A Guide to Simplified Mocking in Elixir Tests

In this article, Peter Ullrich addresses the challenge of mocking external dependencies in Elixir tests, sharing a simple, dependency-free alternative. He believes in the importance of comprehensive testing and frequently writes tests, even in their preliminary form, to cover edge cases. Ullrich highlights various existing mocking libraries but introduces a more straightforward method involving the replacement of dependency modules based on the environment configuration. This way, during testing, the real dependencies can easily be swapped with mocks. He demonstrates this method with an example using the Stripe API, illustrating how to configure and implement a mock. The article includes sample tests to validate the mock's functionality and emphasizes the benefits of defining a single mock that can be reused across tests without redundancy. The overall approach aims to streamline testing in Elixir applications.