go-testing-practices

Description

This rule ensures that Go tests follow best practices for effective, maintainable, and idiomatic testing in Go projects.

Rule

When writing tests in Go:

Test Organization

1. Use table-driven tests for testing multiple scenarios
2. Name test functions as Test<FunctionName> or Test<FunctionName>_<Scenario>
3. Use subtests with t.Run() to organize related test cases
4. Group tests logically by functionality
5. Keep test files in the same package as the code they test

Test Structure

1. Follow the Arrange-Act-Assert (AAA) pattern:
   • Arrange: Set up test data and preconditions
   • Act: Call the function/method being tested
   • Assert: Verify the results
2. Use clear separation between these sections
3. Minimize test setup code; use helper functions for common setup
4. Make test failures descriptive and actionable

Assertions

1. Use t.Errorf() or t.Fatalf() with descriptive messages
2. Include expected vs. actual values in failure messages
3. Avoid testify or similar packages, but do use go-cmp.
4. Prefer t.Fatalf() only when continuing the test is impossible

Mocking and Test Doubles

1. Use interfaces to enable mocking of dependencies
2. Create simple, focused test doubles (mocks, stubs, fakes)
3. Consider using the standard library's httptest for HTTP testing
4. Avoid sqlmock or similar tools for database testing, stick to the stdlib

Test Coverage

1. High test coverage is not a goal in and of itself, focus on critical code paths
2. Test edge cases and error conditions
3. Use go test -cover to measure coverage
4. Use go test -race to detect race conditions

Implementation

• The Cursor IDE will enforce this rule by:
  • Suggesting test improvements
  • Highlighting testing anti-patterns
  • Providing templates for common testing patterns

Benefits

• More reliable and maintainable tests
• Better test coverage
• Faster test execution
• Clearer test failures
• Consistent testing approach across the project