Introduce method HistorySize.JSON()

Use it instead of `JSONString()`.

Author: mhagger

git-sizer.go

@@ -166,7 +166,7 @@ func mainImplementation() error {
 	}
 
 	if jsonOutput {
-		j, err := sizes.JSONString(historySize.Contents(), threshold, nameStyle)
+		j, err := historySize.JSON(threshold, nameStyle)
 		if err != nil {
 			return fmt.Errorf("could not convert %v to json: %s", historySize, err)
 		}

sizes/output.go

@@ -421,11 +421,12 @@ func (t *table) formatRow(
 	)
 }
 
-func JSONString(contents tableContents, threshold Threshold, nameStyle NameStyle) (string, error) {
+func (s HistorySize) JSON(threshold Threshold, nameStyle NameStyle) ([]byte, error) {
+	contents := s.Contents()
 	items := make(map[string]*item)
 	contents.CollectItems(items)
 	j, err := json.MarshalIndent(items, "", "    ")
-	return string(j), err
+	return j, err
 }
 
 func (s HistorySize) Contents() tableContents {