../editor.js', import.meta.url));

const test = base.extend<{ app: TerminalHarness }>({
  app: async ({ terminal }, use) => {
    const app = await terminal.launch({
      command: [process.execPath, editor],
      files: { 'config.json': '{}' },
    });
    await app.waitForText('Ready');
    await use(app);
  },
});

test('saves on Ctrl+S', async ({ app }) => {
  await app.press('Control+s');
  await expect(app).toHaveText('Saved');
});

The custom fixture is typed alongside terminal, step, and the other Termwright fixtures. Teardown runs inside-out, so the terminal session remains available while the custom fixture finishes its cleanup.

Apply options to a file or suite

Use test.override() to change launch defaults for a file or nested describe:

import { describe, test } from 'termwright/test';

test.override({ termwrightOptions: { columns: 120, trace: 'on' } });

describe('wide layout', () => {
  test.override({ termwrightOptions: { columns: 200 } });
  // Tests here use 200 columns. Other tests in the file use 120.
});

Suite overrides merge between project configuration and an individual launch:

configureTermwright() < test.override() < terminal.launch()

env and timeouts merge by key. command replaces the complete argv rather than concatenating argument lists. See Configuration for the exact option surface.

Choose where setup belongs

Setup	Recommended location
Files needed by one case	terminal.launch({files}) in that case
Shared project tree	terminal.launch({template})
Reusable launch and login flow	test.extend() fixture
Viewport or trace default for a suite	test.override()
Project-wide default	configureTermwright()

See Test files and isolation for working-directory behavior.