Changing standard (Python) test discovery¶
Ignore paths during test collection¶
You can easily ignore certain test directories and modules during collection
by passing the --ignore=path
option on the cli. pytest
allows multiple
--ignore
options. Example:
tests/
├── example
│ ├── test_example_01.py
│ ├── test_example_02.py
│ └── test_example_03.py
├── foobar
│ ├── test_foobar_01.py
│ ├── test_foobar_02.py
│ └── test_foobar_03.py
└── hello
└── world
├── test_world_01.py
├── test_world_02.py
└── test_world_03.py
Now if you invoke pytest
with --ignore=tests/foobar/test_foobar_03.py --ignore=tests/hello/
,
you will see that pytest
only collects test-modules, which do not match the patterns specified:
========= test session starts ==========
platform darwin -- Python 2.7.10, pytest-2.8.2, py-1.4.30, pluggy-0.3.1
rootdir: $REGENDOC_TMPDIR, inifile:
collected 5 items
tests/example/test_example_01.py .
tests/example/test_example_02.py .
tests/example/test_example_03.py .
tests/foobar/test_foobar_01.py .
tests/foobar/test_foobar_02.py .
======= 5 passed in 0.02 seconds =======
Changing directory recursion¶
You can set the norecursedirs
option in an ini-file, for example your setup.cfg
in the project root directory:
# content of setup.cfg
[pytest]
norecursedirs = .svn _build tmp*
This would tell pytest
to not recurse into typical subversion or sphinx-build directories or into any tmp
prefixed directory.
Changing naming conventions¶
You can configure different naming conventions by setting
the python_files
, python_classes
and
python_functions
configuration options. Example:
# content of setup.cfg
# can also be defined in in tox.ini or pytest.ini file
[pytest]
python_files=check_*.py
python_classes=Check
python_functions=*_check
This would make pytest
look for tests in files that match the check_*
.py
glob-pattern, Check
prefixes in classes, and functions and methods
that match *_check
. For example, if we have:
# content of check_myapp.py
class CheckMyApp:
def simple_check(self):
pass
def complex_check(self):
pass
then the test collection looks like this:
$ py.test --collect-only
======= test session starts ========
platform linux -- Python 3.4.3, pytest-2.8.7, py-1.4.31, pluggy-0.3.1
rootdir: $REGENDOC_TMPDIR, inifile: setup.cfg
collected 2 items
<Module 'check_myapp.py'>
<Class 'CheckMyApp'>
<Instance '()'>
<Function 'simple_check'>
<Function 'complex_check'>
======= no tests ran in 0.12 seconds ========
Note
the python_functions
and python_classes
options has no effect
for unittest.TestCase
test discovery because pytest delegates
detection of test case methods to unittest code.
Interpreting cmdline arguments as Python packages¶
You can use the --pyargs
option to make pytest
try
interpreting arguments as python package names, deriving
their file system path and then running the test. For
example if you have unittest2 installed you can type:
py.test --pyargs unittest2.test.test_skipping -q
which would run the respective test module. Like with
other options, through an ini-file and the addopts
option you
can make this change more permanently:
# content of pytest.ini
[pytest]
addopts = --pyargs
Now a simple invocation of py.test NAME
will check
if NAME exists as an importable package/module and otherwise
treat it as a filesystem path.
Finding out what is collected¶
You can always peek at the collection tree without running tests like this:
. $ py.test --collect-only pythoncollection.py
======= test session starts ========
platform linux -- Python 3.4.3, pytest-2.8.7, py-1.4.31, pluggy-0.3.1
rootdir: $REGENDOC_TMPDIR, inifile: pytest.ini
collected 3 items
<Module 'CWD/pythoncollection.py'>
<Function 'test_function'>
<Class 'TestClass'>
<Instance '()'>
<Function 'test_method'>
<Function 'test_anothermethod'>
======= no tests ran in 0.12 seconds ========
customizing test collection to find all .py files¶
You can easily instruct pytest
to discover tests from every python file:
# content of pytest.ini
[pytest]
python_files = *.py
However, many projects will have a setup.py
which they don’t want to be imported. Moreover, there may files only importable by a specific python version.
For such cases you can dynamically define files to be ignored by listing
them in a conftest.py
file:
# content of conftest.py
import sys
collect_ignore = ["setup.py"]
if sys.version_info[0] > 2:
collect_ignore.append("pkg/module_py2.py")
And then if you have a module file like this:
# content of pkg/module_py2.py
def test_only_on_python2():
try:
assert 0
except Exception, e:
pass
and a setup.py dummy file like this:
# content of setup.py
0/0 # will raise exception if imported
then a pytest run on python2 will find the one test when run with a python2 interpreters and will leave out the setup.py file:
$ py.test --collect-only
======= test session starts ========
platform linux -- Python 3.4.3, pytest-2.8.7, py-1.4.31, pluggy-0.3.1
rootdir: $REGENDOC_TMPDIR, inifile: pytest.ini
collected 0 items
======= no tests ran in 0.12 seconds ========
If you run with a Python3 interpreter the moduled added through the conftest.py file will not be considered for test collection.