How to best call catkin_add_gtest and add_rostest_gtest separately?

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I'm trying to test ROS code at two different levels (calling catkin_add_gtest and add_rostest_gtest separately), and I haven't found documentation on exactly how to do what I'm hoping to do.

Essentially, I have src/library.cpp that I'd want to run gtest tests on through test/test_library.cpp. This should test low-level functionality - just the methods and functions defined in library.cpp, without any need of having a node running or publishing/subscribing.

I'd also like to run a full-fledged node-level test, running multiple nodes through rostest (defined in a test/test_node.test file), spun up through a gtest node defined in test/test_node.cpp.

The problem I'm facing is that if I run catkin run_tests package_name, this runs both the catkin_add_gtest and add_rostest_gtest targets. I'd like to use some command to run only one or the other, not both. How might I do that?

See example CMakeLists.txt below.

# CMakeLists.txt
...
add_library(library src/library.cpp )
target_link_libraries(library ${catkin_LIBRARIES})

if(CATKIN_ENABLE_TESTING)

  if(TARGET run_library_test) # can I do this?
    find_package(catkin REQUIRED rostest)
    catkin_add_gtest(test_library test/test_library.cpp)
    target_link_libraries(test_library library ${catkin_LIBRARIES})
  endif() # run_library_test

  if(TARGET run_node_test) # can I do this?
    find_package(catkin REQUIRED rostest)
    add_rostest_gtest(test_node test/test_node.test test/test_node.cpp)
    target_link_libraries(test_node library ${catkin_LIBRARIES})
  endif() # run_node_test

endif() # CATKIN_ENABLE_TESTING