Use mock to patch msvc9compiler.Reg.

setuptools/tests/test_msvc9compiler.py

@@ -11,6 +11,7 @@ import tempfile
 import distutils.errors
 
 import pytest
+import mock
 
 from . import contexts
 
@@ -19,48 +20,41 @@ __import__('setuptools')
 
 pytest.importorskip("distutils.msvc9compiler")
 
-class MockReg:
-    """Mock for distutils.msvc9compiler.Reg. We patch it
-    with an instance of this class that mocks out the
-    functions that access the registry.
-    """
-
-    def __init__(self, hkey_local_machine={}, hkey_current_user={}):
-        self.hklm = hkey_local_machine
-        self.hkcu = hkey_current_user
-
-    def __enter__(self):
-        self.original_read_keys = distutils.msvc9compiler.Reg.read_keys
-        self.original_read_values = distutils.msvc9compiler.Reg.read_values
-
-        _winreg = getattr(distutils.msvc9compiler, '_winreg', None)
-        winreg = getattr(distutils.msvc9compiler, 'winreg', _winreg)
 
-        hives = {
-            winreg.HKEY_CURRENT_USER: self.hkcu,
-            winreg.HKEY_LOCAL_MACHINE: self.hklm,
-        }
+def mock_reg(hkcu=None, hklm=None):
+    """
+    Return a mock for distutils.msvc9compiler.Reg, patched
+    to mock out the functions that access the registry.
+    """
 
-        def read_keys(cls, base, key):
-            """Return list of registry keys."""
-            hive = hives.get(base, {})
-            return [k.rpartition('\\')[2]
-                    for k in hive if k.startswith(key.lower())]
+    _winreg = getattr(distutils.msvc9compiler, '_winreg', None)
+    winreg = getattr(distutils.msvc9compiler, 'winreg', _winreg)
 
-        def read_values(cls, base, key):
-            """Return dict of registry keys and values."""
-            hive = hives.get(base, {})
-            return dict((k.rpartition('\\')[2], hive[k])
-                        for k in hive if k.startswith(key.lower()))
+    hives = {
+        winreg.HKEY_CURRENT_USER: hkcu or {},
+        winreg.HKEY_LOCAL_MACHINE: hklm or {},
+    }
 
-        distutils.msvc9compiler.Reg.read_keys = classmethod(read_keys)
-        distutils.msvc9compiler.Reg.read_values = classmethod(read_values)
+    @classmethod
+    def read_keys(cls, base, key):
+        """Return list of registry keys."""
+        hive = hives.get(base, {})
+        return [
+            k.rpartition('\\')[2]
+            for k in hive if k.startswith(key.lower())
+        ]
 
-        return self
+    @classmethod
+    def read_values(cls, base, key):
+        """Return dict of registry keys and values."""
+        hive = hives.get(base, {})
+        return dict(
+            (k.rpartition('\\')[2], hive[k])
+            for k in hive if k.startswith(key.lower())
+        )
 
-    def __exit__(self, exc_type, exc_value, exc_tb):
-        distutils.msvc9compiler.Reg.read_keys = self.original_read_keys
-        distutils.msvc9compiler.Reg.read_values = self.original_read_values
+    return mock.patch.multiple(distutils.msvc9compiler.Reg,
+        read_keys=read_keys, read_values=read_values)
 
 
 class TestMSVC9Compiler:
@@ -75,7 +69,7 @@ class TestMSVC9Compiler:
         # No registry entries or environment variable means we should
         # not find anything
         with contexts.environment(VS90COMNTOOLS=None):
-            with MockReg():
+            with mock_reg():
                 assert find_vcvarsall(9.0) is None
 
                 expected = distutils.errors.DistutilsPlatformError
@@ -96,29 +90,33 @@ class TestMSVC9Compiler:
         open(mock_vcvarsall_bat_2, 'w').close()
         try:
             # Ensure we get the current user's setting first
-            with MockReg(
-                hkey_current_user={key_32: mock_installdir_1},
-                hkey_local_machine={
+            reg = mock_reg(
+                hkcu={
+                    key_32: mock_installdir_1,
+                },
+                hklm={
                     key_32: mock_installdir_2,
                     key_64: mock_installdir_2,
-                }
-            ):
+                },
+            )
+            with reg:
                 assert mock_vcvarsall_bat_1 == find_vcvarsall(9.0)
 
             # Ensure we get the local machine value if it's there
-            with MockReg(hkey_local_machine={key_32: mock_installdir_2}):
+            with mock_reg(hklm={key_32: mock_installdir_2}):
                 assert mock_vcvarsall_bat_2 == find_vcvarsall(9.0)
 
             # Ensure we prefer the 64-bit local machine key
             # (*not* the Wow6432Node key)
-            with MockReg(
-                hkey_local_machine={
+            reg = mock_reg(
+                hklm={
                     # This *should* only exist on 32-bit machines
                     key_32: mock_installdir_1,
                     # This *should* only exist on 64-bit machines
                     key_64: mock_installdir_2,
                 }
-            ):
+            )
+            with reg:
                 assert mock_vcvarsall_bat_1 == find_vcvarsall(9.0)
         finally:
             shutil.rmtree(mock_installdir_1)