Quickly running a single OpenStack Nova test

Here’s how we usually run a single test

dims@dims-mac:~/openstack/nova$ time tox -e py27 nova.tests.unit.test_versions
py27 develop-inst-noop: /Users/dims/openstack/nova
py27 runtests: PYTHONHASHSEED='0'
py27 runtests: commands[0] | find . -type f -name *.pyc -delete
py27 runtests: commands[1] | bash tools/pretty_tox.sh nova.tests.unit.test_versions
{1} nova.tests.unit.test_versions.VersionTestCase.test_version_string_with_package_is_good [0.180036s] ... ok
{0} nova.tests.unit.test_versions.VersionTestCase.test_release_file [0.184115s] ... ok

======
Totals
======
Ran: 2 tests in 13.0000 sec.
 - Passed: 2
 - Skipped: 0
 - Failed: 0
Sum of execute time for each test: 0.3642 sec.

==============
Worker Balance
==============
 - Worker 0 (1 tests) => 0:00:00.184115s
 - Worker 1 (1 tests) => 0:00:00.180036s
________________________________________________________________________________________________________________________ summary _________________________________________________________________________________________________________________________
  py27: commands succeeded
  congratulations 🙂

real	0m14.452s
user	0m16.392s
sys	0m2.354s

Sometimes the usual way is not very helpful, especially when you are working on some new code and say running into issues importing code. Then, here’s what you do.

First, activate the py27 virtualenv

dims@dims-mac:~/openstack/nova$ . .tox/py27/bin/activate

Then use testtools

(py27)dims@dims-mac:~/openstack/nova$ python -m testtools.run nova.tests.unit.test_versions
Tests running...

Ran 2 tests in 0.090s
OK

Or you can install pytest

(py27)dims@dims-mac:~/openstack/nova$ pip install pytest
Collecting pytest
  Downloading pytest-2.6.4.tar.gz (512kB)
    100% |################################| 516kB 877kB/s
Collecting py>=1.4.25 (from pytest)
  Downloading py-1.4.26.tar.gz (190kB)
    100% |################################| 192kB 4.3MB/s
Installing collected packages: py, pytest
  Running setup.py install for py
  Running setup.py install for pytest
    Installing py.test-2.7 script to /Users/dims/openstack/nova/.tox/py27/bin
    Installing py.test script to /Users/dims/openstack/nova/.tox/py27/bin
Successfully installed py-1.4.26 pytest-2.6.4

And then run the same test using py.test

(py27)dims@dims-mac:~/openstack/nova$ find . -name py.test
./.tox/py27/bin/py.test

(py27)dims@dims-mac:~/openstack/nova$ .tox/py27/bin/py.test -svx nova/tests/unit/test_versions.py
================================================================================================================== test session starts ===================================================================================================================
platform darwin -- Python 2.7.8 -- py-1.4.26 -- pytest-2.6.4 -- /Users/dims/openstack/nova/.tox/py27/bin/python2.7
collected 2 items

nova/tests/unit/test_versions.py::VersionTestCase::test_release_file PASSED
nova/tests/unit/test_versions.py::VersionTestCase::test_version_string_with_package_is_good PASSED

================================================================================================================ 2 passed in 1.69 seconds ================================================================================================================

These tips are based on the openstack-dev mailing list discussion:
http://openstack.markmail.org/thread/wetxcnhuq6b7auhn