pytest.org

pytest

Table of Contents

• Usage
• Test Layouts
• raises and fail

Usage

• http://doc.pytest.org/en/latest/usage.html

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
pytest -x          # stop after first failure
pytest --maxfail=2 # stop after two failures
pytest test_mod.py # run tests in module
pytest somepath    # run all tests below somepath

# only run tests with names that match the # "string expression".
# e.g. "MyClass and not method" # will select
# TestMyClass.test_something but not TestMyClass.test_method_simple
pytest -k stringexpr

# only run tests that match the "node ID",
pytest test_mod.py::test_func
pytest test_mod.py::TestClass::test_method

pytest --pyargs pkg # run all tests found below directory of pkg

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

pytest --pdb           # drop into the PDB prompt
pytest --durations=10  # To get a list of the slowest 10 test durations

Test Layouts

• http://doc.pytest.org/en/latest/goodpractices.html

---

Useful if you have many functional tests or for other reasons want to keep tests separate from actual application code (often a good idea):

setup.py   # your setuptools Python package metadata
mypkg/
    __init__.py
    appmodule.py
tests/
    test_app.py
    ...

---

Useful if you have direct relation between (unit-)test and application modules and want to distribute your tests along with your application:

setup.py   # your setuptools Python package metadata
mypkg/
    __init__.py
    appmodule.py
    ...
    test/
        test_app.py
        ...

---

pytest tests/test_app.py       # for external test dirs
pytest mypkg/test/test_app.py  # for inlined test dirs
pytest mypkg                   # run tests in all below test directories
pytest                         # run all tests below current dir

raises and fail

• http://doc.pytest.org/en/latest/assert.html#assertions-about-expected-exceptions
• http://stackoverflow.com/questions/20274987/how-to-use-pytest-to-check-that-error-is-not-raised

import pytest

def test_zero_division():
    with pytest.raises(ZeroDivisionError):
        1 / 0

def test_foo3():
    try:
        foo(7)
    except MyError:
        pytest.fail("Unexpected MyError ..")