[dev.link] all: merge branch 'master' into dev.link

Change-Id: Ic66b5138f3ecd9e9a48d7ab05782297c06e4a5b5

1 files changed, 14 insertions, 0 deletions

diff --git a/src/testing/iotest/reader.go b/src/testing/iotest/reader.go
index 8d82018fd6..bc2f72a911 100644
--- a/src/testing/iotest/reader.go
+++ b/src/testing/iotest/reader.go
@@ -68,6 +68,7 @@ func (r *dataErrReader) Read(p []byte) (n int, err error) {
 	return
 }
 
+// ErrTimeout is a fake timeout error.
 var ErrTimeout = errors.New("timeout")
 
 // TimeoutReader returns ErrTimeout on the second read
@@ -86,3 +87,16 @@ func (r *timeoutReader) Read(p []byte) (int, error) {
 	}
 	return r.r.Read(p)
 }
+
+// ErrReader returns an io.Reader that returns 0, err from all Read calls.
+func ErrReader(err error) io.Reader {
+	return &alwaysErrReader{err: err}
+}
+
+type alwaysErrReader struct {
+	err error
+}
+
+func (aer *alwaysErrReader) Read(p []byte) (int, error) {
+	return 0, aer.err
+}