Parameterized testing with any Python test framework
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.
ย | 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)
If test cases have a docstring, the parameters for that test case will be
appended to the first line of the docstring. This behavior can be controlled
with the doc_func
argument:
from nose_parameterized import parameterized
@parameterized([
(1, 2, 3),
(4, 5, 9),
])
def test_add(a, b, expected):
""" Test addition. """
assert_equal(a + b, expected)
def my_doc_func(func, num, param):
return "%s: %s with %s" %(num, func.__name__, param)
@parameterized([
(5, 4, 1),
(9, 6, 3),
], doc_func=my_doc_func)
def test_subtraction(a, b, expected):
assert_equal(a - b, expected)
$ nosetests example.py Test addition. [with a=1, b=2, expected=3] ... ok Test addition. [with a=4, b=5, expected=9] ... ok 0: test_subtraction with param(*(5, 4, 1)) ... ok 1: test_subtraction with param(*(9, 6, 3)) ... ok ---------------------------------------------------------------------- Ran 4 tests in 0.001s OK
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
andunittest
:py.test
does not show the parameter values (ex, it will showtest_add[0]
instead oftest_add[1, 2, 3]
), andunittest
/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 (usingparam
) it supports optional keyword arguments.