Mocking at the Wrong Layer: When Your Tests Deceive You

Choosing the correct layer to mock is fundamental to reliable unit testing, yet it's a mistake many developers make. When you mock at the API layer instead of the database layer, your tests create a false sense of confidence—they pass while your actual code fails in production. This pattern is especially dangerous in complex operations like pagination, where subtle mismatches between your mock and reality silently introduce hard-to-catch bugs.