Test Doubles vs Integration Tests

Developers should use test doubles when writing unit tests to isolate code from external dependencies, making tests faster and more deterministic by avoiding network calls, database access, or unpredictable behavior meets developers should use integration tests when building complex applications with multiple interacting parts, such as microservices architectures, apis with external dependencies, or database-driven systems. Here's our take.

Test Doubles

Nice Pick

Developers should use test doubles when writing unit tests to isolate code from external dependencies, making tests faster and more deterministic by avoiding network calls, database access, or unpredictable behavior

Pros

• They are essential in test-driven development (TDD) and continuous integration pipelines to ensure code quality without relying on real infrastructure, such as when testing a payment service without hitting actual payment gateways
• Related to: unit-testing, test-driven-development

Cons

• Specific tradeoffs depend on your use case

Integration Tests

Developers should use integration tests when building complex applications with multiple interacting parts, such as microservices architectures, APIs with external dependencies, or database-driven systems

Pros

• They are crucial for catching bugs that arise from component interactions, such as data format mismatches, communication failures, or state inconsistencies, which unit tests alone might miss
• Related to: unit-testing, end-to-end-testing

Cons

• Specific tradeoffs depend on your use case

The Verdict

These tools serve different purposes. Test Doubles is a concept while Integration Tests is a methodology. We picked Test Doubles based on overall popularity, but your choice depends on what you're building.

The Bottom Line

Test Doubles wins

Based on overall popularity. Test Doubles is more widely used, but Integration Tests excels in its own space.