1 files changed, 21 insertions, 2 deletions
diff --git a/Lib/test/test_importlib/fixtures.py b/Lib/test/test_importlib/fixtures.py
index 0b4ce18..695c92a 100644
--- a/Lib/test/test_importlib/fixtures.py
+++ b/Lib/test/test_importlib/fixtures.py
@@ -47,14 +47,28 @@ def tempdir_as_cwd():
             yield tmp
 
 
-class SiteDir:
+@contextlib.contextmanager
+def install_finder(finder):
+    sys.meta_path.append(finder)
+    try:
+        yield
+    finally:
+        sys.meta_path.remove(finder)
+
+
+class Fixtures:
     def setUp(self):
         self.fixtures = ExitStack()
         self.addCleanup(self.fixtures.close)
+
+
+class SiteDir(Fixtures):
+    def setUp(self):
+        super(SiteDir, self).setUp()
         self.site_dir = self.fixtures.enter_context(tempdir())
 
 
-class OnSysPath:
+class OnSysPath(Fixtures):
     @staticmethod
     @contextlib.contextmanager
     def add_sys_path(dir):
@@ -198,3 +212,8 @@ def build_files(file_defs, prefix=pathlib.Path()):
 def DALS(str):
     "Dedent and left-strip"
     return textwrap.dedent(str).lstrip()
+
+
+class NullFinder:
+    def find_module(self, name):
+        pass