| # -*- test-case-name: twisted.test.test_monkey -*- |
| |
| # Copyright (c) 2007 Twisted Matrix Laboratories. |
| # See LICENSE for details. |
| |
| |
| class MonkeyPatcher(object): |
| """ |
| Cover up attributes with new objects. Neat for monkey-patching things for |
| unit-testing purposes. |
| """ |
| |
| def __init__(self, *patches): |
| # List of patches to apply in (obj, name, value). |
| self._patchesToApply = [] |
| # List of the original values for things that have been patched. |
| # (obj, name, value) format. |
| self._originals = [] |
| for patch in patches: |
| self.addPatch(*patch) |
| |
| |
| def addPatch(self, obj, name, value): |
| """ |
| Add a patch so that the attribute C{name} on C{obj} will be assigned to |
| C{value} when C{patch} is called or during C{runWithPatches}. |
| |
| You can restore the original values with a call to restore(). |
| """ |
| self._patchesToApply.append((obj, name, value)) |
| |
| |
| def _alreadyPatched(self, obj, name): |
| """ |
| Has the C{name} attribute of C{obj} already been patched by this |
| patcher? |
| """ |
| for o, n, v in self._originals: |
| if (o, n) == (obj, name): |
| return True |
| return False |
| |
| |
| def patch(self): |
| """ |
| Apply all of the patches that have been specified with L{addPatch}. |
| Reverse this operation using L{restore}. |
| """ |
| for obj, name, value in self._patchesToApply: |
| if not self._alreadyPatched(obj, name): |
| self._originals.append((obj, name, getattr(obj, name))) |
| setattr(obj, name, value) |
| |
| |
| def restore(self): |
| """ |
| Restore all original values to any patched objects. |
| """ |
| while self._originals: |
| obj, name, value = self._originals.pop() |
| setattr(obj, name, value) |
| |
| |
| def runWithPatches(self, f, *args, **kw): |
| """ |
| Apply each patch already specified. Then run the function f with the |
| given args and kwargs. Restore everything when done. |
| """ |
| self.patch() |
| try: |
| return f(*args, **kw) |
| finally: |
| self.restore() |
