assertion-patterns

Unit tests that rely on mock-based assertions often pass by merely verifying that a function was called, without testing real behavior. Transforming these tests to verify actual observable outcomes ensures your code works outside the mock environment.

To refactor tests for behavior verification, replace mock call assertions with checks against actual observable outcomes. This includes validating real outputs from function calls, process spawns, file operations, HTTP requests, and database interactions.

You should stop mocking the system under test when your tests violate behavior verification principles, such as T1 violations. Refactoring these tests ensures you are validating actual output and meaningful behavior rather than just confirming a function was executed.

Valid unit tests require prerequisite checks, known as T0 checks, to verify production module imports and enforce proper separation of concerns within test files. This prevents tests from "testing nothing real" and ensures meaningful confidence.

Yes, you can test file operations and HTTP requests without mocking by using assertion patterns that verify actual observable behavior. Instead of asserting a mock was called, you validate the real file contents written or the actual HTTP response received.

The best way to fix false positive test suites is to audit them for mock-based assertions and refactor those tests to verify real output. Enforcing prerequisite checks for production module imports ensures tests provide meaningful confidence in actual system behavior.