proposal: testing: Allow a unit test to specify that the process it runs in should not be reused by other unit tests.

[cwmos]

Some unit tests modify global variables in the process they run in. Currently, unit tests need to restore those variables when they are completed since the same process may be used to run other unit tests.

I propose to extend testing.T with a new function ExitProcess. When a unit test calls ExitProcess, a new process will be started for subsequent unit tests.

With this change, the following test would succeed:

package main 

import "testing"

var globalVariable = 42

func TestMyTest1(t *testing.T) {
  if globalVariable!=42 {
    t.Fail()
  }
  globalVariable=43
  t.ExitProcess()
}

func TestMyTest2(t *testing.T) {
  if globalVariable!=42 {
    t.Fail()
  }
  globalVariable=44
  t.ExitProcess()
}

The ExitProcess() function should probably not be supported for parallel tests.

[seankhliao]

Tests that need to run as an independent child process should probably do so explicitly, rather than only exiting after the test.
See https://go.dev/talks/2014/testing.slide#23

[bcmills]

See, for example, runtime.TestFinalizerRegisterABI.

[bitfield]

Some unit tests modify global variables in the process they run in.

I don't mean to sound flip, but there's your problem.

[cwmos]

Ok, does not seem like a lot of support for this, so I will close it.

Thanks for the input and the idea of starting a subprocess manually! I guess it would also be possible to get coverage reports in some way with this approach.