Fixed usage of modules_to_patch parameter

- adapted example, as the usage has slightly changed
  (full module path is now needed)
- fixes #450

Author: mrbean-bremen

CHANGES.md

@@ -8,8 +8,7 @@ The release versions are PyPi releases.
     `st_uid` and `st_gid` in new files ([#449](../../issues/449))
 
 #### Fixes
-  * fixed using `modules_to_patch` with modules without `dir()`
-    ([#450](../../issues/450))
+  * fixed using `modules_to_patch` ([#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))

docs/usage.rst

@@ -183,7 +183,7 @@ as in the following example:
       return getattr(self._locks_module, name)
 
 
-  with Patcher(modules_to_patch={'locks': FakeLocks}):
+  with Patcher(modules_to_patch={'django.core.files.locks': FakeLocks}):
       test_django_stuff()
 
 

pyfakefs/fake_filesystem_unittest.py

@@ -333,10 +333,6 @@ def __init__(self, additional_skip_names=None,
 
         if modules_to_patch is not None:
             for name, fake_module in modules_to_patch.items():
-                if '.' in name:
-                    module_name, name = name.split('.')
-                    self._class_modules.setdefault(name, []).append(
-                        module_name)
                 self._fake_module_classes[name] = fake_module
 
         # handle patching function imported separately like

pyfakefs/tests/fake_filesystem_unittest_test.py

@@ -204,10 +204,35 @@ def test_own_path_module(self):
         self.assertEqual(2, path.floor(2.5))
 
 
+class FailedPatchingTest(fake_filesystem_unittest.TestCase):
+    """Negative tests: make sure the tests for `modules_to_reload` and
+    `modules_to_patch` fail if not providing the arguments.
+    """
+
+    def setUp(self):
+        """Set up the fake file system"""
+        self.setUpPyfakefs()
+
+    @unittest.expectedFailure
+    def test_system_stat(self):
+        file_path = '/foo/bar'
+        self.fs.create_file(file_path, contents=b'test')
+        self.assertEqual(
+            4, pyfakefs.tests.import_as_example.system_stat(file_path).st_size)
+
+    @unittest.expectedFailure
+    def test_path_exists(self):
+        file_path = '/foo/bar'
+        self.fs.create_dir(file_path)
+        self.assertTrue(
+            pyfakefs.tests.import_as_example.check_if_exists4(file_path))
+
+
 class ReloadModuleTest(fake_filesystem_unittest.TestCase):
     """Make sure that reloading a module allows patching of classes not
     patched automatically.
     """
+
     def setUp(self):
         """Set up the fake file system"""
         self.setUpPyfakefs(
@@ -220,6 +245,41 @@ def test_path_exists(self):
             pyfakefs.tests.import_as_example.check_if_exists4(file_path))
 
 
+class FakeExampleModule(object):
+    """Used to patch a function that uses system-specific functions that
+    cannot be patched automatically."""
+    _orig_module = pyfakefs.tests.import_as_example
+
+    def __init__(self, fs):
+        pass
+
+    def system_stat(self, filepath):
+        return os.stat(filepath)
+
+    def __getattr__(self, name):
+        """Forwards any non-faked calls to the standard module."""
+        return getattr(self._orig_module, name)
+
+
+class PatchModuleTest(fake_filesystem_unittest.TestCase):
+    """Make sure that reloading a module allows patching of classes not
+    patched automatically.
+    """
+
+    def setUp(self):
+        """Set up the fake file system"""
+        # self.setUpPyfakefs()
+        self.setUpPyfakefs(
+            modules_to_patch={
+                'pyfakefs.tests.import_as_example': FakeExampleModule})
+
+    def test_system_stat(self):
+        file_path = '/foo/bar'
+        self.fs.create_file(file_path, contents=b'test')
+        self.assertEqual(
+            4, pyfakefs.tests.import_as_example.system_stat(file_path).st_size)
+
+
 class TestCopyOrAddRealFile(TestPyfakefsUnittestBase):
     """Tests the `fake_filesystem_unittest.TestCase.copyRealFile()` method.
     Note that `copyRealFile()` is deprecated in favor of

pyfakefs/tests/import_as_example.py

@@ -19,6 +19,8 @@
 import os as my_os
 from os import stat
 
+import sys
+
 try:
     from pathlib import Path
 except ImportError:
@@ -57,3 +59,11 @@ def check_if_exists5(filepath):
 def file_stat(filepath):
     # tests patching `stat` imported from os
     return stat(filepath)
+
+
+def system_stat(filepath):
+    if sys.platform == 'win32':
+        from nt import stat as system_stat
+    else:
+        from posix import stat as system_stat
+    return system_stat(filepath)