Good tests give confidence to refactor and ship. Here's how to test React components in a way that's maintainable and catches real bugs.
Testing Philosophy
Test behavior, not implementation:
- What users see and do
- Component outputs
- Side effects
Avoid testing:
- Internal state
- Implementation details
- Things React already tests
Setup
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Basic Component Testing
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Testing User Interactions
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Testing Async Behavior
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Testing Hooks
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Testing Context
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Testing with MSW
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Snapshot Testing
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Best Practices
Queries:
✓ getByRole > getByText > getByTestId
✓ Use accessible queries
✓ Query what users see
✓ Use findBy for async
Structure:
✓ Arrange, Act, Assert
✓ One assertion focus per test
✓ Descriptive test names
✓ Setup common in beforeEach
Avoid:
✗ Testing implementation details
✗ Snapshot testing everything
✗ Testing third-party libraries
✗ Overly complex test setups
Conclusion
Test React components by focusing on user behavior and outcomes. Use Testing Library's queries that encourage accessibility, mock external dependencies with MSW, and avoid testing implementation details. Good tests should survive refactors that don't change behavior.