Pytest | Note of Thi

The last modifications of this post were around 4 years ago, some information may be outdated!

This is a draft, the content is not complete and of poor quality!

On this page

Install
Rules
Executing
Simple
With parameters
Custom marker
Errors
Ignore warning
References

Install

pip install pytest

Rules

Name all testing files with^[ref] test_*.py or *_test.py.
Name all "be tested" functions with def test_*.

Executing

-rf: list files having bugs.
Most useful command lines.

pytest test_sample.py
pytest -q test_sample.py # quiet mode

# ignore all files in folder statistics
pytest -k "not statistics"

Simple

# test_sample.py
def func(x):
    return x + 1

def test_answer():
    assert func(3) == 5

# then run
pytest test_sample.py

With parameters

# test_sample.py
@pytest.mark.parametrize(
    "input, param_1, param_2, result",
    [
        (df_1, 'date', np.mean, df_result_1),
        (df_2, 'date', np.mean, df_result_2),
    ]
)

def test_run(input, param_1, param_2, result):
    spts = SPTS(param_1=param_1, param_2=param_2)
    df_tmp = spts.run(df)
    assert isinstance(df_tmp, pd.DataFrame)
    assert df_tmp.equals(result)

# To get all combinations
@pytest.mark.parametrize("x", [0, 1])
@pytest.mark.parametrize("y", [2, 3])

def test_foo(x, y):
    pass

# Then the arguments set to `x=0/y=2`,
#    `x=1/y=2`, `x=0/y=3`, and `x=1/y=3`.

Note that, @pytest.mark.parametrize must be placed right before the function who uses it. Otherwise, there is an error fixture not found.

# ERROR
@pytest.mark.parametrize("x", [0, 1])
def test_foo(x):
    pass

def test_bar(x):
    pass

# FIX
@pytest.mark.parametrize("x", [0, 1])
def test_foo(x):
    pass

@pytest.fixture
def test_bar(x):
    pass

Custom marker

Run tests who have a specific marker.^[ref]

@pytest.mark.marker_1
def test_func1():
    pass

@pytest.mark.marker_2
def test_func2():
    pass

@pytest.mark.marker_1
def test_func3():
    pass

# with tag 'marker_1'
pytest -v -m marker_1

# except tag 'marker_1'
pytest -v -m 'not marker_1'

Errors

# ImportError: No module named atomicwrites
python -m pytest
python3 -m pytest

Ignore warning

👉 Main reference.

# eg: RuntimeWarning: numpy.ufunc size changed,
@pytest.mark.filterwarnings('ignore::RuntimeWarning')
@pytest.mark.level_1
def test_load(df_test, report):

References

pytest official docs.

Pytest ^draft