mirror of
https://github.com/Rain-kl/OpenFlare.git
synced 2026-10-04 07:06:36 +08:00
ryan
132 lines
3.5 KiB
Markdown
132 lines
3.5 KiB
Markdown
# 测试辅助函数、断言和比较
|
||
|
||
编写测试辅助函数、避免断言库以及在 t.Error 和 t.Fatal 之间选择的详细参考。
|
||
来源：Google Go Style Guide、Uber Go Style Guide。
|
||
|
||
---
|
||
|
||
## 测试辅助函数模式
|
||
|
||
测试辅助函数必须首先调用 `t.Helper()`，使失败指向调用者。
|
||
对设置失败使用 `t.Fatal`，对清理使用 `t.Cleanup`。
|
||
|
||
```go
|
||
func mustLoadTestData(t *testing.T, filename string) []byte {
|
||
t.Helper()
|
||
data, err := os.ReadFile(filename)
|
||
if err != nil {
|
||
t.Fatalf("Setup failed: could not read %s: %v", filename, err)
|
||
}
|
||
return data
|
||
}
|
||
|
||
func setupTestDB(t *testing.T) *sql.DB {
|
||
t.Helper()
|
||
db, err := sql.Open("sqlite3", ":memory:")
|
||
if err != nil {
|
||
t.Fatalf("Could not open database: %v", err)
|
||
}
|
||
t.Cleanup(func() { db.Close() })
|
||
return db
|
||
}
|
||
```
|
||
|
||
**关键规则：**
|
||
- 将 `t.Helper()` 作为第一条语句调用，将失败归因于调用者
|
||
- 对设置失败使用 `t.Fatal`（不要从辅助函数返回错误）
|
||
- 使用 `t.Cleanup()` 进行清理而非 defer — 即使测试调用 `t.FailNow` 它也会执行
|
||
|
||
---
|
||
|
||
## 避免断言库
|
||
|
||
> **规范**：不要创建或使用断言库。
|
||
|
||
断言库会碎片化开发者体验，并且经常产生无用的失败信息。
|
||
|
||
```go
|
||
// 不好：
|
||
assert.IsNotNil(t, "obj", obj)
|
||
assert.StringEq(t, "obj.Type", obj.Type, "blogPost")
|
||
assert.IntEq(t, "obj.Comments", obj.Comments, 2)
|
||
|
||
// 好：使用 cmp 包和标准比较
|
||
want := BlogPost{
|
||
Type: "blogPost",
|
||
Comments: 2,
|
||
Body: "Hello, world!",
|
||
}
|
||
if diff := cmp.Diff(want, got); diff != "" {
|
||
t.Errorf("GetPost() mismatch (-want +got):\n%s", diff)
|
||
}
|
||
```
|
||
|
||
### 领域特定比较
|
||
|
||
对于领域特定比较，返回值或错误而非调用 `t.Error`：
|
||
|
||
```go
|
||
func postLength(p BlogPost) int { return len(p.Body) }
|
||
|
||
func TestBlogPost(t *testing.T) {
|
||
post := BlogPost{Body: "Hello"}
|
||
if got, want := postLength(post), 5; got != want {
|
||
t.Errorf("postLength(post) = %v, want %v", got, want)
|
||
}
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 比较和 Diff
|
||
|
||
对于复杂类型，优先使用 `cmp.Equal` 和 `cmp.Diff`。始终在 diff 信息中包含方向键 `(-want +got)`。
|
||
|
||
```go
|
||
// struct 比较
|
||
want := &Doc{Type: "blogPost", Authors: []string{"isaac", "albert"}}
|
||
if diff := cmp.Diff(want, got); diff != "" {
|
||
t.Errorf("AddPost() mismatch (-want +got):\n%s", diff)
|
||
}
|
||
|
||
// Protocol buffers
|
||
if diff := cmp.Diff(want, got, protocmp.Transform()); diff != "" {
|
||
t.Errorf("Foo() mismatch (-want +got):\n%s", diff)
|
||
}
|
||
```
|
||
|
||
**避免不稳定的比较** — 不要比较可能变化的 JSON/序列化输出。改为语义比较。
|
||
|
||
---
|
||
|
||
## t.Error vs t.Fatal：详细指南
|
||
|
||
使用 `t.Error` 保持测试继续运行，在一次运行中报告所有失败：
|
||
|
||
```go
|
||
// 好：报告所有不匹配
|
||
if diff := cmp.Diff(wantMean, gotMean); diff != "" {
|
||
t.Errorf("Mean mismatch (-want +got):\n%s", diff)
|
||
}
|
||
if diff := cmp.Diff(wantVariance, gotVariance); diff != "" {
|
||
t.Errorf("Variance mismatch (-want +got):\n%s", diff)
|
||
}
|
||
```
|
||
|
||
当后续检查无意义时使用 `t.Fatal`：
|
||
|
||
```go
|
||
gotEncoded := Encode(input)
|
||
if gotEncoded != wantEncoded {
|
||
t.Fatalf("Encode(%q) = %q, want %q", input, gotEncoded, wantEncoded)
|
||
}
|
||
gotDecoded, err := Decode(gotEncoded)
|
||
if err != nil {
|
||
t.Fatalf("Decode(%q) error: %v", gotEncoded, err)
|
||
}
|
||
```
|
||
|
||
### 不要从 Goroutine 中调用 t.Fatal
|
||
|
||
> **规范**：绝不在测试 goroutine 以外的 goroutine 中调用 `t.Fatal`、`t.Fatalf` 或 `t.FailNow`。改为使用 `t.Error` 并让 goroutine 自然返回。
|