WIP: Run unit & integration tests with go test -race

[DMRobertson]

No description provided.

[kegsay]

If CI is happy, LGTM. What a faff. It would be easier to just use an atomic.Bool for closing perhaps?

[DMRobertson]

What a faff.

Yes. I think I'm holding something wrong here.

According to https://go.dev/tour/concurrency/4 (I wish there was a more authoritative reference):

Another note: Channels aren't like files; you don't usually need to close them. Closing is only necessary when the receiver must be told there are no more values coming, such as to terminate a range loop.

I think The Right Thing might be to make PubSub.Close not close channels?

[kegsay]

If you don't close channels and the channel is spread over >1 goroutine, then the goroutine will leak in cases where you have:

go func() {
    for val := range ch {
    }
}()

as the for loop only terminates when the channel is closed.

[kegsay]

I did half of this in #337 - need to go through the data races in integ tests.

[kegsay]

#410