README.md

Testing-related utilities

EUI uses many of the utilities in this directory in its own Jest tests and, in case they are useful for consuming apps, exports them from @elastic/eui/lib/test (commonjs) and @elastic/eui/es/test (esm)

findTestSubject

Provides a quick mechanism for searching an Enzyme-mounted component tree for an element with a specific data-test-subj attribute.

// if mountedComponent contains e.g. <button data-test-subj="custom-button"/>, this would return that button
const component = findTestSubject(mountedComponent, 'custom-button');

startThrowingReactWarnings

Patches console.warn and console.error to throw any warnings or errors, causing Jest to fail the test. This catches warnings emitted by React.

stopThrowingReactWarnings

Must be called after startThrowingReactWarnings, this unpatches the console and restores normal functionality.

sleep

Returns an awaitable promise that resolves after the specified duration.

doSomeAction();
await sleep(500); // wait 500ms
expect(resultOfSomeAction);

takeMountedSnapshot

Use this function to generate a Jest snapshot of components that have been fully rendered using Enzyme's mount method. Typically, a mounted component will result in a snapshot containing both React components and HTML elements. This function removes the React components, leaving only HTML elements in the snapshot.

This function takes an optional configuration as a second argument, which supports one option: hasArrayOutput. Enable this option if the mounted component has multiple direct children, otherwise only the first is included in the snapshot.

expect(
  takeMountedSnapshot(mountedComponent, {
    hasArrayOutput: true,
  })
).toMatchSnapshot();