PYTEST(1) pytest PYTEST(1)NAME
pytest - pytest usage
CALLING PYTEST THROUGH PYTHON -M PYTEST
New in version 2.0.
You can invoke testing through the Python interpreter from the command
line:
python -m pytest [...]
This is almost equivalent to invoking the command line script pytest
[...] directly, except that Python will also add the current directory
to sys.path.
POSSIBLE EXIT CODES
Running pytest can result in six different exit codes:
Exit code 0
All tests were collected and passed successfully
Exit code 1
Tests were collected and run but some of the tests failed
Exit code 2
Test execution was interrupted by the user
Exit code 3
Internal error happened while executing tests
Exit code 4
pytest command line usage error
Exit code 5
No tests were collected
GETTING HELP ON VERSION, OPTION NAMES, ENVIRONMENT VARIABLES
pytest --version # shows where pytest was imported from
pytest --fixtures # show available builtin function arguments
pytest -h | --help # show help on command line and config file options
STOPPING AFTER THE FIRST (OR N) FAILURES
To stop the testing process after the first (N) failures:
pytest -x # stop after first failure
pytest --maxfail=2 # stop after two failures
SPECIFYING TESTS / SELECTING TESTS
Pytest supports several ways to run and select tests from the com‐
mand-line.
Run tests in a module
pytest test_mod.py
Run tests in a directory
pytest testing/
Run tests by keyword expressions
pytest -k "MyClass and not method"
This will run tests which contain names that match the given string
expression, which can include Python operators that use filenames,
class names and function names as variables. The example above will
run TestMyClass.test_something but not TestMyClass.test_method_simple.
Run tests by node ids
Each collected test is assigned a unique nodeid which consist of the
module filename followed by specifiers like class names, function names
and parameters from parametrization, separated by :: characters.
To run a specific test within a module:
pytest test_mod.py::test_func
Another example specifying a test method in the command line:
pytest test_mod.py::TestClass::test_method
Run tests by marker expressions
pytest -m slow
Will run all tests which are decorated with the @pytest.mark.slow deco‐
rator.
For more information see marks.
Run tests from packages
pytest --pyargs pkg.testing
This will import pkg.testing and use its filesystem location to find
and run tests from.
MODIFYING PYTHON TRACEBACK PRINTING
Examples for modifying traceback printing:
pytest --showlocals # show local variables in tracebacks
pytest -l # show local variables (shortcut)
pytest --tb=auto # (default) 'long' tracebacks for the first and last
# entry, but 'short' style for the other entries
pytest --tb=long # exhaustive, informative traceback formatting
pytest --tb=short # shorter traceback format
pytest --tb=line # only one line per failure
pytest --tb=native # Python standard library formatting
pytest --tb=no # no traceback at all
The --full-trace causes very long traces to be printed on error (longer
than --tb=long). It also ensures that a stack trace is printed on Key‐
boardInterrupt (Ctrl+C). This is very useful if the tests are taking
too long and you interrupt them with Ctrl+C to find out where the tests
are hanging. By default no output will be shown (because KeyboardInter‐
rupt is caught by pytest). By using this option you make sure a trace
is shown.
DROPPING TO PDB (PYTHON DEBUGGER) ON FAILURES
Python comes with a builtin Python debugger called PDB. pytest allows
one to drop into the PDB prompt via a command line option:
pytest --pdb
This will invoke the Python debugger on every failure. Often you might
only want to do this for the first failing test to understand a certain
failure situation:
pytest -x --pdb # drop to PDB on first failure, then end test session
pytest --pdb --maxfail=3 # drop to PDB for first three failures
Note that on any failure the exception information is stored on
sys.last_value, sys.last_type and sys.last_traceback. In interactive
use, this allows one to drop into postmortem debugging with any debug
tool. One can also manually access the exception information, for exam‐
ple:
>>> import sys
>>> sys.last_traceback.tb_lineno
42
>>> sys.last_value
AssertionError('assert result == "ok"',)
SETTING BREAKPOINTS
To set a breakpoint in your code use the native Python import
pdb;pdb.set_trace() call in your code and pytest automatically disables
its output capture for that test:
· Output capture in other tests is not affected.
· Any prior test output that has already been captured and will be pro‐
cessed as such.
· Any later output produced within the same test will not be captured
and will instead get sent directly to sys.stdout. Note that this
holds true even for test output occurring after you exit the interac‐
tive PDB tracing session and continue with the regular test run.
