在并行模式下，go测试以json格式输出错误的大小写

Question

go版本: 1.18.1

假设我编写了这个测试文件parallel_test.go

package parallel_json_output

import (
    "fmt"
    "testing"
    "time"
)

func TestP(t *testing.T) {
    t.Run("a", func(t *testing.T) {
        t.Parallel()
        for i := 0; i < 5; i++ {
            time.Sleep(time.Second)
            fmt.Println("a", i)
        }
    })
    t.Run("b", func(t *testing.T) {
        t.Parallel()
        for i := 0; i < 5; i++ {
            time.Sleep(time.Second)
            fmt.Println("b", i)
        }
    })
}

在运行go test parallel_test.go -v -json之后，我

{"Time":"2022-06-11T02:48:10.3262833+08:00","Action":"run","Package":"command-line-arguments","Test":"TestP"}
{"Time":"2022-06-11T02:48:10.3672856+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP","Output":"=== RUN   TestP\n"}
{"Time":"2022-06-11T02:48:10.3682857+08:00","Action":"run","Package":"command-line-arguments","Test":"TestP/a"}
{"Time":"2022-06-11T02:48:10.3682857+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/a","Output":"=== RUN   TestP/a\n"}
{"Time":"2022-06-11T02:48:10.3692857+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/a","Output":"=== PAUSE TestP/a\n"}
{"Time":"2022-06-11T02:48:10.3702858+08:00","Action":"pause","Package":"command-line-arguments","Test":"TestP/a"}
{"Time":"2022-06-11T02:48:10.3702858+08:00","Action":"run","Package":"command-line-arguments","Test":"TestP/b"}
{"Time":"2022-06-11T02:48:10.3712858+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"=== RUN   TestP/b\n"}
{"Time":"2022-06-11T02:48:10.3712858+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"=== PAUSE TestP/b\n"}
{"Time":"2022-06-11T02:48:10.3722859+08:00","Action":"pause","Package":"command-line-arguments","Test":"TestP/b"}
{"Time":"2022-06-11T02:48:10.373286+08:00","Action":"cont","Package":"command-line-arguments","Test":"TestP/a"}
{"Time":"2022-06-11T02:48:10.373286+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/a","Output":"=== CONT  TestP/a\n"}
{"Time":"2022-06-11T02:48:10.374286+08:00","Action":"cont","Package":"command-line-arguments","Test":"TestP/b"}
{"Time":"2022-06-11T02:48:10.374286+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"=== CONT  TestP/b\n"}
{"Time":"2022-06-11T02:48:11.3352891+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"b 0\n"}
{"Time":"2022-06-11T02:48:11.3352891+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"a 0\n"}
...

看看这行{"Time":"2022-06-11T02:48:11.3352891+08:00","Action":"output","Package":"command-line-arguments","Test":"TestP/b","Output":"a 0\n"}。这个输出应该由case TestP/a而不是b打印，但是输出在并行测试中混淆了用例的名称。

这个问题使得报表工具生成错误的HTML，IDE(如GoLand)也会受到影响，无法正确排序并行输出。

我在Github 这里中发现了它的一个问题，但是这个问题似乎已经在go 1.14.6中解决了，但是它仍然出现在go 1.18中。我想知道发生了什么以及如何处理，非常感谢。

Answer 1

通用fmt包对并发环境中当前执行的测试知之甚少，这是有意义的。

测试包有自己的Log方法，可以正确地呈现当前测试：

t.Log("a", i)