- Python 2.7 or 3.7 and later
- Provide pytest.mark.randomize function for generating random test data
$ pip install pytest-quickcheck
Just pass the signature of function to randomize marker. The signature is represented a tuple consist of argument name and its type.
@pytest.mark.randomize(i1=int, i2=int, ncalls=1) def test_generate_ints(i1, i2): pass
More complex data structure:
@pytest.mark.randomize( d1={'x': int, 'y': [str, (int, int)], 'z': {'x': str}} ) def test_generate_dict(d1): pass
The randomize marker is able to use with parametrize marker.
@pytest.mark.parametrize("prime", [2, 3, 5]) @pytest.mark.randomize(i1=int, f1=float, ncalls=1) def test_gen_parametrize_with_randomize_int_float(prime, i1, f1): pass
Using command line option --randomize
restricts only the randomize test.
$ py.test -v --randomize test_option.py ========================================================================================== test session starts ========================================================================================== test_option.py:5: test_normal SKIPPED test_option.py:8: test_generate_ints[74-22] PASSED
There some options for each data type:
$ py.test --markers @pytest.mark.randomize(argname=type, **options): mark the test function with random data generating any data type. There are options for each data type: (see doc for details) int: ['min_num', 'max_num'] float: ['min_num', 'max_num', 'positive'] str: ['encoding', 'fixed_length', 'min_length', 'max_length', 'str_attrs'] list_of, nonempty_list_of, dict_of: ['items', 'min_items', 'max_items']
common option
ncalls: set the number of calls. Defaults to 3. (e.g. ncalls=5)choices: choose from given sequence. (e.g. choices=[3, 5, 7])int
min_num: lower limit for generating integer number. (e.g. min_num=0)max_num: upper limit for generating integer number. (e.g. max_num=10)float
min_num: lower limit for generating real number. (e.g. min_num=0.0)max_num: upper limit for generating real number. (e.g. max_num=1.0)positive: generate only positive real number if set to True. Defaults to False. (e.g. positive=True)str
encoding: generate unicode string encoded given character code. (e.g. encoding="utf-8") # for Python 2.x onlyfixed_length: generate fixed length string. (e.g. fixed_length=8)max_length: generate the string less than or equal to max length (e.g. max_length=32)str_attrs: generate the string in given letters. set a tuple consist of attribute names in the string module. (e.g. str_attrs=("digits", "punctuation")list_of, nonempty_list_of, dict_of
items: number of items.min_items: lower limit on number of items.max_items: upper limit on number of items.
Probably, tests/test_plugin_basic.py is useful for learning how to use these options.
To generate a variable length list of items:
from pytest import list_of @pytest.mark.randomize(l=list_of(int)) def test_list_of(l): pass
You can control its size with the items
, min_items
and
max_items
options, or use the nonempty_list_of
shortcut.
@pytest.mark.randomize(l=list_of(int, num_items=10)) def test_list_of_length(l): assert len(l) == 10 @pytest.mark.randomize(l=list_of(int, min_items=10, max_items=100)) def test_list_of_minimum_length(l): assert len(l) >= 10 from pytest import nonempty_list_of @pytest.mark.randomize(l=nonempty_list_of(int) def test_list_of_minimum_length(l): assert len(l) >= 1
Options for data types work as usual:
@pytest.mark.randomize(l=list_of(str, num_items=10), choices=["a", "b", "c"]) def test_list_of(l): assert l[0] in ["a", "b", "c"]
(Note what goes into the list_of()
call and what goes outside.)
You can also generate a dict:
from pytest import dict_of @pytest.mark.randomize(d=dict_of(str, int)) def test_list_of(l): pass
For Python 3, the signature of function is given as function annotation.
@pytest.mark.randomize(min_num=0, max_num=2, ncalls=5) def test_generate_int_anns(i1: int): pass
Mixed representation is also OK, but it might not be useful.
@pytest.mark.randomize(i1=int, fixed_length=8) def test_generate_arg_anns_mixed(i1, s1: str): pass
See also: PEP 3107 -- Function Annotations
Under 0.6 version, types were specified by strings containing the name of the type. It's still supported if you like.
@pytest.mark.randomize(("i1", "int"), ("i2", "int"), ncalls=1)