}
func testServerRequestContextCancel_ServeHTTPDone(t *testing.T, mode testMode) {
	ctxc := make(chan context.Context, 1)
	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
		ctx := r.Context()
		select {
		case <-ctx.Done():
			t.Error("should not be Done in ServeHTTP")
		default:
		}
		ctxc <- ctx
	}))
	res, err := cst.c.Get(cst.ts.URL)
	if err != nil {
		t.Fatal(err)