base: enable test in cmake based build

ortools/base/CMakeLists.txt

@@ -40,3 +40,22 @@ target_link_libraries(${NAME} PRIVATE
   protobuf::libprotobuf
   ${PROJECT_NAMESPACE}::ortools_proto)
 #add_library(${PROJECT_NAMESPACE}::base ALIAS ${NAME})
+
+if(BUILD_TESTING)
+  file(GLOB _TEST_SRCS "*_test.cc")
+  foreach(_FULL_FILE_NAME IN LISTS _TEST_SRCS)
+    get_filename_component(_NAME ${_FULL_FILE_NAME} NAME_WE)
+    get_filename_component(_FILE_NAME ${_FULL_FILE_NAME} NAME)
+    ortools_cxx_test(
+      NAME
+        base_${_NAME}
+      SOURCES
+        ${_FILE_NAME}
+      LINK_LIBRARIES
+        benchmark::benchmark
+        GTest::gtest
+        GTest::gtest_main
+        GTest::gmock
+    )
+  endforeach()
+endif()