io: add test that MultiReader zeros exhausted Readers

Updates #16983
Updates #16996

Change-Id: I76390766385b2668632c95e172b2d243d7f66651
Reviewed-on: https://go-review.googlesource.com/28771
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/io/multi_test.go b/src/io/multi_test.go
index 339362eb8cd79772f5983270733accf07b73349f..16e351a87911ec0877f4b2f6c9d55dab0b116ce7 100644 (file)
--- a/src/io/multi_test.go
+++ b/src/io/multi_test.go
@@ -14,6 +14,7 @@ import (
        "runtime"
        "strings"
        "testing"
+       "time"
 )
 
 func TestMultiReader(t *testing.T) {
@@ -234,3 +235,32 @@ func TestMultiReaderFinalEOF(t *testing.T) {
                t.Errorf("got %v, %v; want 1, EOF", n, err)
        }
 }
+
+func TestMultiReaderFreesExhaustedReaders(t *testing.T) {
+       var mr Reader
+       closed := make(chan struct{})
+       {
+               buf1 := bytes.NewReader([]byte("foo"))
+               buf2 := bytes.NewReader([]byte("bar"))
+               mr = MultiReader(buf1, buf2)
+               runtime.SetFinalizer(buf1, func(*bytes.Reader) {
+                       close(closed)
+               })
+       }
+
+       buf := make([]byte, 4)
+       if n, err := ReadFull(mr, buf); err != nil || string(buf) != "foob" {
+               t.Fatalf(`ReadFull = %d (%q), %v; want 3, "foo", nil`, n, buf[:n], err)
+       }
+
+       runtime.GC()
+       select {
+       case <-closed:
+       case <-time.After(5 * time.Second):
+               t.Fatal("timeout waiting for collection of buf1")
+       }
+
+       if n, err := ReadFull(mr, buf[:2]); err != nil || string(buf[:2]) != "ar" {
+               t.Fatalf(`ReadFull = %d (%q), %v; want 2, "ar", nil`, n, buf[:n], err)
+       }
+}