Document running tests on catkin packages

[paulbovbel]

Doing a bit of experimenting, I've found that running test on catkin packages isn't quite as straightforward as colcon build && colcon test. It's not immediately obvious, but one has to run:

colcon build --cmake-target tests
colcon test

...as extracted from ros-infrastructure/ros_buildfarm#548,

---

I'm guessing this is my fault, but I've found that when I attach a DEPENDENCY to catkin_add_nosetests such as when using catkin_virtualenv (https://github.com/paulbovbel/test_meta/blob/master/CMakeLists.txt#L52), I have to run the following to get all tests to pass:

colcon build
colcon build --cmake-target tests
colcon test

Even though it looks like the ${PROJECT_NAME}_generate_virtualenv should be getting hooked in via the underlying catkin mechanisms.

[dirk-thomas]

In catkin packages test targets are usually created with the EXCLUDE_FROM_ALL flag. Therefore they are not being built by a normal cmake --build invocation. To the second snippet (colcon build, colcon build --cmake-target tests, colcon test) is the right "generic" approach.

Can you create a pull request to update the documentation accordingly?

[paulbovbel]

Done #30

Although I wonder if for consistency's sake, it would make sense to suppress EXCLUDE_FROM_ALL behaviour when building from ROS via colcon.

[dirk-thomas]

it would make sense to suppress EXCLUDE_FROM_ALL behaviour when building from ROS via colcon

I don't think there is (currently?) a way to override that from the "outside". The argument is hard coded in the CMake code (e.g. the catkin function to add tests) but potentially also in the package specific CMake code. If you can imagine a way I would be happy to consider it.