golang-testing

What this skill does

When applied, it prepends a system prompt before your request is sent — no extra calls and no change to how you are billed beyond the added tokens.

---
name: golang-testing
description: Go testing patterns including table-driven tests, subtests, benchmarks, fuzzing, and test coverage. Follows TDD methodology with idiomatic Go practices.
---

# Go 測試模式

用於撰寫可靠、可維護測試的完整 Go 測試模式，遵循 TDD 方法論。

## 何時啟用

- 撰寫新的 Go 函式或方法
- 為現有程式碼增加測試覆蓋率
- 為效能關鍵程式碼建立基準測試
- 實作輸入驗證的模糊測試
- 在 Go 專案中遵循 TDD 工作流程

## Go 的 TDD 工作流程

### RED-GREEN-REFACTOR 循環

```
RED     → 先寫失敗的測試
GREEN   → 撰寫最少程式碼使測試通過
REFACTOR → 在保持測試綠色的同時改善程式碼
REPEAT  → 繼續下一個需求
```

### Go 中的逐步 TDD

```go
// 步驟 1：定義介面/簽章
// calculator.go
package calculator

func Add(a, b int) int {
    panic("not implemented") // 佔位符
}

// 步驟 2：撰寫失敗測試（RED）
// calculator_test.go
package calculator

import "testing"

func TestAdd(t *testing.T) {
    got := Add(2, 3)
    want := 5
    if got != want {
        t.Errorf("Add(2, 3) = %d; want %d", got, want)
    }
}

// 步驟 3：執行測試 - 驗證失敗
// $ go test
// --- FAIL: TestAdd (0.00s)
// panic: not implemented

// 步驟 4：實作最少程式碼（GREEN）
func Add(a, b int) int {
    return a + b
}

// 步驟 5：執行測試 - 驗證通過
// $ go test
// PASS

// 步驟 6：如需要則重構，驗證測試仍然通過
```

## 表格驅動測試

Go 測試的標準模式。以最少程式碼達到完整覆蓋。

```go
func TestAdd(t *testing.T) {
    tests := []struct {
        name     string
        a, b     int
        expected int
    }{
        {"positive numbers", 2, 3, 5},
        {"negative numbers", -1, -2, -3},
        {"zero values", 0, 0, 0},
        {"mixed signs", -1, 1, 0},
        {"large numbers", 1000000, 2000000, 3000000},
    }

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

### 帶錯誤案例的表格驅動測試

```go
func TestParseConfig(t *testing.T) {
    tests := []struct {
        name    string
        input   string
        want    *Config
        wantErr bool
    }{
        {
            name:  "valid config",
            input: `{"host":

Use this skill

{
  "model": "gpt-4o-mini",
  "skill": "imp-14973371-447b-43ff-afb4-a4039a6f532d",
  "messages": [{ "role": "user", "content": "…" }]
}

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