Process isolation in tests

[asmodehn]

Currently the pyros tests are testing integration with sample ROS systems.

While it is very useful to ensure everything is working as expected (versus requiring specs/mock during unittest & have integration tests at a later stage), it triggers a conflict between :

• ROS is inherently multiprocess.
• Python Test Framework are by default "mono process", loading only one interpreter to run all tests.

Possible solutions are :

• launch test separately (current workaround)
• http://stackoverflow.com/questions/11802316/nose2-vs-py-test-with-isolated-processes => moving to pytest + https://pypi.python.org/pypi/pytest-xdist
• start using https://github.com/dmccombs/nosepipe ( would be good for testing ROS nodes anyway, even with basic catkin )
• have specs based unit tests + leave integration test for a later stage...

[asmodehn]

After chatting with @stonier, another possible solution might be to use roslaunch or rosunit/rostest to launch a ROS node in its own subprocess. We need to investigate if this is doable in such cases.

[asmodehn]

Also for testing in pyros we usually :

• need to init_node to communicate via topics
• need to run a custom test with ros_interface (which node_init by itself).

It is not yet clear if :

• rostest/rosunit would support this usecase
• we should always subprocess from inside the test code
• we are better off using nosepipe to subprocess all tests by default.
• we are better off moving to py.test and use xdist -n1 --boxed but careful.

For now, working around it by calling the tests separately and moving on...