Testing Neutron
=============================================================

Overview
--------

Neutron relies on different types of testing to ensure its quality, as
described below.  In addition to in-tree testing, `Tempest`_ is
responsible for validating Neutron's integration with other OpenStack
components, and `Rally`_ is responsible for benchmarking.

.. _Tempest: http://docs.openstack.org/developer/tempest/
.. _Rally: http://rally.readthedocs.org/en/latest/

Unit Tests
~~~~~~~~~~

Unit tests (neutron/test/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 tree to make sure
any new changes don't break existing functionality.

Functional Tests
~~~~~~~~~~~~~~~~

Functional tests (neutron/tests/functional/) are intended to
validate actual system interaction.  Mocks should be used sparingly,
if at all.  Care should be taken to ensure that existing system
resources are not modified and that resources created in tests are
properly cleaned up.

API Tests
~~~~~~~~~

API tests (neutron/tests/api/) are intended to ensure the function
and stability of the Neutron API.  As much as possible, changes to
this path should not be made at the same time as changes to the code
to limit the potential for introducing backwards-incompatible changes.

Since API tests need to be able to target a deployed Neutron daemon
that is not necessarily test-managed, they should not depend on
controlling the runtime configuration of the target daemon.  API tests
should be black-box - no assumptions should be made about
implementation.  Only the contract defined by Neutron's REST API
should be validated, and all interaction with the daemon should be via
a REST client.

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.

Structure of the unit test tree
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The structure of the unit test tree should match the structure of the
code tree, e.g. ::

 - target module: neutron.agent.utils

 - test module: neutron.tests.unit.agent.test_utils

Unit test modules should have the same path under neutron/tests/unit/
as the module they target has under neutron/, and their name should be
the name of the target module prefixed by 'test_'.  This requirement
is intended to make it easier for developers to find the unit tests
for a given module.

Similarly, when a test module targets a package, that module's name
should be the name of the package prefixed by 'test_' with the same
path as when a test targets a module, e.g. ::

 - target package: neutron.ipam

 - test module: neutron.tests.unit.test_ipam

The following command can be used to validate whether the unit test
tree is structured according to the above requirements: ::

    ./tools/check_unit_test_structure.sh

Where appropriate, exceptions can be added to the above script.  If
code is not part of the neutron namespace, for example, it's probably
reasonable to exclude their unit tests from the check.

Virtual environments
~~~~~~~~~~~~~~~~~~~~

Testing OpenStack projects, including Neutron, is made easier with `DevStack <https://git.openstack.org/cgit/openstack-dev/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.

 .. note::

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


Running tests
-------------

There are three mechanisms for running tests: run_tests.sh, tox,
and nose2. 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 `nose2`
~~~~~~~~~~~~

You can use `nose2`_ to run individual tests, as well as use for debugging
portions of your code::

    source .venv/bin/activate
    pip install nose2
    nose2

There are disadvantages to running nose2 - 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.

It is also possible to use nose2's predecessor, `nose`_, to run the tests::

    source .venv/bin/activate
    pip install nose
    nosetests

nose has one additional disadvantage over nose2 - it does not
understand the `load_tests protocol`_ introduced in Python 2.7.  This
limitation will result in errors being reported for modules that
depend on load_tests (usually due to use of `testscenarios`_).

.. _nose2: http://nose2.readthedocs.org/en/latest/index.html
.. _nose: https://nose.readthedocs.org/en/latest/index.html
.. _load_tests protocol: https://docs.python.org/2/library/unittest.html#load-tests-protocol
.. _testscenarios: https://pypi.python.org/pypi/testscenarios/

With `tox`
~~~~~~~~~~

Neutron, 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 (2.6, 2.7, 3.3, etc).

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

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:

  https://wiki.openstack.org/wiki/Testr

.. _Testr: https://wiki.openstack.org/wiki/Testr
.. _tox: http://tox.readthedocs.org/en/latest/
.. _virtualenvs: https://pypi.python.org/pypi/virtualenv

PEP8 and Unit Tests
===================

Running pep8 and unit tests is as easy as executing this in the root
directory of the Neutron source code::

    tox

To run only pep8::

    tox -e pep8

To run only the unit tests::

    tox -e py27

Functional Tests
================

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

    tox -e functional

To run all the functional tests, including those requiring sudo
privileges and system-specific dependencies, the procedure defined by
tools/configure_for_func_testing.sh should be followed.

IMPORTANT: configure_for_func_testing.sh relies on devstack to perform
extensive modification to the underlying host.  Execution of the
script requires sudo privileges and it is recommended that the
following commands be invoked only on a clean and disposeable VM.  A
VM that has had devstack previously installed on it is also fine. ::

    git clone https://git.openstack.org/openstack-dev/devstack ../devstack
    ./tools/configure_for_func_testing.sh ../devstack -i
    tox -e dsvm-functional

The '-i' option is optional and instructs the script to use devstack
to install and configure all of Neutron's package dependencies.  It is
not necessary to provide this option if devstack has already been used
to deploy Neutron to the target host.

Fullstack Tests
===============

To run all the full-stack tests, you may use: ::

    tox -e dsvm-fullstack

Since full-stack tests often require the same resources and
dependencies as the functional tests, using the configuration script
tools/configure_for_func_testing.sh is advised (as described above).
When running full-stack tests on a clean VM for the first time, we
advise to run ./stack.sh successfully to make sure all Neutron's
dependencies are met.  Also note that in order to preserve resources
on the gate, running the dsvm-functional suite will also run all
full-stack tests (and a new worker won't be assigned specifically for
dsvm-fullstack).

API Tests
=========

To run the api tests, deploy tempest and neutron with devstack and
then run the following command: ::

    tox -e api

If tempest.conf cannot be found at the default location used by
devstack (/opt/stack/tempest/etc) it may be necessary to set
TEMPEST_CONFIG_DIR before invoking tox: ::

    export TEMPEST_CONFIG_DIR=[path to dir containing tempest.conf]
    tox -e api


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 JSONV2TestCase tests from
neutron/tests/unit/test_api_v2.py::

      $ ./run_tests.sh neutron.tests.unit.test_api_v2.JSONV2TestCase

or::

      $ tox -e py27 neutron.tests.unit.test_api_v2.JSONV2TestCase

Adding more tests
~~~~~~~~~~~~~~~~~

Neutron 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

Debugging
---------

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 neutron 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]

References
==========

.. [#pudb] PUDB debugger:
   https://pypi.python.org/pypi/pudb
