This library was inspired by multiple different mocking frameworks I was working with. They all come from completely different worlds such as Java, JavaScript, C++ and C#.

Here is a simple example how mocking of a time.time() can be done:

import vmock
import time
v = vmock.VMock()
time_mock = v.mock_method(time, 'time')
time_mock().returns(1)
<vmock.mockcallaction.MockCallAction object at 0x103ca1780>
time_mock().returns(2).twice()
<vmock.mockcallaction.MockCallAction object at 0x103ca1eb8>
v.replay()
time.time()
1
time.time()
2
time.time()
2
v.verify()
v.tear_down()
time.time()
1408850749.91605

Even more, VMock can create snapshots of class definitions and object generating virtual code for them, thus you don't need to mock each method separately. Even more, it mimics their interface so, any interface change will result in not working test if there is a call mismatch.