testing: handle panics in subtests in order to print errors and log info

[stephens2424]

What version of Go are you using (go version)?

1.10.1

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

OS X, Windows, App Engine (playground)

What did you do?

https://play.golang.org/p/4-VN_VdQnrc

What did you expect to see?

I expected to see the error that occurred to be printed, and then the panic.

What did you see instead?

I see only the panic.

The exact use case I have is a table test where each subtest is using a different version of an external resource (message queue). An early subtest fails to perform some setup and leaves an internal thing in a bad state, so I expect my tests to not work fully at this point. However, because the later subtest panics when it encounters that bad state, the whole test function aborts without my previous calls to t.Error or t.Fatal (in the previous subtest) having their contents printed. Because of this, I lost critical error information that would have pointed me to the real issue with the earlier subtest's setup. Since the earlier subtest didn't print anything, its problem was not apparent.

[meirf]

This behavior has been around since 1.7, which is when subtest support was added.
(That's not to say this behavior is okay - just that it's unlikely there's a recent commit that's causing this.)

[ianlancetaylor]

CC @mpvl

[gopherbot]

Change https://golang.org/cl/123921 mentions this issue: testing: handle panics in subtests to print previous output

[andrewmed]

Hi. This is "help wanted" and "needs fix".
Last commit is from Emmanuel Odeke, it adds missing test, but it is from February.
If help is still needed and no one objects, I am glad to pick this up.