Fixed using modules_to_patch with modules without dir()

- check for existing dir() before calling it
- fixes #450

Author: mrbean-bremen

Diff for: CHANGES.md

@@ -6,6 +6,8 @@ The release versions are PyPi releases.
 #### New Features
 
 #### Fixes
+  * fixed using `modules_to_patch` with modules without `dir()`
+    ([#450](../../issues/450))
   * fixed recursion error on unpickling the fake file system 
     ([#445](../../issues/445))
   * allow trailing path in `add_real_directory` ([#446](../../issues/446))

Diff for: pyfakefs/fake_filesystem.py

@@ -4479,15 +4479,6 @@ class FakeIoModule(object):
     my_io_module = fake_filesystem.FakeIoModule(filesystem)
     """
 
-    @staticmethod
-    def dir():
-        """Return the list of patched function names. Used for patching
-        functions imported from the module.
-        """
-        # `open` would clash with build-in `open`, so don't patch it
-        # if imported like `from io import open`
-        return ()
-
     def __init__(self, filesystem):
         """
         Args:

Diff for: pyfakefs/fake_filesystem_unittest.py

@@ -347,12 +347,14 @@ def __init__(self, additional_skip_names=None,
             modnames = (
                 (mod_name, OS_MODULE) if mod_name == 'os' else (mod_name,)
             )
-            for fct_name in fake_module.dir():
-                self._fake_module_functions[fct_name] = (
-                    modnames,
-                    getattr(fake_module, fct_name),
-                    mod_name
-                )
+            if (hasattr(fake_module, 'dir') and
+                    inspect.isfunction(fake_module.dir)):
+                for fct_name in fake_module.dir():
+                    self._fake_module_functions[fct_name] = (
+                        modnames,
+                        getattr(fake_module, fct_name),
+                        mod_name
+                    )
         # special handling for functions in os.path
         fake_module = fake_filesystem.FakePathModule
         for fct_name in fake_module.dir():

Diff for: pyfakefs/fake_pathlib.py

@@ -635,13 +635,6 @@ class FakePathlibModule(object):
     `fake_pathlib_module = fake_filesystem.FakePathlibModule(filesystem)`
     """
 
-    @staticmethod
-    def dir():
-        """Return an empty list as `Path` methods will always be called
-        on the instances.
-        """
-        return ()
-
     def __init__(self, filesystem):
         """
         Initializes the module with the given filesystem.
@@ -685,10 +678,6 @@ class FakePathlibPathModule(object):
     """Patches `pathlib.Path` by passing all calls to FakePathlibModule."""
     fake_pathlib = None
 
-    @staticmethod
-    def dir():
-        return ()
-
     def __init__(self, filesystem):
         if self.fake_pathlib is None:
             self.__class__.fake_pathlib = FakePathlibModule(filesystem)