go-testing_skill

Overview

This skill teaches Go testing best practices focused on maintainability and reliability. It covers table-driven tests, subtests, cleanup, race detection, coverage, and practical mocking strategies for real-world Go codebases. Use it to write, review, or improve Go test suites with concrete patterns and templates.

How this skill works

The skill inspects testing scenarios and recommends patterns: table-driven tests for input variations, t.Run for subtests, TestMain and t.Cleanup for lifecycle management, and race detection for concurrent code. It suggests when to prefer fakes or small interfaces over heavy mocking, how to structure test files and testdata, and commands to measure coverage and run the race detector.

When to use it

• Writing tests for functions with multiple input/output cases
• Reviewing tests for concurrency or flaky behavior
• Adding or improving integration tests and coverage measurement
• Refactoring tests to reduce duplication and improve readability
• Choosing between fakes, interfaces, and generated mocks

Best practices

• Use table-driven tests with descriptive case names and subtests (t.Run)
• Prefer t.Cleanup for per-test teardown to ensure cleanup runs even on failure
• Run tests with -race for any concurrent code and fix race reports promptly
• Prefer real small fakes or interfaces over complex mocking; only generate mocks when necessary
• Measure coverage with go test -cover and -coverprofile, but focus on meaningful tests not just percentage

Example use cases

• Unit testing an HTTP handler with table-driven cases for valid/invalid requests
• Testing a service with TestMain for shared setup and t.Cleanup for per-test teardown
• Detecting and fixing data races in goroutine-heavy code using go test -race
• Improving test suite organization: testdata/golden files, testutil helpers, and generated mocks when integration is impractical
• Reviewing a pull request to ensure tests are deterministic, cover edge cases, and use clear failure messages