# Go Testing Subtests

> Subtest patterns with t.Run Use when this capability is needed.

- Skill: `tomevault-io/go-testing-subtests` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/go-testing-subtests`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/go-testing-subtests/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/go-testing-subtests

---


# Subtests with t.Run

Use t.Run to group related tests and enable selective execution.

## CORRECT

```go
func Test_User_Validation(t *testing.T) {
    t.Run("valid email", func(t *testing.T) {
        user := User{Email: "test@example.com"}
        if err := user.Validate(); err != nil {
            t.Errorf("expected valid, got error: %v", err)
        }
    })

    t.Run("invalid email", func(t *testing.T) {
        user := User{Email: "invalid"}
        if err := user.Validate(); err == nil {
            t.Error("expected error, got nil")
        }
    })

    t.Run("empty email", func(t *testing.T) {
        user := User{Email: ""}
        if err := user.Validate(); err == nil {
            t.Error("expected error, got nil")
        }
    })
}
```

**Run specific subtest:**
```bash
go test -run Test_User_Validation/invalid_email
```

**Why:**
- Logical grouping of related tests
- Can run subtests individually
- Clean test output with hierarchy
- Failures don't stop other subtests

## WRONG

```go
func Test_User_ValidEmail(t *testing.T) { /* ... */ }
func Test_User_InvalidEmail(t *testing.T) { /* ... */ }
func Test_User_EmptyEmail(t *testing.T) { /* ... */ }
```

**Problems:**
- No grouping relationship
- Harder to run related tests together
- More verbose test names

---
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<!-- tomevault:4.0:skill_md:2026-04-13 -->