formats: objfile idomatic reader/writer

1 files changed, 31 insertions, 20 deletions

diff --git a/formats/objfile/writer_test.go b/formats/objfile/writer_test.go
index ab5a5bf..18bba79 100644
--- a/formats/objfile/writer_test.go
+++ b/formats/objfile/writer_test.go
@@ -16,54 +16,65 @@ var _ = Suite(&SuiteWriter{})
 
 func (s *SuiteWriter) TestWriteObjfile(c *C) {
 	for k, fixture := range objfileFixtures {
+		buffer := bytes.NewBuffer(nil)
+
 		com := fmt.Sprintf("test %d: ", k)
 		hash := core.NewHash(fixture.hash)
 		content, _ := base64.StdEncoding.DecodeString(fixture.content)
-		buffer := new(bytes.Buffer)
 
 		// Write the data out to the buffer
-		testWriter(c, buffer, hash, fixture.t, content, com)
+		testWriter(c, buffer, hash, fixture.t, content)
 
 		// Read the data back in from the buffer to be sure it matches
 		testReader(c, buffer, hash, fixture.t, content, com)
 	}
 }
 
-func testWriter(c *C, dest io.Writer, hash core.Hash, typ core.ObjectType, content []byte, com string) {
-	length := int64(len(content))
-	w, err := NewWriter(dest, typ, length)
+func testWriter(c *C, dest io.Writer, hash core.Hash, t core.ObjectType, content []byte) {
+	size := int64(len(content))
+	w := NewWriter(dest)
+
+	err := w.WriteHeader(t, size)
 	c.Assert(err, IsNil)
-	c.Assert(w.Type(), Equals, typ)
-	c.Assert(w.Size(), Equals, length)
+
 	written, err := io.Copy(w, bytes.NewReader(content))
 	c.Assert(err, IsNil)
-	c.Assert(written, Equals, length)
-	c.Assert(w.Size(), Equals, int64(len(content)))
-	c.Assert(w.Hash(), Equals, hash) // Test Hash() before close
+	c.Assert(written, Equals, size)
+
+	c.Assert(w.Hash(), Equals, hash)
 	c.Assert(w.Close(), IsNil)
-	c.Assert(w.Hash(), Equals, hash) // Test Hash() after close
-	_, err = w.Write([]byte{1})
-	c.Assert(err, Equals, ErrClosed)
 }
 
 func (s *SuiteWriter) TestWriteOverflow(c *C) {
-	w, err := NewWriter(new(bytes.Buffer), core.BlobObject, 8)
+	buf := bytes.NewBuffer(nil)
+	w := NewWriter(buf)
+
+	err := w.WriteHeader(core.BlobObject, 8)
 	c.Assert(err, IsNil)
-	_, err = w.Write([]byte("1234"))
+
+	n, err := w.Write([]byte("1234"))
 	c.Assert(err, IsNil)
-	_, err = w.Write([]byte("56789"))
+	c.Assert(n, Equals, 4)
+
+	n, err = w.Write([]byte("56789"))
 	c.Assert(err, Equals, ErrOverflow)
+	c.Assert(n, Equals, 4)
 }
 
 func (s *SuiteWriter) TestNewWriterInvalidType(c *C) {
-	var t core.ObjectType
-	_, err := NewWriter(new(bytes.Buffer), t, 8)
+	buf := bytes.NewBuffer(nil)
+	w := NewWriter(buf)
+
+	err := w.WriteHeader(core.InvalidObject, 8)
 	c.Assert(err, Equals, core.ErrInvalidType)
 }
 
 func (s *SuiteWriter) TestNewWriterInvalidSize(c *C) {
-	_, err := NewWriter(new(bytes.Buffer), core.BlobObject, -1)
+	buf := bytes.NewBuffer(nil)
+	w := NewWriter(buf)
+
+	err := w.WriteHeader(core.BlobObject, -1)
 	c.Assert(err, Equals, ErrNegativeSize)
-	_, err = NewWriter(new(bytes.Buffer), core.BlobObject, -1651860)
+	err = w.WriteHeader(core.BlobObject, -1651860)
 	c.Assert(err, Equals, ErrNegativeSize)
 }