EventuallyWithT does not always copy the last errors

[cszczepaniak]

The documentation for EventuallyWithT states:

// If the condition is not met before waitFor, the collected errors of
// the last tick are copied to t.

However, it is possible to show that this is not the case with the following test:

func TestEventuallyWithTFalse(t *testing.T) {
	mockT := new(CollectT)

	var calledOnce bool
	condition := func(collect *CollectT) {
		if calledOnce {
			time.Sleep(time.Second)
		}
		True(collect, false)
		calledOnce = true
	}

	False(t, EventuallyWithT(mockT, condition, 100*time.Millisecond, 20*time.Millisecond))
	Len(t, mockT.errors, 2)
}

This test fails because the errors do not get copied; there is a race condition condition between the condition-checking goroutine and the assertion's goroutine.

[cszczepaniak]

This is potentially a duplicate of #1395; this issue reports the symptom of what #1395 reports.

[cszczepaniak]

Closing this because there are plenty of similar issues already.