add CommentConverterFunc to simplify injection of custom converters

backend/app/store/formatter.go

@@ -19,6 +19,14 @@ type CommentConverter interface {
 	Convert(text string) string
 }
 
+// CommentConverterFunc functional struct implementing CommentConverter
+type CommentConverterFunc func(text string) string
+
+// Convert calls func for given text
+func (f CommentConverterFunc) Convert(text string) string {
+	return f(text)
+}
+
 // NewCommentFormatter makes CommentFormatter
 func NewCommentFormatter(converters ...CommentConverter) *CommentFormatter {
 	return &CommentFormatter{converters: converters}

backend/app/store/formatter_test.go

@@ -33,6 +33,12 @@ func TestFormatter_FormatTextNoConvertor(t *testing.T) {
 	assert.Equal(t, "<p>12345</p>\n", f.FormatText("12345"))
 }
 
+func TestFormatter_FormatTextConvertorFunc(t *testing.T) {
+	fn := CommentConverterFunc(func(text string) string { return "zz!" + text })
+	f := NewCommentFormatter(fn)
+	assert.Equal(t, "zz!<p>12345</p>\n", f.FormatText("12345"))
+}
+
 func TestFormatter_FormatComment(t *testing.T) {
 	comment := Comment{
 		Text:      "blah\n\nxyz",