using t.Fatal in a goroutine

[whyrusleeping]

Apparently (it makes sense thinking about it) you can't use t.Fatal in a goroutine.

A cursory search reveals at least a few occurences of this bug: https://gist.github.com/whyrusleeping/6ff875746eccfc2611ab

Lots of them in our dependencies unfortunately, but a few in our code:
exchange/bitswap/bitswap_test.go-173
fuse/readonly/ipfs_test.go-160
merkledag/merkledag_test.go-198-
test/supernode_client/main.go-145-
test/supernode_client/main.go-183

[chriscool]

@whyrusleeping is there something else that should be used instead?

[whyrusleeping]

the errors need to be somehow propogated back to the main goroutine (the one executing the Test* function) and t.Fatal needs to be called there.

[chriscool]

Ok, thanks!

[jbenet]

Here are some examples of what i do:

example:

func TestSimpleAsync(t *testing.T) {

    // use a channel to hand off the error
    errs := make(chan error, 1)
    go func() {
        err := somethingAsync()
        errs <- err
    }()

    // wait for it
    err := <-errs
    if err != nil {
        t.Fatal(err)
    }
}

func TestNAsync(t *testing.T) {

    // we're going to have N children
    N := 10

    // use a channel to hand off the error
    errs := make(chan error, N)
    for i := 0; i < N; i++ {
        go func() {
            err := somethingAsync()
            errs <- err
        }()
    }

    // wait for all N to finish
    for i := 0; i < N; i++ {
        err := <-errs
        if err != nil {
            t.Fatal(err)
        }
    }
}

func TestManyAsync(t *testing.T) {

    var wg sync.WaitGroup
    errs := make(chan error, 10)

    for shouldKeepGoing() {

        wg.Add(1)
        go func() {
            defer wg.Done()

            err := somethingAsync()
            if err != nil {
                errs <- err
            }
        }()
    }

    // close errs once all children finish.
    // wg allows us to do this without knowing
    // how many children a priori.
    go func() {
        wg.Wait()
        close(errs)
    }()

    for err := range errs {
        if err != nil {
            t.Fatal(err)
        }
    }
}

[whyrusleeping]

We should verify that all occurences of this have been resolved, then close the issue

[Stebalien]

Closing because, realistically, nobody's going to audit every one of our repos for this.