A Python function "what" after Ruby gem "what_methods". "what" function checks all the method of an object and returns the method names which match the expected result. Ruby gem what_methods is here: https://github.com/BMorearty/what_methods

what_methods_python.py

# coding: utf-8

"""
A Python function "what" after Ruby gem "what_methods".
"what" function checks all the method of an object
and returns the method names which match the expected result.

Last updated: 2013/12/23
"""

from copy import copy
import unittest


def what(obj, expected, *args):
    """returns method names which match the expected result.

    @param obj  An object you want to check the methods of.
    @param result  The expected result of the method execution.
    @param args  Parameters to pass to the methods.
    @return A list of method names whose returned value matches the expectation.
    """

    # Get all the callable attributes.
    # [(name, body), ...]
    methods = [x for x in dir(obj) \
                       if callable(getattr(obj, x))]

    # Get the attributes whose returned value matches the expected one.
    methods_matched = []
    for method in methods:
        obj_copied = copy(obj)
        try:
            actual = getattr(obj_copied, method)(*args)
            if actual == expected:
                methods_matched.append(method)
        except (AttributeError, LookupError, TypeError, ValueError) as e:
            pass

    return methods_matched


class TestWhat(unittest.TestCase):
    """TestCases for what function
    """
    def test_int(self):
        self.assertIn("__add__", what(3, 5, 2))
        self.assertIn("__sub__", what(3, 2, 1))

    def test_float(self):
        self.assertIn("__int__", what(3.14, 3))

    def test_string(self):
        s1 = "abc"
        self.assertIn("__len__", what(s1, 3))
        self.assertIn("__getitem__", what(s1, "c", -1))
        self.assertIn("__add__", what(s1, "abcd", "d"))

    def test_list(self):
        self.assertIn("__getitem__", what(["cat", "dog", "elephant"], "elephant", -1))
        self.assertIn("pop", what(["cat", "dog"], "dog"))

    def test_dict(self):
        self.assertIn("__len__", what({"ab": 3, "bb": 5}, 2))
        self.assertIn("__getitem__", what({"ab": 3, "bb": 5}, 3, "ab"))


if __name__ == "__main__":
    unittest.main()