add CMake function ament_add_test_label() (#240)

Signed-off-by: Dirk Thomas <dirk-thomas@users.noreply.github.com>
Signed-off-by: Jose Luis Rivero <jrivero@osrfoundation.org>

ament_cmake_test/ament_cmake_test-extras.cmake

@@ -39,3 +39,4 @@ endif()
 find_package(ament_cmake_core QUIET REQUIRED)
 
 include("${ament_cmake_test_DIR}/ament_add_test.cmake")
+include("${ament_cmake_test_DIR}/ament_add_test_label.cmake")

ament_cmake_test/cmake/ament_add_test_label.cmake

@@ -0,0 +1,29 @@
+# Copyright 2020 Open Source Robotics Foundation, Inc.
+#
+# 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
+#
+#     http://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.
+
+#
+# Add text labels to the LABELS property of a test.
+#
+# :param testname: the name of the test
+# :type testname: string
+# :param ARGN: a list of labels
+# :type ARGN: list of strings
+#
+# @public
+#
+function(ament_add_test_label testname)
+  get_test_property(${testname} LABELS labels)
+  list(APPEND labels ${ARGN})
+  set_tests_properties(${testname} PROPERTIES LABELS "${labels}")
+endfunction()