1 files changed, 44 insertions, 2 deletions
diff --git a/Lib/unittest/test/test_discovery.py b/Lib/unittest/test/test_discovery.py
index 1b0f08b..ad86a42 100644
--- a/Lib/unittest/test/test_discovery.py
+++ b/Lib/unittest/test/test_discovery.py
@@ -1,4 +1,5 @@
 import os
+import re
 import sys
 
 import unittest
@@ -53,8 +54,9 @@ class TestDiscovery(unittest.TestCase):
         loader._get_module_from_name = lambda path: path + ' module'
         loader.loadTestsFromModule = lambda module: module + ' tests'
 
-        loader._top_level_dir = '/foo'
-        suite = list(loader._find_tests('/foo', 'test*.py'))
+        top_level = os.path.abspath('/foo')
+        loader._top_level_dir = top_level
+        suite = list(loader._find_tests(top_level, 'test*.py'))
 
         expected = [name + ' module tests' for name in
                     ('test1', 'test2')]
@@ -294,6 +296,46 @@ class TestDiscovery(unittest.TestCase):
         self.assertTrue(program.failfast)
         self.assertTrue(program.catchbreak)
 
+    def test_detect_module_clash(self):
+        class Module(object):
+            __file__ = 'bar/foo.py'
+        sys.modules['foo'] = Module
+        full_path = os.path.abspath('foo')
+        original_listdir = os.listdir
+        original_isfile = os.path.isfile
+        original_isdir = os.path.isdir
+
+        def cleanup():
+            os.listdir = original_listdir
+            os.path.isfile = original_isfile
+            os.path.isdir = original_isdir
+            del sys.modules['foo']
+            if full_path in sys.path:
+                sys.path.remove(full_path)
+        self.addCleanup(cleanup)
+
+        def listdir(_):
+            return ['foo.py']
+        def isfile(_):
+            return True
+        def isdir(_):
+            return True
+        os.listdir = listdir
+        os.path.isfile = isfile
+        os.path.isdir = isdir
+
+        loader = unittest.TestLoader()
+
+        mod_dir = os.path.abspath('bar')
+        expected_dir = os.path.abspath('foo')
+        msg = re.escape(r"'foo' module incorrectly imported from %r. Expected %r. "
+                "Is this module globally installed?" % (mod_dir, expected_dir))
+        self.assertRaisesRegexp(
+            ImportError, '^%s$' % msg, loader.discover,
+            start_dir='foo', pattern='foo.py'
+        )
+        self.assertEqual(sys.path[0], full_path)
+
 
 if __name__ == '__main__':
     unittest.main()