MObject

M(ock)Object is a tiny library to construct objects and object trees for mocking and stubbing.

It is not meant as a replacement for mock frameworks but rather as a complement.

The basics, dynamic object specification

Creating a new object is easy.

>>> from mobject import MObject
>>> o = MObject(a=1, b=2)
>>> o.a
1
>>> o.b
2
>>> o
MObject(a=1, b=2)

There's also support for easy specification of nested objects through the __ syntax.

>>> from mobject import MObject
>>> o = MObject(a__b=1, a__c=2)
>>> o.a.b
1
>>> o.a.c
2
>>> o
MObject(a__b=1, a__c=2)

The above can also be written using a dict or any other Mapping as argument.

>>> from mobject import MObject
>>> o = MObject({'a': {'b': 1, 'c': 2}})
>>> o.a.b
1
>>> o.a.c
2
>>> o
MObject(a__b=1, a__c=2)

To save some letters there is also a short hand:

>>> from mobject import *
>>> mob(a=1) == MObject(a=1)
True

Classes for object specification

The examples from above can also be specified as classes which, when instantiated, produce equivalent objects. Attributes can also be overridden by providing values at instantiation.

>>> from mobject import MObject
>>> class MyMObject(MObject):
...     a = 1
...     b = 2
...
>>> o = MyMObject()
>>> o.a, o.b
(1, 2)
>>> MyMObject(a=3)
MyMObject(a=3, b=2)

Class specification of nested objects is also supported in two different forms.

>>> class MyNestedMObject1(MObject):
...     a = 1
...     b__c = 2
...
>>> class MyNestedMObject2(MObject):
...     a = 1
...     class b(MObject):
...         c = 2
>>> MyNestedMObject1() == MyNestedMObject2()
True
>>> MyNestedMObject1() == MyNestedMObject2(b__c=3)
False

Adding behaviour

You can add behaviour to your objects by assigning callable objects.

>>> o = MObject(fn=lambda x: x + 1)
>>> o.fn(1)
2

Nothing particular so far. Here's a special twist though. If your callable takes a first argument named 'self' it will get access to the object it is defined for.

>>> o = MObject(a=1, fn=lambda self, x: self.a + x, b__a=3, b__fn=lambda self, x: self.a + x)
>>> o.fn(1)
2
>>> o.b.fn(1)
4

Object comparison

Objects created with MObject can be compared to any other object. Two objects are equal if all non callable properties of the objects are equal. Callables are excluded from comparison. MObjects also define set like comparison operations. This is very convenient when you only want to compare a subset of an objects properties to that specified by the MObject.

The following examples will hopefully bring clarity to how comparisons work.

>>> class Foo(object):  # Regular class
...     def __init__(self):
...         self.a = 1
...         self.b = 2
...
>>> MObject(a=1, b=2) == Foo()
True
>>> MObject(a=1, b=3) == Foo()
False
>>> MObject(a=1) < Foo()
True
>>> MObject(a=2) < Foo()
False
>>> MObject(a=1, b=2, c=3) > Foo()
True
>>> MObject(a=2, b=2, c=3) > Foo()
False

Installation

pip install mobject

Compatibility

MObject has been verified to work on Python 2.7, Python 3.4 and PyPy.

Contributing

If you experience problems please log them on GitHub. If you want to contribute code, please fork the code and submit a pull request.