A proper fix is already landed for this in jest. It will go out with the next version of jest, so this module is only a temporary solution. See more on the pull request.
A very unlucky interaction between jest and unexpected was found by @sunesimonsen.
When using unexpected it's common to import it under the name expect. Consider this case:
import expect from 'unexpected';
it('should be unexpected', () => {
expect(true, 'to be false');
});If a user by accident forgets to import unexpected, they will not immediately notice, as the builtin expect in jest will ignore any further arguments passed to it. Which will result in a passing test instead of the failure you would expect.
Until jest is released in a version containing this fix, it is available here as a module. It is less optimal, as it only works when you are aware of it, but at least it can help make sure that you don't get burned at all, or at least one time at most.
Install it with npm:
npm install unexpected-jest-fix
Configure jest to use the module as a setupTestFrameworkScriptFile, in your
package.json:
{
"name": "my-package",
"jest": {
"setupTestFrameworkScriptFile": "unexpected-jest-fix"
}
}