WMUL-FM Test Untilities

These are utilities that help with testing WMUL-FM's other python modules.

1. make_namedtuple creates one-off named tuples for concisely passing data from the fixture method to the test methods.

2. generate_true_false_matrix_from_named_tuple creates a list of true and false values, and a list of corresponding ids, to be passed into a pytest test fixture.

3. generate_true_false_matrix_from_list_of_strings is a convenience function. If you give it a string name, and a list of strings, it will create a named tuple from those and then call generate_true_false_matrix_from_named_tuple.

4. generate_combination_matrix_from_dataclass When given a dataclass (the class, not an instance), whose fields are all either boolean or enums, it will return two lists. The first list will contain instances of the dataclass covering all possible values of the fields. The second list will be the test_ids of those instances. These are indended to be passed to a pytest fixture.

5. assert_has_only_these_calls receives a unittest.mock object and asserts that it has been called with the specified calls and only the specified calls. The counts are compared and then the mock_calls list is checked for the calls.

6. assert_lists_contain_same_items asserts that every item in list one is also in list2 and vice-versa, in any order.

make_namedtuple(class_name, **fields)

class_name: The name of the tuple class. Same as namedtuple(class_name=).

fields: A keyword dictionary of field names and values. The names are the same as namedtuple(field_names=).

returns A namedtuple of type class_name, with field_names corresponding to the keys of the fields dictionary and field values corresponding to the values of the fields dictionary.

enterprise = make_namedtuple("Starship", name="U.S.S. Enterprise", registry_number="NCC-1701")

is the same as

starship_tuple = namedtuple("Starship", ["name", "registry_number"])
enterprise = starship_tuple("U.S.S. Enterprise", "NCC-1701")

This is useful when you want to make a one-off namedtuple. It can be used to pass data concisely from a testing fixture to the test methods.

generate_true_false_matrix_from_namedtuple(input_namedtuple)

input_namedtuple A named tuple whose fields will be used to generate the True False matrix.

returns Two lists: true_false_matrix and test_ids. The True-False matrix is a list of the namedtuples that is of size len(input_tuple) and with the fields set to every combination of True and False. The list of ids is a list of strings that describe the corresponding tuples.

Given: input_tuple = namedtuple("burger_toppings", ["with_cheese", "with_ketchup", "with_mustard"])

true_false_matrix will be:

[
    burger_toppings(with_cheese=False, with_ketchup=False, with_mustard=False),
    burger_toppings(with_cheese=True,  with_ketchup=False, with_mustard=False),
    burger_toppings(with_cheese=False, with_ketchup=True,  with_mustard=False),
    burger_toppings(with_cheese=True,  with_ketchup=True,  with_mustard=False),
    burger_toppings(with_cheese=False, with_ketchup=False, with_mustard=True),
    burger_toppings(with_cheese=True,  with_ketchup=False, with_mustard=True),
    burger_toppings(with_cheese=False, with_ketchup=True,  with_mustard=True),
    burger_toppings(with_cheese=True,  with_ketchup=True,  with_mustard=True)
]

and test_ids will be:

[
    'burger_toppings(with_cheese=False, with_ketchup=False, with_mustard=False)',
    'burger_toppings(with_cheese=True,  with_ketchup=False, with_mustard=False)',
    'burger_toppings(with_cheese=False, with_ketchup=True,  with_mustard=False)',
    'burger_toppings(with_cheese=True,  with_ketchup=True,  with_mustard=False)',
    'burger_toppings(with_cheese=False, with_ketchup=False, with_mustard=True)',
    'burger_toppings(with_cheese=True,  with_ketchup=False, with_mustard=True)',
    'burger_toppings(with_cheese=False, with_ketchup=True,  with_mustard=True)',
    'burger_toppings(with_cheese=True,  with_ketchup=True,  with_mustard=True)'
]

Note that true_false_matrix is a list of namedtuples and test_ids is a list of the string representations of those same namedtuples.

generate_true_false_matrix_from_list_of_strings(name, input_strings):

A convenience function. It takes a string name and a list of strings, and returns the true-false matrix built from those values.

generate_true_false_matrix_from_list_of_strings(
    "burger_toppings",
    ["with_cheese", "with_ketchup", "with_mustard"]
)

is the equivalent of

burger_toppings = namedtuple(
    "burger_toppings", 
    ["with_cheese", "with_ketchup", "with_mustard"]
)
generate_true_false_matrix_from_namedtuple(burger_toppings)

generate_combination_matrix_from_dataclass(input_dataclass: dataclasses.dataclass) -> list:

When given a dataclass (the class, not an instance), whose fields are all either boolean or enums, it will return two lists. The first list will contain instances of the dataclass covering all possible values of the fields. The second list will be the test_ids of those instances. If the dataclass provides a .test_id(self) function, that function will be used to generate the test_ids. Otherwise, the dataclass's __str__(self) function will be used.

Function will generate up to a maximum of 1,000,000 instances. That limit was chosen arbitrarily and may be changed with testing.

input_dataclass A dataclass (not an instance), whose fields are all either boolean or enums.
returns Two lists: dataclass_matrix and test_ids. dataclass_matrix is the list of instances of input_dataclass covering all possible values of the fields. test_ids is the list of strings that describe those instances.
raises TypeError If input_dataclass is not a dataclass or is an instance of a dataclass.
raises TypeError If any of the fields of the dataclass are not a subclass of either bool or Enum.
raises ValueError If the total number of possible values excees 1,000,000.

