[f] to.be.callable

[catriuspham]

Issue: #20

We will add this expectation to our code base:

expect(object).to.be.callable()

[catriuspham]

@NhanHo @hieueastagile Please take a look.

[coveralls]

Coverage increased (+0.009%) to 99.701% when pulling 908e702 on feature/callable into 2caf3a5 on master.

[hieueastagile]

I'm doing some quick googling and it looks like this is not all the cases. They are still checking for another condition to make sure it's callable. And I found out that we might be able to use callable builtin function, just need to re-check careful how this function is support among python versions. Wdyt?

My ref:
http://stackoverflow.com/questions/111234/what-is-a-callable-in-python
https://docs.python.org/2/library/functions.html#callable

[hieueastagile]

And according to my above explaination, callable is a builtin function, so it's better that we choose another name for our variable.

[NhanHo]

@hieueastagile : which python do we plan to support? Is anyone using python 3.0 or 3.1?

In python 3.x hasattr(self.actual, '__call__') is the recommended way to check for callable after callable is removed in 3.0 (https://docs.python.org/3.1/whatsnew/3.0.html#builtins). It will work with all 3.x code, but it has a bug in the case of python 2.x when the class is an old-style class (does not inherit object).

However, python 3.2 added callable function back, so the only case where using it does not work is in python 3.0 and 3.1

It seems like using callable is the best way, and if we want to support 3.0 or 3.1, there is the isinstance(foo, collections.Callable.

[hieueastagile]

@NhanHo Thanks for the very details information. I think we only support for python 2.6, 2.7, 3.4, 3.5, 3.6 (see the tox.ini for more information if you like to). So regarding your reference, I think that we should use callable instead.

[coveralls]

Coverage increased (+0.009%) to 99.701% when pulling e3140b1 on feature/callable into 2caf3a5 on master.