Making OAuth Testable: Rethinking OIDC Clients in JavaScript

The real pain point Most OAuth/OIDC integrations in JavaScript are difficult to test in a meaningful way. Testing usually involves mocking network calls, faking redirects, stubbing token responses, and simulating browser state. The result is that you are not testing OAuth. You are testing your mocks. The typical test for an OIDC login flow looks something like this: intercept the fetch call to the token endpoint, return a hardcoded JSON response, check that the UI updated. You have verified that