address comments

pkg/gitparse/gitparse_test.go

@@ -1307,7 +1307,7 @@ func TestMaxDiffSize(t *testing.T) {
 
 	select {
 	case commit := <-commitChan:
-		if commit.Diffs[0].Len() > parser.maxDiffSize+1024 {
+		if commit.Diffs[0].Len(ctx) > parser.maxDiffSize+1024 {
 			t.Errorf("diff did not match MaxDiffSize. Got: %d, expected (max): %d", commit.Diffs[0].Len(), parser.maxDiffSize+1024)
 		}
 	case <-ctx.Done():

pkg/writers/buffered_file_writer/bufferedfilewriter.go

@@ -63,7 +63,12 @@ func New(opts ...Option) *BufferedFileWriter {
 }
 
 // Len returns the number of bytes written to the buffer or file.
-func (w *BufferedFileWriter) Len() int { return int(w.size) }
+func (w *BufferedFileWriter) Len() (int, error) {
+	if w.state == writeOnly {
+		return 0, fmt.Errorf("BufferedFileWriter must be in read-only mode to get length")
+	}
+	return int(w.size), nil
+}
 
 // String returns all the data written to the buffer or file as a string or an empty string if there is an error.
 func (w *BufferedFileWriter) String() (string, error) {

pkg/writers/buffered_file_writer/bufferedfilewriter_test.go

@@ -116,7 +116,8 @@ func TestBufferedFileWriterLen(t *testing.T) {
 			_, err := writer.Write(context.Background(), tc.input)
 			assert.NoError(t, err)
 
-			length := writer.Len()
+			length, err := writer.Len()
+			assert.NoError(t, err)
 			assert.Equal(t, tc.expectedLen, length)
 		})
 	}