Mocked Call Verification

Verify Last Call

The general form is:

assert that(<mock>).last_call == (<args-tuple>)

Or if it was called with keyword arguments:

assert that(<mock>).last_call == ((<args-tuple>), {<keyword-args>})

>>> class GrailSeeker:
...     def travel_to(self, place: str, when: str = "Someday"):
...         pass

>>> arthur = mock(GrailSeeker)

>>> arthur.travel_to("Camelot")

>>> assert that(arthur.travel_to).last_call == ("Camelot",)

>>> arthur.travel_to("Camelot", when="Now")

>>> assert that(arthur.travel_to).last_call == (("Camelot",), {"when": "Now"})

Verify Nth Call

The general form is similar to checking for the last call:

assert that(<mock>).nth_call(<N>) == (<args-tuple>)

Where <N> is a number from zero up to the number of calls made, exclusive.

Verify Number of Calls

The general form is similar to checking for the last call:

assert that(<mock>).num_calls ...

For example:

>>> assert that(arthur.travel_to).num_calls >= 1

Verify Mock Was/Not Called

The general form is similar to checking for the last call:

assert that(<mock>).<was_called|was_not_called>

For example:

>>> assert that(arthur.travel_to).was_called

>>> assert that(arthur.travel_to).was_not_called
Traceback (most recent call last):
...
AssertionError

Capture Call Details

Sometimes it’s useful to make more targetted or repeated assertions about a subset of what a mocked method was called with.

To make this easier you can retrieve call details and assign them to a variable.

To capture the details of calls that were made you can use expressions such as:

<var> = spy(<mock>).last_call
<var> = spy(<mock>).nth_call(<N>)
etc.

Note

The spy() function is just a synonym for that().

Example:

>>> class SpanishInquisition:
...     def surprise(self, location: str, interrogator: str) -> str:
...         raise NotImplementedError()

>>> inquisitors = mock(SpanishInquisition)

>>> when(inquisitors.surprise).any_call().then(
...     lambda location, interrogator: (
...         f"The Spanish Inquisition surprises {location} with {interrogator}!"
...     )
... )

>>> inquisitors.surprise("the village", interrogator="Cardinal Biggles")
'The Spanish Inquisition surprises the village with Cardinal Biggles!'

>>> args, kwargs = spy(inquisitors.surprise).last_call

>>> args
('the village',)
>>> assert args[0] == "the village"

>>> kwargs
{'interrogator': 'Cardinal Biggles'}
>>> assert kwargs.get("interrogator") == "Cardinal Biggles"

Capture Details for All Calls

If you prefer to capture the details of all calls that were made for deeper inspection you can use the all_calls attribute of the spy object using expressions such as:

<var> = spy(<mock>).all_calls

Example:

>>> class SpanishInquisition:
...     def surprise(self, location: str, interrogator: str) -> str:
...         raise NotImplementedError()

>>> inquisitors = mock(SpanishInquisition)

>>> when(inquisitors.surprise).any_call().then(
...     lambda location, interrogator: (
...         f"The Spanish Inquisition surprises {location} with {interrogator}!"
...     )
... )

>>> inquisitors.surprise("the village", interrogator="Cardinal Biggles")
'The Spanish Inquisition surprises the village with Cardinal Biggles!'

>>> inquisitors.surprise("the castle", interrogator="Cardinal Fang")
'The Spanish Inquisition surprises the castle with Cardinal Fang!'

>>> inquisitors.surprise("the town square", interrogator="Cardinal Ximinez")
'The Spanish Inquisition surprises the town square with Cardinal Ximinez!'

>>> all_calls = spy(inquisitors.surprise).all_calls

>>> locations = [call.args[0] for call in all_calls]
>>> interrogators = [call.kwargs.get("interrogator") for call in all_calls]

>>> assert locations == ["the village", "the castle", "the town square"]
>>> assert interrogators == ["Cardinal Biggles", "Cardinal Fang", "Cardinal Ximinez"]