Uber Go 语言编程规范：表格驱动测试

请使用带 subtests 的表格驱动测试，以避免在核心测试逻辑重复时额外的写很多重复的测试代码。

Bad

// func TestSplitHostPort(t *testing.T)

host, port, err := net.SplitHostPort("192.0.2.0:8000")
require.NoError(t, err)
assert.Equal(t, "192.0.2.0", host)
assert.Equal(t, "8000", port)

host, port, err = net.SplitHostPort("192.0.2.0:http")
require.NoError(t, err)
assert.Equal(t, "192.0.2.0", host)
assert.Equal(t, "http", port)

host, port, err = net.SplitHostPort(":8000")
require.NoError(t, err)
assert.Equal(t, "", host)
assert.Equal(t, "8000", port)

host, port, err = net.SplitHostPort("1:8")
require.NoError(t, err)
assert.Equal(t, "1", host)
assert.Equal(t, "8", port)

Good 

// func TestSplitHostPort(t *testing.T)

tests := []struct{
  give     string
  wantHost string
  wantPort string
}{
  {
    give:     "192.0.2.0:8000",
    wantHost: "192.0.2.0",
    wantPort: "8000",
  },
  {
    give:     "192.0.2.0:http",
    wantHost: "192.0.2.0",
    wantPort: "http",
  },
  {
    give:     ":8000",
    wantHost: "",
    wantPort: "8000",
  },
  {
    give:     "1:8",
    wantHost: "1",
    wantPort: "8",
  },
}

for _, tt := range tests {
  t.Run(tt.give, func(t *testing.T) {
    host, port, err := net.SplitHostPort(tt.give)
    require.NoError(t, err)
    assert.Equal(t, tt.wantHost, host)
    assert.Equal(t, tt.wantPort, port)
  })
}

表格驱动测试更容易为错误消息添加上下文，减少重复的逻辑，并很方便添加新的测试用例。

我们遵循的惯例是，将结构体的slice称为tests 和每个测试用例为tt。此外，我们鼓励用give和want前缀来解释每个测试用例的输入和输出值。

tests := []struct{
  give     string
  wantHost string
  wantPort string
}{
  // ...
}

for _, tt := range tests {
  // ...
}