Using Mocks Wisely in Elixir Testing

The article by José Valim examines the role of mocks in Elixir testing, highlighting common pitfalls and solutions. The author starts with a tweet emphasizing that mocks/stubs do not eliminate the need for explicit interfaces between components. Valim then provides practical examples and guidelines for using mocks effectively. One solution proposed is to replace dependencies via configuration rather than globally modifying them. The article goes on to detail implementing explicit contracts using Elixir behaviors and concludes with practical tips for balancing unit and integration tests and handling dependencies in tests. Valim also emphasizes the need for explicit contracts to manage complexity and improve code design.