/golang-testing

name: golang-testing
description: "Production-ready Golang tests — table-driven tests, testify suites and mocks, parallel tests, fuzzing, fixtures, goroutine leak detection with goleak, snapshot testing, code coverage, integration tests, idiomatic test naming. Use when writing or reviewing Go tests, choosing a testing approach, setting up Go test CI, or debugging flaky/slow tests. For testify-specific APIs see `samber/cc-skills-golang@golang-stretchr-testify`; for measurement methodology see `samber/cc-skills-golang@golang-benchmark`."
user-invocable: true
license: MIT
compatibility: Designed for Claude Code, Codex or similar harness, and for projects using Golang.
metadata:
  author: samber
  version: "1.4.0"
  openclaw:
    emoji: "🧪"
    homepage: https://github.com/samber/cc-skills-golang
    requires:
      bins:
        - go
        - gotests
    install:
      - kind: go
        package: github.com/cweill/gotests/gotests@latest
        bins: [gotests]
allowed-tools: Read Edit Write Glob Grep Bash(go:*) Bash(golangci-lint:*) Bash(git:*) Agent Bash(gotests:*) AskUserQuestion
paths:
  - "**/*.go"

**Persona:** You are a Go engineer who treats tests as executable specifications. You write tests to constrain behavior, not to hit coverage targets.

**Thinking mode:** Reason as thoroughly as possible for test strategy design and failure analysis — shallow reasoning misses edge cases and produces brittle tests that pass today but break tomorrow. On Claude Code, use `ultrathink` to trigger extended thinking explicitly.

**Orchestration mode:** Fan out the three sub-agents described in Audit mode (unit quality and coverage gaps, integration isolation, goroutine/race issues) for auditing a large test suite, and merge their findings into one gap report. On Claude Code, use `ultracode` to opt into multi-agent orchestration explicitly.

**Modes:**

• **Write mode** — generating new tests for existing or new code. Work sequentially through the code under test; use `gotests` to scaffold table-driven tests, then enrich with edge cases and error paths.
• **Review mode** — reviewing a PR's test changes. Focus on the diff: check coverage of new behaviour, assertion quality, table-driven structure, and absence of flakiness patterns. Sequential.
• **Audit mode** — auditing an existing test suite for gaps, flakiness, or bad patterns (order-dependent tests, missing `t.Parallel()`, implementation-detail coupling). Launch up to 3 parallel sub-agents split by concern: (1) unit test quality and coverage gaps, (2) integration test isolation and build tags, (3) goroutine leaks and race conditions.
• **Debug mode** — a test is failing or flaky. Work sequentially: reproduce reliably, isolate the failing assertion, trace the root cause in production code or test setup.

> **Community default.** A company skill that explicitly supersedes `samber/cc-skills-golang@golang-testing` skill takes precedence.

**Dependencies:**

• gotests: `go install github.com/cweill/gotests/gotests@latest`

Go Testing Best Practices

This skill guides the creation of production-ready tests for Go applications. Follow these principles to write maintainable, fast, and reliable tests.

Best Practices Summary

1. Table-driven tests MUST use named subtests -- every test case needs a `name` field passed to `t.Run` 2. Integration tests MUST use build tags (`//go:build integration`) to separate from unit tests 3. Tests MUST NOT depend on execution order -- each test MUST be independently runnable 4. Independent tests SHOULD use `t.Parallel()` when possible 5. Tests MUST assert observable behavior and public API contracts, not implementation details -- a test coupled to internals turns every refactor into a test rewrite while proving nothing about the contract 6. Packages with goroutines SHOULD use `goleak.VerifyTestMain` in `TestMain` to detect goroutine leaks 7. Use testify as helpers, not a replacement for standard library 8. Mock interfaces, not concrete types 9. Keep unit tests fast (< 1ms), use build tags for integration tests 10. Run tests with race detection in CI 11. Include examples as executable documentation 12. Test files MUST be named after the source file under test, not after the function or method being tested 13. Test functions SHOULD appear in the same order as the functions/methods they test in the source file

Test Structure and Organization

File Conventions

// package_test.go - tests in same package (white-box, access unexported)
package mypackage

// mypackage_test.go - tests in test package (black-box, public API only)
package mypackage_test

Name the test file after the source file it tests, not after the function or method under test. Go's convention is one test file per source file (`foo.go` -> `foo_test.go`), because tools (`go test`, coverage reports, IDE "jump to test" navigation, `gotests`) and reviewers all resolve tests by source file, not by symbol. A source file usually declares several functions/methods; splitting its tests by symbol name scatters them across many files and breaks that file-to-file mapping.

// ✓ Good — one test file per source file
helloworld.go       -> helloworld_test.go   // contains TestHelloWorld, TestAbcd, TestXyz, ...

// ✗ Bad — test file named after the function/method instead of the source file
helloworld.go       -> abcd_test.go         // wrong: should be helloworld_test.go

Exception: very large source files MAY be split into multiple `_test.go` files by concern (e.g. `foo_test.go` + `foo_edgecases_test.go`), but each split file's name MUST still be derived from the source file name, never from an individual function name. Prefer keeping a single `_test.go` file per source file even when it grows large — splitting adds navigation overhead and is rarely worth it; reach for the exception only when a single file becomes genuinely unwieldy to browse or review.

Within a test file, order test functions to match the order their tested functions