}
	t.reqCanceler[req] = cancel
	t.reqMu.Unlock()
	return cancel
}

// CancelRequest cancels an in-flight request by closing its connection.
// CancelRequest should only be called after [Transport.RoundTrip] has returned.
//
// Deprecated: Use [Request.WithContext] to create a request with a
// cancelable context instead. CancelRequest cannot cancel HTTP/2
// requests. This may become a no-op in a future release of Go.

}

// runCancelTestTransport uses Transport.CancelRequest.
func runCancelTestTransport(t *testing.T, mode testMode, f func(t *testing.T, test cancelTest)) {
	t.Run("TransportCancel", func(t *testing.T) {
		f(t, cancelTest{
			mode: mode,
			newReq: func(req *Request) *Request {
				return req
			},
			cancel: func(tr *Transport, req *Request) {
				tr.CancelRequest(req)
			},

			// ReadCloser, that will result in concurrent calls to Close (and possibly a
			// Read concurrent with a Close).
			if mode == http2Mode {
				close(cancel)
			} else {
				proxy.c.Transport.(*Transport).CancelRequest(req2)
			}
			rw.Write([]byte("OK"))
		}))
		defer proxy.close()

		req, _ := NewRequest("POST", proxy.ts.URL, io.LimitReader(neverEnding('a'), bodySize))
		res, err := proxy.c.Do(req)