Clarify paste tests

handler/paste/paster_test.go

@@ -121,7 +121,7 @@ func TestPipe(t *testing.T) {
 	pasteContents := []string{"hello", " pipe", ""}
 	errors := []error{nil, nil, io.EOF}
 
-	readCall := mockFile.On("Read", mock.Anything).Return(len(pasteContents[0]), nil)
+	readCall := mockFile.On("Read", mock.Anything)
 	readCall.Run(func(args mock.Arguments) {
 		buffer := args.Get(0).([]byte)
 		singlePasteContents := pasteContents[readCursor]
@@ -129,6 +129,7 @@ func TestPipe(t *testing.T) {
 		for i, char := range singlePasteContents {
 			buffer[i] = byte(char)
 		}
+		// Return the the values corresponding to readCursor
 		readCall.Return(len(singlePasteContents), errors[readCursor])
 
 		readCursor++