Goleak detects leaked goroutines from other tests

[denis-tingaikin]

Description

We've found an interesting thing during using goleak on our CI, that goleak can detect leaked goroutine from other tests.

Steps to reproduce

1. Use go1.14.1 darwin/amd64
2. Use goleak v1.0.0
3. Run test file below
   goleak_test.go

package goleak_test

import (
	"go.uber.org/goleak"
	"testing"
	"time"
)

func TestA(t *testing.T) {
	go func() {
		for {
			<-time.After(time.Millisecond * 100)
		}
	}()
}

func TestB(t *testing.T) {
	defer goleak.VerifyNone(t)
}

Expected: TestB should pass
Actual: TestB fails with error "found unexpected goroutines:"

[prashantv]

Yes, this is expected, as goleak cannot determine which test specifically is responsible for a leak, it just identifies that there is a leak when VerifyNone is run. If you had the same defer goleak.VerifyNone(t) in TestAt, it would detect that test as leaking too.

You could run the leak detection at the beginning and end of a test to ensure there were none before the test is started,

func TestB(t *testing.T) {
	goleak.VerifyNone(t) // ensure there's no leaks before the test starts
	defer goleak.VerifyNone(t)
}

You could write your own helper for this as well.

[denis-tingaikin]

@prashantv thanks for the clarifications, I also got a question, can we add some option for goleak to ignore set of stacks. For example

func IngoreStacks(stacks ...stack.Stack) Option {
	excludeIDSet := map[int]bool{}
	for _, s := range stacks {
		excludeIDSet[s.ID()] = true
	}
	return addFilter(func(s stack.Stack) bool {
		return excludeIDSet[s.ID()],
	})
}

And with this option I could use the next options for the example above:

defer goleak.VerifyNone(t, goleak.IngoreStacks(stack.All()...))

What do you think about this approach? :)

[prashantv]

Fixed in #49