chore: Memory efficient string-join (#16)

Use idiomatic golang string-join. More memory efficient.

Author: hughdbrown

internal/oauth/oauth.go

@@ -334,14 +334,7 @@ func (m *Manager) tokenPath(email string) string {
 
 // scopesToString joins scopes with spaces.
 func scopesToString(scopes []string) string {
-	result := ""
-	for i, s := range scopes {
-		if i > 0 {
-			result += " "
-		}
-		result += s
-	}
-	return result
+	return strings.Join(scopes, " ")
 }
 
 // openBrowser opens the default browser to the given URL.

internal/oauth/oauth_test.go

@@ -0,0 +1,43 @@
+package oauth
+
+import (
+	"testing"
+)
+
+func TestScopesToString(t *testing.T) {
+	tests := []struct {
+		name   string
+		scopes []string
+		want   string
+	}{
+		{
+			name:   "empty scopes",
+			scopes: []string{},
+			want:   "",
+		},
+		{
+			name:   "single scope",
+			scopes: []string{"https://www.googleapis.com/auth/gmail.readonly"},
+			want:   "https://www.googleapis.com/auth/gmail.readonly",
+		},
+		{
+			name:   "multiple scopes",
+			scopes: []string{"https://www.googleapis.com/auth/gmail.readonly", "https://www.googleapis.com/auth/gmail.modify"},
+			want:   "https://www.googleapis.com/auth/gmail.readonly https://www.googleapis.com/auth/gmail.modify",
+		},
+		{
+			name:   "three scopes",
+			scopes: []string{"scope1", "scope2", "scope3"},
+			want:   "scope1 scope2 scope3",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := scopesToString(tt.scopes)
+			if got != tt.want {
+				t.Errorf("scopesToString() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}