Styjun

I am dealing with a codebase that has a large number of modules which instantiate database connections, read from registry, etc when they are imported. (Code in a main function or in a class, but in the global scope). I will call these modules 'bad modules'.

For reasons outside of the scope of this question, I need to be able to import other libraries ('good modules') relying on these libraries without failing, and my environment is such that these libraries will fail on import.

At the moment, I am doing this, where 'idmlib' is a bad module, and all of its children are bad modules:

sys.modules['idmlib'] = MagicMock()
sys.modules['idmlib.idmobject'] = Mock()
sys.modules['idmlib.idapi'] = Mock()
sys.modules['idmlib.database'] = Mock()
sys.modules['idmlib.plugins'] = Mock()
sys.modules['idmlib.plugins.authmod'] = Mock()

... other code ...

This works fine, but I need to predict every single child, grandchild, etc of idmlib which will be imported.

Instead, I would like to generically mock out idmlib and all of its sub-modules ahead of time, without needing to know what all of those sub-modules are.

Is there any way to make sys.modules['idmlib'] into a MagicMock whose sub-modules are all also MagicMocks?

My first thought is to have sys.modules be a mock wrapping the original sys.modules, which has some alternate behavior if it's being checked for something starting with 'idmlib' and otherwise just interacting with the original dictionary.

Unfortunately, this causes infinite recursion.

original_sys_modules = sys.modules
mock_sys_modules = MagicMock(wraps=original_sys_modules)


sys.modules = mock_sys_modules
import psutil

Error:

Traceback (most recent call last):
 File "dryrun-script.py", line 26, in <module>
 import psutil
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 File "C:Usersdanie01.AD.virtualenvsrobotframework-O8sDx-L-libsite-packagespsutil__init__.py", line 41, in <module>
 from . import _common
 ...