Comments on: Python Is Mocking Me: A Ruby Programmer’s Adventures With Python/Mox

By: Brain Matters » Blog Archive » Mocking HTTP request and response with Python and Mox

Thu, 01 Oct 2009 13:55:59 +0000

[...] Tim, has written an excellent post on his adventures as a Ruby programmer getting up to speed on testing and mocking in Python using Mox. You should read [...]

By: Agora Games

Agora Games — Thu, 28 May 2009 12:27:51 +0000

Finally went back and cleaned up the formatting a bit. Also, a much more elegant way to mock local object construction was shown to me recently. It’s described in this post in the mox google group.

The summary is that we should just be using:
m.StubOutWithMock(my_module, “MyClass”, use_mock_anything = True)

Since classes, modules, etc, can be reassigned just as easily as methods we can easily substitute a MockAnything instance for our class. Much nicer! The trick is actually in the use_mock_anything keyword arg (which doesn’t seem to be documented anywhere!). This causes mox to replace the class with a MockAnything instance whereas normally it would replace it with a (non-callable) MockObject.

I believe this also solves the old-style class problem that was discussed previously (although I haven’t tried).

By: Vitaly

Vitaly — Fri, 20 Mar 2009 04:47:51 +0000

Hey thanks for the article it was very helpful. Just a note that the code formating is broken and all the code is left justified so it makes the code kinda hard to read.

By: Tim

Tim — Fri, 06 Mar 2009 14:46:25 +0000

Hey K,
I noticed this problem the other day too. It’s basically an issue with new-style vs. old-style classes. Old-style classes don’t use the same __new__ -> __init__ step that new-style classes do. In my case the class I was trying to mock was in my code so I just changed it to inherit from object and make it a new-style class.

Unfortunately, you don’t really have that option with HTTPConnection. One thing you might try is creating a wrapper for HTTPConnection so you can treat it like a new-style class.

class MyHTTPConnection(httplib.HTTPConnection, object): pass

Then you can mock __new__ on MyHTTPConnection instead.

Admittedly the solution isn’t ideal but, in my quick test, it did seem to work. I need to do a bit more reading on old-style classes and I’ll get back to you if I find a better (more direct) solution.

By: K. Adam Christensen

K. Adam Christensen — Thu, 05 Mar 2009 05:27:22 +0000

Hi.

I am trying to mock out httplib.HTTPConnection, however when I try self.mox.StubOutWithMock(httplib.HTTPConnection, “__new__”), I get an AttributeError: class HTTPConnection has no attribute ‘__new__’.

Would you happen to have any ideas? Perhaps a work around?

By: K. Adam Christensen

K. Adam Christensen — Wed, 04 Mar 2009 04:26:54 +0000

Thank you so much for this article. This is exactly what I need! Cheers!

By: Tim

Tim — Wed, 25 Feb 2009 13:35:34 +0000

A couple of other misc items:

* There’s no way to mock statements (as far as I know). This means you can’t mock things like print and exec.

* I’ve yet to try mocking private methods (double underscore) but I think it’s possible as nothing is truly private in Python. There’s a discussion here (http://stackoverflow.com/questions/70528/why-are-pythons-private-methods-not-actually-private) of how private methods can be accessed. I’d imagine the same rules apply to mocking. That being said, for clarity, I’d recommend using private by convention (single underscore) except in special cases.