[Erwin]

We use the fudge module, and I have a small context manager that lets me do this:

    with autopatch(foo, bar, baz):
       foo.patch.method = something
       # first test here
       foo.patch.method = something_else

I've found that my tests usually require setting up a complex context, and then slightly varying the bit of context, so it's assuming Foo, Bar, Baz and X=1 we expect this, but if X=2 we expect that. YMMV.