Test Logic in Production

Production code contains testing hooks.

Meszaros, xUnit Test Patterns

Signs of Use (Symptoms)

• if (process.env.TESTING) { ... } in production code.
• Code paths that only exist for tests.

Why it is bad (Consequences)

• Complexity: Production code is cluttered.
• Risk: Testing code might accidentally run in production.

Refactoring Solution

• Dependency Injection: Inject test doubles instead of conditionals.
• Separate test harness from production code.

Code example

Bad

Good