# Go Testing Code Review

> Reviews Go test code for proper table-driven tests, assertions, and coverage patterns. Use when reviewing *_test.go files.

- Skill: `openshift/go-testing-code-review` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add openshift/go-testing-code-review`
- Raw SKILL.md: https://api.skillmd.com/api/skills/openshift/go-testing-code-review/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: openshift (https://skillmd.com/u/openshift)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/openshift/go-testing-code-review

---


# Go Testing Code Review

This codebase primarily uses the standard `testing` package (not Ginkgo) for controller and CLI tests; keep the Ginkgo/envtest bullets for when they apply or for cross-repo consistency.

## Quick Reference

| Issue Type | Reference |
|------------|-----------|
| Test structure, naming | [references/structure.md](references/structure.md) |
| Mocking, interfaces | [references/mocking.md](references/mocking.md) |

## Review Checklist

### File Organization
- [ ] Test file naming: All test files follow `*_test.go` convention (e.g., `reconciler_test.go` for `reconciler.go`)
- [ ] Co-location: Unit tests are in the same package as the code they test

### Standard Go Testing
- [ ] Tests are table-driven with clear case names
- [ ] Subtests use t.Run for parallel execution
- [ ] Test names describe behavior, not implementation
- [ ] Errors include got/want with descriptive message
- [ ] Cleanup registered with t.Cleanup
- [ ] Parallel tests don't share mutable state
- [ ] Mocks use interfaces defined in test file
- [ ] Coverage includes edge cases and error paths

### Ginkgo/Gomega (BDD Framework)
- [ ] Use `Describe` for test suites, `Context` for scenarios, `It` for test cases
- [ ] Setup/teardown in `BeforeEach`/`AfterEach` for proper isolation
- [ ] Assertions use `Expect()` with matchers (`To()`, `NotTo()`)
- [ ] Complex nested contexts organized logically (not too flat, not too deep)
- [ ] Use `By()` for multi-step test documentation

### Kubernetes/Controller Testing
- [ ] Controller tests use `envtest` for realistic API server testing
- [ ] Test fixtures cleaned up properly (remove finalizers before deletion)
- [ ] Owner references validated on created resources
- [ ] Reconciliation loops tested with eventual consistency (`Eventually()`)
- [ ] Both success and error paths tested for each reconcile function

## Critical Patterns

### Table-Driven Tests

```go
// BAD - repetitive
func TestAdd(t *testing.T) {
    if Add(1, 2) != 3 {
        t.Error("wrong")
    }
    if Add(0, 0) != 0 {
        t.Error("wrong")
    }
}

// GOOD
func TestAdd(t *testing.T) {
    tests := []struct {
        name     string
        a, b     int
        want     int
    }{
        {"positive numbers", 1, 2, 3},
        {"zeros", 0, 0, 0},
        {"negative", -1, 1, 0},
    }

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            got := Add(tt.a, tt.b)
            if got != tt.want {
                t.Errorf("Add(%d, %d) = %d, want %d", tt.a, tt.b, got, tt.want)
            }
        })
    }
}
```

### Error Messages

```go
// BAD
if got != want {
    t.Error("wrong result")
}

// GOOD
if got != want {
    t.Errorf("GetUser(%d) = %v, want %v", id, got, want)
}

// For complex types
if diff := cmp.Diff(want, got); diff != "" {
    t.Errorf("GetUser() mismatch (-want +got):\n%s", diff)
}
```

### Parallel Tests

```go
func TestFoo(t *testing.T) {
    tests := []struct{...}

    for _, tt := range tests {
        tt := tt  // capture (not needed Go 1.22+)
        t.Run(tt.name, func(t *testing.T) {
            t.Parallel()
            // test code
        })
    }
}
```

### Cleanup

```go
// BAD - manual cleanup, skipped on failure
func TestWithTempFile(t *testing.T) {
    f, _ := os.CreateTemp("", "test")
    defer os.Remove(f.Name())  // skipped if test panics
}

// GOOD
func TestWithTempFile(t *testing.T) {
    f, _ := os.CreateTemp("", "test")
    t.Cleanup(func() {
        os.Remove(f.Name())
    })
}
```

## Anti-Patterns

### 1. Testing Internal Implementation

```go
// BAD - tests private state
func TestUser(t *testing.T) {
    u := NewUser("alice")
    if u.id != 1 {  // testing internal field
        t.Error("wrong id")
    }
}

// GOOD - tests behavior
func TestUser(t *testing.T) {
    u := NewUser("alice")
    if u.ID() != 1 {
        t.Error("wrong ID")
    }
}
```

### 2. Shared Mutable State

```go
// BAD - tests interfere with each other
var testDB = setupDB()

func TestA(t *testing.T) {
    t.Parallel()
    testDB.Insert(...)  // race!
}

// GOOD - isolated per test
func TestA(t *testing.T) {
    db := setupTestDB(t)
    t.Cleanup(func() { db.Close() })
    db.Insert(...)
}
```

### 3. Assertions Without Context

```go
// BAD
assert.Equal(t, want, got)  // "expected X got Y" - which test?

// GOOD
assert.Equal(t, want, got, "user name after update")
```

## When to Load References

- Reviewing test file structure → structure.md
- Reviewing mock implementations → mocking.md

## Review Questions

1. Are tests table-driven with named cases?
2. Do error messages include input, got, and want?
3. Are parallel tests isolated (no shared state)?
4. Is cleanup done via t.Cleanup?
5. Do tests verify behavior, not implementation?