bufio: add some tests

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7927044

diff --git a/src/pkg/bufio/bufio_test.go b/src/pkg/bufio/bufio_test.go
index b0e811443191bd2c053374197b48c6a6e7c0c869..79ed0f178e036ccab1ffb7b2fe166a6138267ecc 100644 (file)
--- a/src/pkg/bufio/bufio_test.go
+++ b/src/pkg/bufio/bufio_test.go
@@ -7,6 +7,7 @@ package bufio_test
 import (
        . "bufio"
        "bytes"
+       "errors"
        "fmt"
        "io"
        "io/ioutil"
@@ -434,9 +435,12 @@ func TestWriteErrors(t *testing.T) {
                        t.Errorf("Write hello to %v: %v", w, e)
                        continue
                }
-               e = buf.Flush()
-               if e != w.expect {
-                       t.Errorf("Flush %v: got %v, wanted %v", w, e, w.expect)
+               // Two flushes, to verify the error is sticky.
+               for i := 0; i < 2; i++ {
+                       e = buf.Flush()
+                       if e != w.expect {
+                               t.Errorf("Flush %d/2 %v: got %v, wanted %v", i+1, w, e, w.expect)
+                       }
                }
        }
 }
@@ -962,6 +966,43 @@ func TestNegativeRead(t *testing.T) {
        b.Read(make([]byte, 100))
 }
 
+var errFake = errors.New("fake error")
+
+type errorThenGoodReader struct {
+       didErr bool
+       nread  int
+}
+
+func (r *errorThenGoodReader) Read(p []byte) (int, error) {
+       r.nread++
+       if !r.didErr {
+               r.didErr = true
+               return 0, errFake
+       }
+       return len(p), nil
+}
+
+func TestReaderClearError(t *testing.T) {
+       r := &errorThenGoodReader{}
+       b := NewReader(r)
+       buf := make([]byte, 1)
+       if _, err := b.Read(nil); err != nil {
+               t.Fatalf("1st nil Read = %v; want nil", err)
+       }
+       if _, err := b.Read(buf); err != errFake {
+               t.Fatalf("1st Read = %v; want errFake", err)
+       }
+       if _, err := b.Read(nil); err != nil {
+               t.Fatalf("2nd nil Read = %v; want nil", err)
+       }
+       if _, err := b.Read(buf); err != nil {
+               t.Fatalf("3rd Read with buffer = %v; want nil", err)
+       }
+       if r.nread != 2 {
+               t.Errorf("num reads = %d; want 2", r.nread)
+       }
+}
+
 // An onlyReader only implements io.Reader, no matter what other methods the underlying implementation may have.
 type onlyReader struct {
        r io.Reader