Fix label diff to respect --color flag

Author: kpengboy

internal/engine/apply/apply.go

@@ -129,7 +129,7 @@ func Diff(local, upstream GmailConfig, debugInfo bool, contextLines int, allowCo
 
 	if len(local.Labels) > 0 {
 		// LabelsDiff management opted-in
-		res.LabelsDiff, err = label.Diff(upstream.Labels, local.Labels)
+		res.LabelsDiff, err = label.Diff(upstream.Labels, local.Labels, allowColor)
 		if err != nil {
 			return res, fmt.Errorf("cannot compute labels diff: %w", err)
 		}

internal/engine/label/diff.go

@@ -14,11 +14,11 @@ import (
 //
 // To compute the diff, IDs are ignored, only the properties of the labels are
 // actually considered.
-func Diff(upstream, local Labels) (LabelsDiff, error) {
+func Diff(upstream, local Labels, allowColor bool) (LabelsDiff, error) {
 	sort.Sort(byName(upstream))
 	sort.Sort(byName(local))
 
-	res := LabelsDiff{}
+	res := LabelsDiff{AllowColor: allowColor}
 	i, j := 0, 0
 
 	for i < len(upstream) && j < len(local) {
@@ -63,9 +63,10 @@ func Diff(upstream, local Labels) (LabelsDiff, error) {
 
 // LabelsDiff contains the diff of two lists of labels.
 type LabelsDiff struct {
-	Modified []ModifiedLabel
-	Added    Labels
-	Removed  Labels
+	Modified   []ModifiedLabel
+	Added      Labels
+	Removed    Labels
+	AllowColor bool
 }
 
 // Empty returns true if the diff is empty.
@@ -103,7 +104,7 @@ func (d LabelsDiff) String() string {
 		FromFile: "Current",
 		ToFile:   "TO BE APPLIED",
 		Context:  3,
-		Color:    true,
+		Color:    d.AllowColor,
 	})
 	if err != nil {
 		// We can't get a diff apparently, let's make something up here