pkg: apply managed DNS mode in the macOS package

cmd/cli/intercept_mode_config_test.go

@@ -0,0 +1,38 @@
+package cli
+
+import (
+	"testing"
+
+	"github.com/Control-D-Inc/ctrld"
+)
+
+func TestUpdateConfigInterceptMode(t *testing.T) {
+	tests := []struct {
+		name        string
+		current     string
+		mode        string
+		want        string
+		wantUpdated bool
+	}{
+		{name: "empty flag preserves config", current: "dns", mode: "", want: "dns"},
+		{name: "dns is persisted", mode: "dns", want: "dns", wantUpdated: true},
+		{name: "hard is persisted", current: "dns", mode: "hard", want: "hard", wantUpdated: true},
+		{name: "off clears persisted mode", current: "dns", mode: "off", want: "", wantUpdated: true},
+		{name: "off is idempotent", mode: "off", want: ""},
+		{name: "invalid flag preserves config", current: "hard", mode: "invalid", want: "hard"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			cfg := &ctrld.Config{}
+			cfg.Service.InterceptMode = tc.current
+			updated := updateConfigInterceptMode(cfg, tc.mode)
+			if updated != tc.wantUpdated {
+				t.Fatalf("updateConfigInterceptMode() updated = %v, want %v", updated, tc.wantUpdated)
+			}
+			if cfg.Service.InterceptMode != tc.want {
+				t.Fatalf("service.intercept_mode = %q, want %q", cfg.Service.InterceptMode, tc.want)
+			}
+		})
+	}
+}