Matchers

toMatchBaseline(options: {threshold?: number} = {threshold: 0.1})

This custom Jest matcher will try to find and compare the baseline screenshot by using the path of the latest screenshot (returned by takeScreenshot()). You will have to take a screenshot before using, and pass the path of that screenshot to the expect method.

Example

__tests__/App.owl.tsx

import { takeScreenshot } from 'react-native-owl';

describe('App.tsx', () => {
  it('takes a screenshot of the first screen', async () => {
    const screen = await takeScreenshot('homescreen');

    expect(screen).toMatchBaseline();

    // Or with a custom threshold
    expect(screen).toMatchBaseline({ threshold: 0.2 });
  });
});

The first time this test is run, or when run with the --update flag, the .toMatchBaseline expectation will always be successful.

On subsequent test runs, the screenshot captured by takeScreenshot (and stored in /current) will be compared to the baseline screenshot. Any differences will cause the expectation to fail, and the report to be generated.

The threshold option allows you to customise the threshold for pixelmatch which Owl uses under the hood.