[TIP] Error with Checking Calls to Multiple Mocks

[John Papanastasiou]

Apologies, the code I posted was missing an important print statement.
 I've attached the corrected script and more useful sample output:

Regards,

John.

 ./nested_calls.py
..
Mock: top_level: <mock.MagicMock object at 0x1005675d0>
Mock: nested: <mock.Mock object at 0x10059a990>
Call Args, top_level.handler.trigger: [(({'event': <mock.Mock object at
0x10059a990>},), {})]
Mock: nested: <mock.Mock object at 0x10059a990>
Call Args, nested.handler.trigger: [(({'event': <mock.Mock object at
0x10059a990>},), {})]

F
======================================================================
FAIL: test_top_level_and_extra (__main__.TestNestedCalls)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "./nested_calls.py", line 54, in test_top_level_and_extra
    top_level.handler.trigger.assert_called_once_with(ctx)
AssertionError: Expected: (({'event': <mock.MagicMock object at
0x1005675d0>},), {})
Called with: (({'event': <mock.Mock object at 0x10059a990>},), {})

----------------------------------------------------------------------
Ran 3 tests in 0.059s

FAILED (failures=1)


On Mon, May 20, 2013 at 11:52 AM, John Papanastasiou
<johnnypapps at gmail.com>wrote:

> Hi,
>
> I believe I have found a problem with mock.call_args_list.  My
> understanding is that for a given mock, if the function you are testing
> makes multiple calls to a function on that mock, the call_args_list is set
> to a list of the successive argument lists for each call.
>
> The problem I have is that the call_args_list for one mock is being
> replaced with the call_args_list for a second mock that is being used in
> the same function under test.
>
> To demonstrate this, I have written a script which you can just run.
>
> I have an event object which has a property which may be set to a list of
> extra event objects.  Event objects have a property called handler which
> itself has a function trigger which called with a context (a dict with a
> key 'event' set to the event instance).
>
> The function i am trying to test triggers the handler on the top level
> event, then goes through each event in the list triggering their handlers.
>  To test this function, I am making assertions about the calls to the
> respective trigger functions.
>
> The attached code demonstrates that the call_args_list for the top_level
> event (the one being called first in the function) is set to the
> call_args_list for the extra event (the one being called second).
>
> The TestCase includes two unit tests which test the calls to the top_level
> event trigger and the nested event trigger independently and these pass.
>  The third unit test, test_top_level_and_extra prints out some information
> about the mocks involved and the call_args_lists.  This output demonstrates
> the error I am seeing.  I've pasted a sample output below.
>
> Is this a defect in the mock.call_args_list or have I misunderstood the
> documentation?
>
> Any help you can give is greatly appreciated.
>
> Regards,
>
> John.
>
> Sample Output:
>
> $ ./nested_calls.py
> ..
> Mock: top_level: <mock.MagicMock object at 0x100567590>
> Call Args, top_level.handler.trigger: [(({'event': <mock.Mock object at
> 0x10059a950>},), {})]
> Mock: nested: <mock.Mock object at 0x10059a950>
> Call Args, nested.handler.trigger: [(({'event': <mock.Mock object at
> 0x10059a950>},), {})]
>
> F
> ======================================================================
> FAIL: test_top_level_and_extra (__main__.TestNestedCalls)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "./nested_calls.py", line 53, in test_top_level_and_extra
>     top_level.handler.trigger.assert_called_once_with(ctx)
> AssertionError: Expected: (({'event': <mock.MagicMock object at
> 0x100567590>},), {})
> Called with: (({'event': <mock.Mock object at 0x10059a950>},), {})
>
> ----------------------------------------------------------------------
> Ran 3 tests in 0.059s
>
> FAILED (failures=1)
>
>
>
>
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