Add back argument use_dynamic_patch

- can be used for cases where dynamic patching causes problems

CHANGES.md

@@ -7,6 +7,8 @@ The released versions correspond to PyPI releases.
 * fixes handling of unhashable modules which cannot be cached (see [#923](../../issues/923))
 * reload modules loaded by the dynamic patcher instead of removing them - sometimes they may
   not be reloaded automatically (see [#932](../../issues/932))
+* add back argument `use_dynamic_patch` as a fallback for similar problems
+
 
 ## [Version 5.3.2](https://pypi.python.org/pypi/pyfakefs/5.3.2) (2023-11-30)
 Bugfix release.

docs/usage.rst

@@ -657,6 +657,13 @@ If you want to clear the cache just for a specific test instead, you can call
       fs.clear_cache()
       ...
 
+use_dynamic_patch
+~~~~~~~~~~~~~~~~~
+If ``True`` (the default), dynamic patching after setup is used (for example
+for modules loaded locally inside of functions).
+Can be switched off if it causes unwanted side effects, which happened at least in
+once instance while testing a django project.
+
 
 .. _convenience_methods:
 

pyfakefs/fake_filesystem_unittest.py

@@ -105,6 +105,7 @@ def patchfs(
     patch_open_code: PatchMode = PatchMode.OFF,
     patch_default_args: bool = False,
     use_cache: bool = True,
+    use_dynamic_patch: bool = True,
 ) -> Callable:
     """Convenience decorator to use patcher with additional parameters in a
     test function.
@@ -132,6 +133,7 @@ def wrapped(*args, **kwargs):
                 patch_open_code=patch_open_code,
                 patch_default_args=patch_default_args,
                 use_cache=use_cache,
+                use_dynamic_patch=use_dynamic_patch,
             ) as p:
                 args = list(args)
                 args.append(p.fs)
@@ -167,6 +169,7 @@ def load_doctests(
     use_known_patches: bool = True,
     patch_open_code: PatchMode = PatchMode.OFF,
     patch_default_args: bool = False,
+    use_dynamic_patch: bool = True,
 ) -> TestSuite:  # pylint:disable=unused-argument
     """Load the doctest tests for the specified module into unittest.
         Args:
@@ -186,6 +189,7 @@ def load_doctests(
             use_known_patches=use_known_patches,
             patch_open_code=patch_open_code,
             patch_default_args=patch_default_args,
+            use_dynamic_patch=use_dynamic_patch,
             is_doc_test=True,
         )
     assert Patcher.DOC_PATCHER is not None
@@ -312,6 +316,7 @@ def setUpClassPyfakefs(
         patch_open_code: PatchMode = PatchMode.OFF,
         patch_default_args: bool = False,
         use_cache: bool = True,
+        use_dynamic_patch: bool = True,
     ) -> None:
         """Similar to :py:func:`setUpPyfakefs`, but as a class method that
         can be used in `setUpClass` instead of in `setUp`.
@@ -349,6 +354,7 @@ def setUpClassPyfakefs(
             patch_open_code=patch_open_code,
             patch_default_args=patch_default_args,
             use_cache=use_cache,
+            use_dynamic_patch=use_dynamic_patch,
         )
 
         Patcher.PATCHER.setUp()
@@ -513,6 +519,7 @@ def __init__(
         patch_open_code: PatchMode = PatchMode.OFF,
         patch_default_args: bool = False,
         use_cache: bool = True,
+        use_dynamic_patch: bool = True,
         is_doc_test: bool = False,
     ) -> None:
         """
@@ -545,6 +552,9 @@ def __init__(
                 cached between tests for performance reasons. As this is a new
                 feature, this argument allows to turn it off in case it
                 causes any problems.
+           use_dynamic_patch: If `True`, dynamic patching after setup is used
+                (for example for modules loaded locally inside of functions).
+                Can be switched off if it causes unwanted side effects.
         """
         self.is_doc_test = is_doc_test
         if is_doc_test:
@@ -582,6 +592,7 @@ def __init__(
             self.modules_to_reload.extend(modules_to_reload)
         self.patch_default_args = patch_default_args
         self.use_cache = use_cache
+        self.use_dynamic_patch = True
 
         if use_known_patches:
             from pyfakefs.patched_packages import (
@@ -914,6 +925,9 @@ def start_patching(self) -> None:
             for module in self.modules_to_reload:
                 if sys.modules.get(module.__name__) is module:
                     reload(module)
+            if not self.use_dynamic_patch:
+                self._dyn_patcher.cleanup()
+                sys.meta_path.pop(0)
 
     def patch_functions(self) -> None:
         assert self._stubs is not None
@@ -989,7 +1003,7 @@ def stop_patching(self, temporary=False) -> None:
             if self._stubs:
                 self._stubs.smart_unset_all()
             self.unset_defaults()
-            if self._dyn_patcher:
+            if self.use_dynamic_patch and self._dyn_patcher:
                 self._dyn_patcher.cleanup()
                 sys.meta_path.pop(0)