Function create_autospec

Lib/unittest/mock.py:2748–2909

Create a mock object using another object as a spec. Attributes on the mock will use the corresponding attribute on the `spec` object as their spec. Functions or methods being mocked will have their arguments checked to check that they are called with the correct signature. If

(spec, spec_set=False, instance=False, _parent=None,
                    _name=None, *, unsafe=False, **kwargs)

def create_autospec(spec, spec_set=False, instance=False, _parent=None,
                    _name=None, *, unsafe=False, **kwargs):
    """Create a mock object using another object as a spec. Attributes on the
    mock will use the corresponding attribute on the `spec` object as their
    spec.

    Functions or methods being mocked will have their arguments checked
    to check that they are called with the correct signature.

    If `spec_set` is True then attempting to set attributes that don't exist
    on the spec object will raise an `AttributeError`.

    If a class is used as a spec then the return value of the mock (the
    instance of the class) will have the same spec. You can use a class as the
    spec for an instance object by passing `instance=True`. The returned mock
    will only be callable if instances of the mock are callable.

    `create_autospec` will raise a `RuntimeError` if passed some common
    misspellings of the arguments autospec and spec_set. Pass the argument
    `unsafe` with the value True to disable that check.

    `create_autospec` also takes arbitrary keyword arguments that are passed to
    the constructor of the created mock."""
    if _is_list(spec):
        # can't pass a list instance to the mock constructor as it will be
        # interpreted as a list of strings
        spec = type(spec)

    is_type = isinstance(spec, type)
    if _is_instance_mock(spec):
        raise InvalidSpecError(f'Cannot autospec a Mock object. '
                               f'[object={spec!r}]')
    is_async_func = _is_async_func(spec)
    _kwargs = {'spec': spec}

    entries = [(entry, _missing) for entry in dir(spec)]
    if is_type and instance and is_dataclass(spec):
        is_dataclass_spec = True
        dataclass_fields = fields(spec)
        entries.extend((f.name, f.type) for f in dataclass_fields)
        dataclass_spec_list = [f.name for f in dataclass_fields]
    else:
        is_dataclass_spec = False

    if spec_set:
        _kwargs = {'spec_set': spec}
    elif spec is None:
        # None we mock with a normal mock without a spec
        _kwargs = {}
    if _kwargs and instance:
        _kwargs['_spec_as_instance'] = True
    if not unsafe:
        _check_spec_arg_typos(kwargs)

    _name = kwargs.pop('name', _name)
    _new_name = _name
    if _parent is None:
        # for a top level object no _new_name should be set