emulator: tests: add license and header include guards.

Author: marete

google/cloud/bigtable/emulator/test_util.h

@@ -1,3 +1,20 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_BIGTABLE_EMULATOR_TEST_UTIL_H
+#define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_BIGTABLE_EMULATOR_TEST_UTIL_H
+
 #include "google/cloud/bigtable/emulator/table.h"
 #include <memory>
 #include <string>
@@ -26,3 +43,5 @@ StatusOr<std::shared_ptr<Table>> CreateTable(
 }  // namespace bigtable
 }  // namespace cloud
 }  // namespace google
+
+#endif // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_BIGTABLE_EMULATOR_TEST_UTIL_H