Agent skill
go-testing-code-review
Reviews Go test code for proper table-driven tests, assertions, and coverage patterns. Use when reviewing *_test.go files.
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Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/testing/go-testing-code-review-existential-birds-beagle
SKILL.md
Go Testing Code Review
Quick Reference
| Issue Type | Reference |
|---|---|
| Test structure, naming | references/structure.md |
| Mocking, interfaces | references/mocking.md |
Review Checklist
- 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
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
- Are tests table-driven with named cases?
- Do error messages include input, got, and want?
- Are parallel tests isolated (no shared state)?
- Is cleanup done via t.Cleanup?
- Do tests verify behavior, not implementation?
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