improve label matching checks and tests

Author: GrantBirki

internal/cmd/match_criteria.go

@@ -60,21 +60,39 @@ func branchMatchesCriteria(branch string) bool {
 }
 
 func labelsMatch(prLabels, ignoreLabels, selectLabels []string) bool {
-	for _, l := range ignoreLabels {
-		if i := slices.Index(prLabels, l); i != -1 {
-			return false
-		}
+	// If no ignoreLabels or selectLabels are specified, all labels pass this check
+	if len(ignoreLabels) == 0 && len(selectLabels) == 0 {
+		return true
 	}
 
-	for _, l := range selectLabels {
-		found := false
-		if i := slices.Index(prLabels, l); i != -1 {
-			break
+	// If the pull request contains any of the ignore labels, it doesn't match
+	if len(ignoreLabels) > 0 && len(prLabels) > 0 {
+		for _, l := range ignoreLabels {
+			if i := slices.Index(prLabels, l); i != -1 {
+				return false
+			}
 		}
+	}
 
-		if !found {
-			return false
+	// If ignoreLabels are specified without selectLabels and the pull request has no labels, it matches
+	if len(ignoreLabels) > 0 && len(selectLabels) == 0 && len(prLabels) == 0 {
+		return true
+	}
+
+	// If selectLabels are specified but the pull request has no labels, it doesn't match
+	if len(selectLabels) > 0 && len(prLabels) == 0 {
+		return false
+	}
+
+	// If the pull request contains any of the select labels, it matches
+	if len(selectLabels) > 0 && len(prLabels) > 0 {
+		for _, l := range selectLabels {
+			if i := slices.Index(prLabels, l); i != -1 {
+				return true
+			}
 		}
+		// If none of the select labels are found, it doesn't match
+		return false
 	}
 
 	return true

internal/cmd/match_criteria_test.go

@@ -44,6 +44,30 @@ func TestLabelsMatch(t *testing.T) {
 			selectLabels: []string{"a", "c"},
 			want:         true,
 		},
+		{
+			prLabels:     []string{},
+			ignoreLabels: []string{"b"},
+			selectLabels: []string{"a", "c"},
+			want:         false,
+		},
+		{
+			prLabels:     []string{},
+			ignoreLabels: []string{"b"},
+			selectLabels: []string{},
+			want:         true,
+		},
+		{
+			prLabels:     []string{},
+			ignoreLabels: []string{},
+			selectLabels: []string{"a"},
+			want:         false,
+		},
+		{
+			prLabels:     []string{},
+			ignoreLabels: []string{},
+			selectLabels: []string{},
+			want:         true,
+		},
 	}
 
 	for _, test := range tests {