code review 12632043: net/http: fix early side effects in the ResponseWriter'...

src/pkg/net/http/serve_test.go

 // Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // End-to-end serving tests
 
 package http_test
 
 import (
         "bufio"
@@ skipping 1797 matching lines @@
                 conn.Close()
                 resp.Body.Close()
 
                 got := resp.Header["Connection"]
                 if !reflect.DeepEqual(got, tt.expect) {
                         t.Errorf("wrong Connection headers for request %q. Got %q expect %q", got, tt.expect)
                 }
         }
 }
 
+// See golang.org/issue/5660
+func TestServerReaderFromOrder(t *testing.T) {
+        defer afterTest(t)
+        pr, pw := io.Pipe()
+        const size = 3 << 20
+        ts := httptest.NewServer(HandlerFunc(func(rw ResponseWriter, req *Request) {
+                rw.Header().Set("Content-Type", "text/plain") // prevent sniffing path
+                done := make(chan bool)
+                go func() {
+                        io.Copy(rw, pr)
+                        close(done)
+                }()
+                time.Sleep(25 * time.Millisecond) // give Copy a chance to break things
+                n, err := io.Copy(ioutil.Discard, req.Body)
+                if err != nil {
+                        t.Errorf("handler Copy: %v", err)
+                        return
+                }
+                if n != size {
+                        t.Errorf("handler Copy = %d; want %d", n, size)
+                }
+                pw.Write([]byte("hi"))
+                pw.Close()
+                <-done
+        }))
+        defer ts.Close()
+
+        req, err := NewRequest("POST", ts.URL, io.LimitReader(neverEnding('a'), size))
+        if err != nil {
+                t.Fatal(err)
+        }
+        res, err := DefaultClient.Do(req)
+        if err != nil {
+                t.Fatal(err)
+        }
+        all, err := ioutil.ReadAll(res.Body)
+        if err != nil {
+                t.Fatal(err)
+        }
+        res.Body.Close()
+        if string(all) != "hi" {
+                t.Errorf("Body = %q; want hi", all)
+        }
+}
+
 func BenchmarkClientServer(b *testing.B) {
         b.ReportAllocs()
         b.StopTimer()
         ts := httptest.NewServer(HandlerFunc(func(rw ResponseWriter, r *Request) {
                 fmt.Fprintf(rw, "Hello world.\n")
         }))
         defer ts.Close()
         b.StartTimer()
 
         for i := 0; i < b.N; i++ {
@@ skipping 277 matching lines @@
                 handled++
                 h.ServeHTTP(rw, r)
         })
         ln := &oneConnListener{conn: conn}
         go Serve(ln, handler)
         <-conn.closec
         if b.N != handled {
                 b.Errorf("b.N=%d but handled %d", b.N, handled)
         }
 }