t.Fatal("broken")
	}
	if mu.RWLock(true) {
		t.Fatal("broken")
	}
	if mu.RWLock(false) {
		t.Fatal("broken")
	}
	if mu.IncrefAndClose() {
		t.Fatal("broken")
	}
}

func TestMutexCloseUnblock(t *testing.T) {
	c := make(chan bool, 4)
	var mu XFDMutex
	mu.RWLock(true)
	for i := 0; i < 4; i++ {
		go func() {
			if mu.RWLock(true) {
				t.Error("broken")
				return
			}
			c <- true