Skip to main content

Parameterized testing with any Python test framework

Project description

Parameterized testing in Python sucks.

nose-parameterized fixes that. For everything. Parameterized testing for nose, parameterized testing for py.test, parameterized testing for unittest.

# test_math.py
from nose.tools import assert_equal
from nose_parameterized import parameterized

import unittest
import math

@parameterized([
    (2, 2, 4),
    (2, 3, 8),
    (1, 9, 1),
    (0, 9, 0),
])
def test_pow(base, exponent, expected):
    assert_equal(math.pow(base, exponent), expected)

class TestMathUnitTest(unittest.TestCase):
    @parameterized.expand([
        ("negative", -1.5, -2.0),
        ("integer", 1, 1.0),
        ("large fraction", 1.6, 1),
    ])
    def test_floor(self, name, input, expected):
        assert_equal(math.floor(input), expected)

With nose (and nose2):

$ nosetests -v test_math.py
test_math.test_pow(2, 2, 4) ... ok
test_math.test_pow(2, 3, 8) ... ok
test_math.test_pow(1, 9, 1) ... ok
test_math.test_pow(0, 9, 0) ... ok
test_floor_0_negative (test_math.TestMathUnitTest) ... ok
test_floor_1_integer (test_math.TestMathUnitTest) ... ok
test_floor_2_large_fraction (test_math.TestMathUnitTest) ... ok

----------------------------------------------------------------------
Ran 7 tests in 0.002s

OK

As the package name suggests, nose is best supported and will be used for all further examples.

With py.test (version 2.0 and above):

$ py.test -v test_math.py
============================== test session starts ==============================
platform darwin -- Python 2.7.2 -- py-1.4.30 -- pytest-2.7.1
collected 7 items

test_math.py::test_pow::[0] PASSED
test_math.py::test_pow::[1] PASSED
test_math.py::test_pow::[2] PASSED
test_math.py::test_pow::[3] PASSED
test_math.py::TestMathUnitTest::test_floor_0_negative
test_math.py::TestMathUnitTest::test_floor_1_integer
test_math.py::TestMathUnitTest::test_floor_2_large_fraction

=========================== 7 passed in 0.10 seconds ============================

With unittest (and unittest2):

$ python -m unittest -v test_math
test_floor_0_negative (test_math.TestMathUnitTest) ... ok
test_floor_1_integer (test_math.TestMathUnitTest) ... ok
test_floor_2_large_fraction (test_math.TestMathUnitTest) ... ok

----------------------------------------------------------------------
Ran 3 tests in 0.000s

OK

(note: because unittest does not support test decorators, only tests created with @parameterized.expand will be executed)

Compatibility

Yes.

Py2.6

Py2.7

Py3.3

Py3.4

PyPy

nose

yes

yes

yes

yes

yes

nose2

yes

yes

yes

yes

yes

py.test

yes

yes

yes

yes

yes

unittest
(@parameterized.expand)

yes

yes

yes

yes

yes

unittest2
(@parameterized.expand)

yes

yes

yes

yes

yes

Dependencies

(this section left intentionally blank)

Exhaustive Usage Examples

The @parameterized and @parameterized.expand decorators accept a list or iterable of tuples or param(...), or a callable which returns a list or iterable:

from nose_parameterized import parameterized, param

# A list of tuples
@parameterized([
    (2, 3, 5),
    (3, 5, 8),
])
def test_add(a, b, expected):
    assert_equal(a + b, expected)

# A list of params
@parameterized([
    param("10", 10),
    param("10", 16, base=16),
])
def test_int(str_val, expected, base=10):
    assert_equal(int(str_val, base=base), expected)

# An iterable of params
@parameterized(
    param.explicit(*json.loads(line))
    for line in open("testcases.jsons")
)
def test_from_json_file(...):
    ...

# A callable which returns a list of tuples
def load_test_cases():
    return [
        ("test1", ),
        ("test2", ),
    ]
@parameterized(load_test_cases)
def test_from_function(name):
    ...

Note that, when using an iterator or a generator, Nose will read every item into memory before running any tests (as it first finds and loads every test in each test file, then executes all of them at once).

The @parameterized decorator can be used test class methods, and standalone functions:

from nose_parameterized import parameterized

class AddTest(object):
    @parameterized([
        (2, 3, 5),
    ])
    def test_add(self, a, b, expected):
        assert_equal(a + b, expected)

@parameterized([
    (2, 3, 5),
])
def test_add(a, b, expected):
    assert_equal(a + b, expected)

And @parameterized.expand can be used to generate test methods in situations where test generators cannot be used (for example, when the test class is a subclass of unittest.TestCase):

import unittest
from nose_parameterized import parameterized

class AddTestCase(unittest.TestCase):
    @parameterized.expand([
        ("2 and 3", 2, 3, 5),
        ("3 and 5", 2, 3, 5),
    ])
    def test_add(self, _, a, b, expected):
        assert_equal(a + b, expected)

Will create the test cases:

$ nosetests example.py
test_add_0_2_and_3 (example.AddTestCase) ... ok
test_add_1_3_and_5 (example.AddTestCase) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.001s

OK

Note that @parameterized.expand works by creating new methods on the test class. If the first parameter is a string, that string will be added to the end of the method name. For example, the test case above will generate the methods test_add_0_2_and_3 and test_add_1_3_and_5.

The names of the test cases generated by @parameterized.expand can be customized using the testcase_func_name keyword argument. The value should be a function which accepts three arguments: testcase_func, param_num, and params, and it should return the name of the test case. testcase_func will be the function to be tested, param_num will be the index of the test case parameters in the list of parameters, and param (an instance of param) will be the parameters which will be used.

import unittest
from nose_parameterized import parameterized

def custom_name_func(testcase_func, param_num, param):
    return "%s_%s" %(
        testcase_func.__name__,
        parameterized.to_safe_name("_".join(str(x) for x in param.args)),
    )

class AddTestCase(unittest.TestCase):
    @parameterized.expand([
        (2, 3, 5),
        (2, 3, 5),
    ], testcase_func_name=custom_name_func)
    def test_add(self, a, b, expected):
        assert_equal(a + b, expected)

Will create the test cases:

$ nosetests example.py
test_add_1_2_3 (example.AddTestCase) ... ok
test_add_2_3_5 (example.AddTestCase) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.001s

OK

The param(...) helper class stores the parameters for one specific test case. It can be used to pass keyword arguments to test cases:

from nose_parameterized import parameterized, param

@parameterized([
    param("10", 10),
    param("10", 16, base=16),
])
def test_int(str_val, expected, base=10):
    assert_equal(int(str_val, base=base), expected)

FAQ

If all the major testing frameworks are supported, why is it called nose-parameterized?

Originally only nose was supported. But now everything is supported!

What do you mean when you say “nose is best supported”?

There are small caveates with py.test and unittest: py.test does not show the parameter values (ex, it will show test_add[0] instead of test_add[1, 2, 3]), and unittest/unittest2 do not support test generators so @parameterized.expand must be used.

Why not use @pytest.mark.parametrize?

Because spelling is difficult. Also, nose-parameterized doesn’t require you to repeat argument names, and (using param) it supports optional keyword arguments.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

nose-parameterized-0.5.0.tar.gz (10.4 kB view hashes)

Uploaded source

Built Distribution

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor NVIDIA NVIDIA PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page