# FedCM Testing
`fedcm-mojojs-helper.js` exposes `fedcm_mojo_mock_test` which is a specialized
`promise_test` which comes pre-setup with the appropriate mocking infrastructure
to emulate platform federated auth backend. The mock is passed to the test
function as the second parameter.
Example usage:
```
<script type="module">
import {fedcm_mojo_mock_test} from './support/fedcm-mojojs-helper.js';
fedcm_mojo_mock_test(async (t, mock) => {
mock.returnToken("
https://idp.test/fedcm.json", "a_token");
assert_equals("a_token", await navigator.credentials.get(options));
}, "Successfully obtaining a token using mock.");
</script>
```
The chromium implementation uses the MojoJS shim.
