Stop()
	size := buf.Len()
	if size == 0 {
		t.Fatalf("trace is empty")
	}
	time.Sleep(100 * time.Millisecond)
	if size != buf.Len() {
		t.Fatalf("trace writes after stop: %v -> %v", size, buf.Len())
	}
	saveTrace(t, buf, "TestTraceStartStop")
}

func TestTraceDoubleStart(t *testing.T) {
	if IsEnabled() {
		t.Skip("skipping because -test.trace is set")
	}
	Stop()
	buf := new(bytes.Buffer)