memoryobject: make blob reader seekable

Replace the bytes.Buffer with a bytes.Reader wrapped in a custom NopCloser, so that the extra reading methods are sill accessible.

1 files changed, 28 insertions, 0 deletions

diff --git a/plumbing/memory_test.go b/plumbing/memory_test.go
index 879ed37..2a141f4 100644
--- a/plumbing/memory_test.go
+++ b/plumbing/memory_test.go
@@ -1,6 +1,7 @@
 package plumbing
 
 import (
+	"io"
 	"io/ioutil"
 
 	. "gopkg.in/check.v1"
@@ -56,6 +57,33 @@ func (s *MemoryObjectSuite) TestReader(c *C) {
 	c.Assert(b, DeepEquals, []byte("foo"))
 }
 
+func (s *MemoryObjectSuite) TestSeekableReader(c *C) {
+	const pageSize = 4096
+	const payload = "foo"
+	content := make([]byte, pageSize+len(payload))
+	copy(content[pageSize:], []byte(payload))
+
+	o := &MemoryObject{cont: content}
+
+	reader, err := o.Reader()
+	c.Assert(err, IsNil)
+	defer func() { c.Assert(reader.Close(), IsNil) }()
+
+	rs, ok := reader.(io.ReadSeeker)
+	c.Assert(ok, Equals, true)
+
+	_, err = rs.Seek(pageSize, io.SeekStart)
+	c.Assert(err, IsNil)
+
+	b, err := ioutil.ReadAll(rs)
+	c.Assert(err, IsNil)
+	c.Assert(b, DeepEquals, []byte(payload))
+
+	// Check that our Reader isn't also accidentally writable
+	_, ok = reader.(io.WriteSeeker)
+	c.Assert(ok, Equals, false)
+}
+
 func (s *MemoryObjectSuite) TestWriter(c *C) {
 	o := &MemoryObject{}