feat: comprehensive test suite (Phase 4.2) (#12)

internal/dns/resolver_test.go

@@ -455,3 +455,22 @@ func TestBasicResolver(t *testing.T) {
 		t.Fatal("BasicResolver does not implement Resolver interface")
 	}
 }
+
+// TestBasicResolverQueryIntegration calls Query via the BasicResolver against
+// the local system resolver. Skipped when no local resolver is reachable.
+func TestBasicResolverQueryIntegration(t *testing.T) {
+r := NewBasicResolver()
+server := net.ParseIP("127.0.0.1")
+ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+defer cancel()
+
+// Cover BasicResolver.Query; skip if 127.0.0.1:53 is not available.
+msg, err := r.Query(ctx, server, ".", TypeNS, nil)
+if err != nil {
+t.Logf("skipping (local resolver unavailable): %v", err)
+t.Skip()
+}
+if msg == nil {
+t.Fatal("expected non-nil response from BasicResolver.Query")
+}
+}