Address review comments

http2/transport.go

@@ -1239,13 +1239,12 @@ func (cs *clientStream) writeRequest(req *http.Request) (err error) {
 	}
 
 	continueTimeout := cc.t.expectContinueTimeout()
-	if continueTimeout != 0 &&
-		!httpguts.HeaderValuesContainsToken(
-			req.Header["Expect"],
-			"100-continue") {
-		continueTimeout = 0
-	} else if continueTimeout != 0 {
-		cs.on100 = make(chan struct{}, 1)
+	if continueTimeout != 0 {
+		if !httpguts.HeaderValuesContainsToken(req.Header["Expect"], "100-continue") {
+			continueTimeout = 0
+		} else {
+			cs.on100 = make(chan struct{}, 1)
+		}
 	}
 
 	// Past this point (where we send request headers), it is possible for

http2/transport_test.go

@@ -5109,10 +5109,28 @@ func TestTransportServerResetStreamAtHeaders(t *testing.T) {
 	res.Body.Close()
 }
 
+type trackingReader struct {
+	rdr     io.Reader
+	wasRead uint32
+}
+
+func (tr *trackingReader) Read(p []byte) (int, error) {
+	atomic.StoreUint32(&tr.wasRead, 1)
+	return tr.rdr.Read(p)
+}
+
+func (tr *trackingReader) WasRead() bool {
+	return atomic.LoadUint32(&tr.wasRead) != 0
+}
+
 func TestTransportExpectContinue(t *testing.T) {
 	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
-		io.Copy(io.Discard, r.Body)
-		return
+		switch r.URL.Path {
+		case "/reject":
+			w.WriteHeader(403)
+		default:
+			io.Copy(io.Discard, r.Body)
+		}
 	}, optOnlyServer)
 	defer st.Close()
 
@@ -5130,31 +5148,54 @@ func TestTransportExpectContinue(t *testing.T) {
 		Transport: tr,
 	}
 
-	reqCh := make(chan error)
-	startTime := time.Now()
+	testCases := []struct {
+		Name         string
+		Path         string
+		Body         *trackingReader
+		ExpectedCode int
+		ShouldRead   bool
+	}{
+		{
+			Name:         "read-all",
+			Path:         "/",
+			Body:         &trackingReader{rdr: strings.NewReader("hello")},
+			ExpectedCode: 200,
+			ShouldRead:   true,
+		},
+		{
+			Name:         "reject",
+			Path:         "/reject",
+			Body:         &trackingReader{rdr: strings.NewReader("hello")},
+			ExpectedCode: 403,
+			ShouldRead:   false,
+		},
+	}
 
-	go func() {
-		req, err := http.NewRequest("POST", st.ts.URL, strings.NewReader("hello"))
-		if err != nil {
-			reqCh <- err
-			return
-		}
-		req.Header.Set("Expect", "100-continue")
-		res, err := client.Do(req)
-		if err != nil {
-			reqCh <- err
-			return
-		}
-		reqCh <- res.Body.Close()
-	}()
+	for _, tc := range testCases {
+		t.Run(tc.Name, func(t *testing.T) {
+			startTime := time.Now()
 
-	err = <-reqCh
-	if err != nil {
-		t.Fatal(err)
-	}
-	delta := time.Since(startTime)
-	if delta >= tr.ExpectContinueTimeout {
-		t.Error("Request didn't resume after receiving 100 continue")
+			req, err := http.NewRequest("POST", st.ts.URL+tc.Path, tc.Body)
+			if err != nil {
+				t.Fatal(err)
+			}
+			req.Header.Set("Expect", "100-continue")
+			res, err := client.Do(req)
+			if err != nil {
+				t.Fatal(err)
+			}
+			res.Body.Close()
+
+			if delta := time.Since(startTime); delta >= tr.ExpectContinueTimeout {
+				t.Error("Request didn't finish before expect continue timeout")
+			}
+			if res.StatusCode != tc.ExpectedCode {
+				t.Errorf("Unexpected status code, got %d, expected %d", res.StatusCode, tc.ExpectedCode)
+			}
+			if tc.Body.WasRead() != tc.ShouldRead {
+				t.Errorf("Unexpected read status, got %v, expected %v", tc.Body.WasRead(), tc.ShouldRead)
+			}
+		})
 	}
 }