testing: confusing failures when t.Error called after test has returned

[neild]

Pre-1.7, calling t.Error after a Test function returned had no effect. Now it causes the test suite to fail, but (confusingly) the cause of the failure isn't reported in any way.

package t_test

import (
        "testing"
        "time"
)

func TestA(t *testing.T) {
        go func() {
                time.Sleep(10 * time.Millisecond)
                t.Errorf("failed after success")
        }()
}

func TestB(t *testing.T) {
        time.Sleep(1 * time.Second)
}

$ go version
go version go1.6 linux/amd64
$ go test . -test.v
=== RUN   TestA
--- PASS: TestA (0.00s)
=== RUN   TestB
--- PASS: TestB (1.00s)
PASS
ok      _/usr/local/google/home/dneil/src/testex        1.022s

$ ~/go/bin/go version
go version devel +15285d4 Wed Apr 27 11:08:58 2016 -0700 linux/amd64
$ ~/go/bin/go test . -test.v
=== RUN   TestA
--- PASS: TestA (0.00s)
=== RUN   TestB
--- PASS: TestB (1.00s)
FAIL
exit status 1
FAIL    _/usr/local/google/home/dneil/src/testex        1.013s

The test is clearly at fault, so this becoming a failure isn't a problem at all. However, it's not at all obvious why the test has failed; every test passes and then the test run fails inexplicably.

[josharian]

@mpvl

[gopherbot]

CL https://golang.org/cl/23065 mentions this issue.

[gopherbot]

CL https://golang.org/cl/23320 mentions this issue.