PROFILING TEST EXECUTION DURATION
To get a list of the slowest 10 test durations:
pytest --durations=10
CREATING JUNITXML FORMAT FILES
To create result files which can be read by Jenkins or other Continuous
integration servers, use this invocation:
pytest --junitxml=path
to create an XML file at path.
New in version 3.1.
To set the name of the root test suite xml item, you can configure the
junit_suite_name option in your config file:
[pytest]
junit_suite_name = my_suite
record_xml_property
New in version 2.8.
If you want to log additional information for a test, you can use the
record_xml_property fixture:
def test_function(record_xml_property):
record_xml_property("example_key", 1)
assert 0
This will add an extra property example_key="1" to the generated test‐
case tag:
<testcase classname="test_function" file="test_function.py" line="0" name="test_function" time="0.0009">
<properties>
<property name="example_key" value="1" />
</properties>
</testcase>
WARNING:
record_xml_property is an experimental feature, and its interface
might be replaced by something more powerful and general in future
versions. The functionality per-se will be kept, however.
Currently it does not work when used with the pytest-xdist plugin.
Also please note that using this feature will break any schema veri‐
fication. This might be a problem when used with some CI servers.
LogXML: add_global_property
New in version 3.0.
If you want to add a properties node in the testsuite level, which may
contains properties that are relevant to all testcases you can use
LogXML.add_global_properties
import pytest
@pytest.fixture(scope="session")
def log_global_env_facts(f):
if pytest.config.pluginmanager.hasplugin('junitxml'):
my_junit = getattr(pytest.config, '_xml', None)
my_junit.add_global_property('ARCH', 'PPC')
my_junit.add_global_property('STORAGE_TYPE', 'CEPH')
@pytest.mark.usefixtures(log_global_env_facts)
def start_and_prepare_env():
pass
class TestMe(object):
def test_foo(self):
assert True
This will add a property node below the testsuite node to the generated
xml:
<testsuite errors="0" failures="0" name="pytest" skips="0" tests="1" time="0.006">
<properties>
<property name="ARCH" value="PPC"/>
<property name="STORAGE_TYPE" value="CEPH"/>
</properties>
<testcase classname="test_me.TestMe" file="test_me.py" line="16" name="test_foo" time="0.000243663787842"/>
</testsuite>
WARNING:
This is an experimental feature, and its interface might be replaced
by something more powerful and general in future versions. The func‐
tionality per-se will be kept.
CREATING RESULTLOG FORMAT FILES
Deprecated since version 3.0: This option is rarely used and is sched‐
uled for removal in 4.0.
To create plain-text machine-readable result files you can issue:
pytest --resultlog=path
and look at the content at the path location. Such files are used e.g.
by the PyPy-test web page to show test results over several revisions.
SENDING TEST REPORT TO ONLINE PASTEBIN SERVICE
Creating a URL for each test failure:
pytest --pastebin=failed
This will submit test run information to a remote Paste service and
provide a URL for each failure. You may select tests as usual or add
for example -x if you only want to send one particular failure.
Creating a URL for a whole test session log:
pytest --pastebin=all
Currently only pasting to the http://bpaste.net service is implemented.
DISABLING PLUGINS
To disable loading specific plugins at invocation time, use the -p
option together with the prefix no:.
Example: to disable loading the plugin doctest, which is responsible
for executing doctest tests from text files, invoke pytest like this:
pytest -p no:doctest
CALLING PYTEST FROM PYTHON CODE
New in version 2.0.
You can invoke pytest from Python code directly:
pytest.main()
this acts as if you would call "pytest" from the command line. It will
not raise SystemExit but return the exitcode instead. You can pass in
options and arguments:
pytest.main(['-x', 'mytestdir'])
You can specify additional plugins to pytest.main:
# content of myinvoke.py
import pytest
class MyPlugin(object):
def pytest_sessionfinish(self):
print("*** test run reporting finishing")
pytest.main(["-qq"], plugins=[MyPlugin()])
Running it will show that MyPlugin was added and its hook was invoked:
$ python myinvoke.py
*** test run reporting finishing
AUTHOR
holger krekel at merlinux eu
COPYRIGHT
2017, holger krekel and pytest-dev team
3.2.1 Sep 04, 2017 PYTEST(1)
