[TIP] Making mock objects that call the original function

[Kevin Tran]

Yes!  The wraps parameter was what I was looking for.

I tried passing wraps=True into ``patch()`` as you suggested, but this resulted in an TypeError because True is not callable:
Traceback (most recent call last):
  File "/Users/haitran/repos/soalike_project/eggs/mock-1.0.1-py2.7.egg/mock.py", line 1031, in _mock_call
    return self._mock_wraps(*args, **kwargs)
TypeError: 'bool' object is not callable

Anyway the wraps parameter is good balance between explicitness and convenience for me.  Thanks!

On May 17, 2013, at 3:15 AM, Michael Foord <fuzzyman at voidspace.org.uk> wrote:

> 
> On 17 May 2013, at 00:46, Kevin Tran <hekevintran at gmail.com> wrote:
> 
>> The mock objects in the Jasmine testing framework have a `andCallthrough()` method.  This allows you have a mock that when called, calls the original function.  An example:
>> 
>>   describe("A spy, when configured to call through", function() {
>>     var foo, bar, fetchedBar;
>> 
>>     beforeEach(function() {
>>       foo = {
>>         setBar: function(value) {
>>           bar = value;
>>         },
>>         getBar: function() {
>>           return bar;
>>         }
>>       };
>> 
>>       spyOn(foo, 'getBar').andCallThrough();
>> 
>>       foo.setBar(123);
>>       fetchedBar = foo.getBar();
>>     });
>> 
>>     it("tracks that the spy was called", function() {
>>       expect(foo.getBar).toHaveBeenCalled();
>>     });
>> 
>>     it("should not effect other functions", function() {
>>       expect(bar).toEqual(123);
>>     });
>> 
>>     it("when called returns the requested value", function() {
>>       expect(fetchedBar).toEqual(123);
>>     });
>>   });
>> 
>> The only way I know how to do this in the Python mock library (http://www.voidspace.org.uk/python/mock/) is by setting the original function manually:
>> 
>>   with patch('my_project.forms.create_user') as mock_create_user:
>>       mock_create_user.side_effect = create_user
>>       client.post('/signup/', data)
>>       self.assertEqual(1, mock_create_user.call_count)
>>       self.assertEqual(1, User.objects.count())
>> 
>> Is there a better built-in way to do this?
> 
> 
> You can use the "wraps" keyword argument.
> 
>>>> from mock import Mock
>>>> def foo():
> ...     print 'Called'
> ...     
>>>> m = Mock(wraps=foo)
>>>> 
>>>> m()
> Called
> 
> I believe that patch takes a "wraps=True" keyword argument to do this automatically for you.
> 
> All the best,
> 
> Michael Foord
> 
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> 
> 
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> 
> 
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