6.1 KiB

Testing VMware-NSX


The unit tests (vmware_nsx/tests/unit/) are meant to cover as much code as possible and should be executed without the service running. They are designed to test the various pieces of the neutron and VMware NSX tree to make sure any new changes don't break existing functionality.

Development process

It is expected that any new changes that are proposed for merge come with tests for that feature or code area. Ideally any bugs fixes that are submitted also have tests to prove that they stay fixed! In addition, before proposing for merge, all of the current tests should be passing.

Virtual environments

Testing OpenStack projects, including Neutron, is made easier with DevStack.

Create a machine (such as a VM or Vagrant box) running a distribution supported by DevStack and install DevStack there. For example, there is a Vagrant script for DevStack at https://github.com/bcwaldon/vagrant_devstack.


If you prefer not to use DevStack, you can still check out source code on your local machine and develop from there.

Running unit tests

There are three mechanisms for running tests: run_tests.sh, tox, and nose. Before submitting a patch for review you should always ensure all test pass; a tox run is triggered by the jenkins gate executed on gerrit for each patch pushed for review.

With these mechanisms you can either run the tests in the standard environment or create a virtual environment to run them in.

By default after running all of the tests, any pep8 errors found in the tree will be reported.

With run_tests.sh

You can use the run_tests.sh script in the root source directory to execute tests in a virtualenv:

./run_tests -V

With nose

You can use nose to run individual tests, as well as use for debugging portions of your code:

. .venv/bin/activate
pip install nose

There are disadvantages to running Nose - the tests are run sequentially, so race condition bugs will not be triggered, and the full test suite will take significantly longer than tox & testr. The upside is that testr has some rough edges when it comes to diagnosing errors and failures, and there is no easy way to set a breakpoint in the Neutron code, and enter an interactive debugging session while using testr.

With tox

VMware NSX, like other OpenStack projects, uses tox for managing the virtual environments for running test cases. It uses Testr for managing the running of the test cases.

Tox handles the creation of a series of virtualenvs that target specific versions of Python.

Testr handles the parallel execution of series of test cases as well as the tracking of long-running tests and other things.

Running unit tests is as easy as executing this in the root directory of the Neutron source code:


To run functional tests that do not require sudo privileges or specific-system dependencies:

tox -e functional

To run all the functional tests in an environment that has been configured by devstack to support sudo and system-specific dependencies:

tox -e dsvm-functional

For more information on the standard Tox-based test infrastructure used by OpenStack and how to do some common test/debugging procedures with Testr, see this wiki page:


Running individual tests

For running individual test modules or cases, you just need to pass the dot-separated path to the module you want as an argument to it.

For executing a specific test case, specify the name of the test case class separating it from the module path with a colon.

For example, the following would run only the TestSubnetsV2 tests from vmware_nsx/tests/unit/nsx_v/test_plugin.py:

$ ./run_tests.sh vmware_nsx.tests.unit.nsx_v.test_plugin.TestSubnetsV2


$ tox -e py37 vmware_nsx.tests.unit.nsx_v.test_plugin.TestSubnetsV2

Adding more tests

VMware NSX has a fast growing code base and there is plenty of areas that need to be covered by unit and functional tests.

To get a grasp of the areas where tests are needed, you can check current coverage by running:

$ ./run_tests.sh -c


By default, calls to pdb.set_trace() will be ignored when tests are run. For pdb statements to work, invoke run_tests as follows:

$ ./run_tests.sh -d [test module path]

It's possible to debug tests in a tox environment:

$ tox -e venv -- python -m testtools.run [test module path]

Tox-created virtual environments (venv's) can also be activated after a tox run and reused for debugging:

$ tox -e venv
$ . .tox/venv/bin/activate
$ python -m testtools.run [test module path]

Tox packages and installs the vmware-nsx source tree in a given venv on every invocation, but if modifications need to be made between invocation (e.g. adding more pdb statements), it is recommended that the source tree be installed in the venv in editable mode:

# run this only after activating the venv
$ pip install --editable .

Editable mode ensures that changes made to the source tree are automatically reflected in the venv, and that such changes are not overwritten during the next tox run.

Post-mortem debugging

Setting OS_POST_MORTEM_DEBUGGER in the shell environment will ensure that the debugger .post_mortem() method will be invoked on test failure:

$ OS_POST_MORTEM_DEBUGGER=pdb ./run_tests.sh -d [test module path]

Supported debuggers are pdb, and pudb. Pudb is full-screen, console-based visual debugger for Python which let you inspect variables, the stack, and breakpoints in a very visual way, keeping a high degree of compatibility with pdb:

$ ./.venv/bin/pip install pudb

$ OS_POST_MORTEM_DEBUGGER=pudb ./run_tests.sh -d [test module path]