Given:

class Colors(Enum):
    BROWN = 0
    BLACK = 1
    RED = 2

@dataclass
class Car:
    runs: bool
    color: Colors
        
    def test_id(self):
        return f"Car(runs={self.runs}, color={self.color})"

dataclass_matrix will be:

[
    Car(runs=True, color=Colors.BLACK),
    Car(runs=True, color=Colors.BROWN),
    Car(runs=True, color=Colors.RED),
    Car(runs=False, color=Colors.BLACK),
    Car(runs=False, color=Colors.BROWN),
    Car(runs=False, color=Colors.RED)
]

test_ids will be:

[
    "Car(runs=True, color=Colors.BLACK)",
    "Car(runs=True, color=Colors.BROWN)",
    "Car(runs=True, color=Colors.RED)",
    "Car(runs=False, color=Colors.BLACK)",
    "Car(runs=False, color=Colors.BROWN)",
    "Car(runs=False, color=Colors.RED)"
]

assert_has_only_these_calls(mock, calls, any_order=False)

mock a unittest.mock object.

calls a list of calls.

If any_order is False (the default) then the calls must be sequential.

If any_order is True then the calls can be in any order, but they must all appear in mock_calls.

assert the mock has been called with the specified calls and only the specified calls. The counts are compared and then assert_has_calls is called.

This is the natural continuation of assert_called_once_with and is based on that method.

assert_lists_contain_same_items(list1, list2)

Asserts that every item in list one is also in list2 and vice-versa, in any order. If they have to be in the same order, use list1 == list2.

list1 The first list to compare.
list2 The second list to compare.
raises AssertionError If any item in one list is not also in the other list.

FieldToReplace

This class is used by the replace_with_fake_data method. A list of these objects is passed to replace_with_fake_data to describe which fields on the input_object need to be replaced and how.

field_name (str): The name of the field on the object that is to be replaced.

replacement_function (callable): The return value of this function will be set as the new value of the field. The function must take either no arguments (if pass_existing_value is False), or one positional argument (if pass_existing_value is True and existing_value_kwarg is falsy), or one key-work argument (if pass_existing_value is True and existing_value_kwarg is a string).

pass_existing_value (bool): If this is set to true, then the existing value of the field will be passed to the replacement_function. Defaults to False.

existing_value_kwarg (str): If this is set to a truthy value and pass_existing_value is True, then the existing value will be passed to replacement_function with this string as the keyword. If pass_existing_value is False, then this value will be ignored. Defaults to empty string, a falsy value.

Examples:
See replace_with_fake_data

replace_with_fake_data(input_object: object, fields_to_replace: List[FieldToReplace], error_if_non_existant = True) -> object

Makes a shallow copy of input_object, then replaces fields of input_object with fake data generated by a passed-in function.

Args:
input_object (object): The object whose fields are to be replaced.

fields_to_replace (List[FieldToReplace]): A list of FieldToReplaces. All of the fields on input_object will be replaced using the function provided in FieldToReplace.

error_if_non_existant (bool, optional): If True, raise AttributeError (from getattr) if a provided field does not already exist. If False, any non-existant fields will be added and set to the value provided by the function. Defaults to True.

Returns:
object: A shallow copy of input_object, with the fields replaced by the values of the provided functions.

Examples:
Using faker https://github.com/joke2k/faker to generate new text.

from faker import Faker
fake = Faker()

@dataclass
class DummyObject:
    name: str
    address: str
    age: int
    tricorder: object

obj1 = DummyObject(
    name="Kyle Alexander",
    address="3986 Guerra Ports Suite 164\nWest Kimfurt, KY 22894",
    age=4,
    tricorder=object()
)

fields_to_replace1 = [
    FieldToReplace(
        field_name="name"
        replacement_function=fake.text
    )
]

modified_object1 = replace_with_fake_data(obj1, fields_to_replace1)

modified_object1 will be a shallow copy of obj1 with the .name field replaced by the value of the fake.text function.

fields_to_replace2 = [
    FieldToReplace(field_name="name", replacement_function=fake.name),
    FieldToReplace(field_name="age", replacement_function=lambda: fake.random_int(1, 99)),
    FieldToReplace(field_name="tricorder", replacement_function=object),
]
modified_object2 = replace_with_fake_data(obj1, fields_to_replace2)

modified_object2 will be a shallow copy of obj1 with the .name field replaced by the value of the fake.name function, .age replaced by a random int between 1 and 99, and .tricorder replaced by a new object.

fields_to_replace3 = [FieldToReplace(field_name="foo", replacement_function=fake.name)]
modified_object3 = replace_with_fake_data(
    input_object=obj1, 
    fields_to_replace=fields_to_replace3, 
    error_if_non_existant=False
)

modified_object3 will be a shallow copy of obj1 with the .foo field added and set to the value of the fake.name function.

fields_to_replace4 = [FieldToReplace(field_name="foo", replacement_function=faker.name)]
modified_object4 = replace_with_fake_data(
    input_object=obj1, 
    fields_to_replace=fields_to_replace4, 
    error_if_non_existant=True
)

In this case, an AttributeError will be raised because obj1.foo does not exist.

def backwards1(input_str):
    return "".join(reversed(input_str))

fields_to_replace5 = [
    FieldToReplace(field_name="name", replacement_function=backwards1, pass_existing_value=True)
]

modified_object5 = replace_with_fake_data(
    input_object=obj1,
    fields_to_replace=fields_to_replace5
)

modified_object5 will be a shallow copy of obj1 with the .name field set to rednaxelA elyK.

def backwards2(*, input_str, titlecase=True):
    reversed_string = "".join(reversed(input_str))
    if titlecase:
        return reversed_string.title()
    else:
        return reversed_string

fields_to_replace6 = [
    FieldToReplace(field_name="name", replacement_function=backwards2, pass_existing_value=True)
]

modified_object6 = replace_with_fake_data(
    input_object=obj1,
    fields_to_replace=fields_to_replace6
)

modified_object6 will be a shallow copy of obj1 with the .name field set to Rednaxela Elyk.