Unit test for improved package import semantics.

Original by Alex Coventry (in SF patch #441791), adapted to the
standard regression test framework.

Lib/test/test_pkgimport.py

+import os, sys, string, random, tempfile, unittest
+
+from test_support import run_unittest
+
+class TestImport(unittest.TestCase):
+
+    def __init__(self, *args, **kw):
+        self.package_name = 'PACKAGE_'
+        while sys.modules.has_key(self.package_name):
+            self.package_name += random.choose(string.letters)
+        self.module_name = self.package_name + '.foo'
+        unittest.TestCase.__init__(self, *args, **kw)
+
+    def remove_modules(self):
+        for module_name in (self.package_name, self.module_name):
+            if sys.modules.has_key(module_name):
+                del sys.modules[module_name]
+
+    def setUp(self):
+        self.test_dir = tempfile.mktemp()
+        os.mkdir(self.test_dir)
+        sys.path.append(self.test_dir)
+        self.package_dir = os.path.join(self.test_dir,
+                                        self.package_name)
+        os.mkdir(self.package_dir)
+        open(os.path.join(self.package_dir, '__init__.py'), 'w')
+        self.module_path = os.path.join(self.package_dir, 'foo.py')
+
+    def tearDown(self):
+        for file in os.listdir(self.package_dir):
+            os.remove(os.path.join(self.package_dir, file))
+        os.rmdir(self.package_dir)
+        os.rmdir(self.test_dir)
+        self.assertNotEqual(sys.path.count(self.test_dir), 0)
+        sys.path.remove(self.test_dir)
+        self.remove_modules()
+
+    def rewrite_file(self, contents):
+        compiled_path = self.module_path + 'c'
+        if os.path.exists(compiled_path): os.remove(compiled_path)
+        open(self.module_path, 'w').write(contents)
+    
+    def test_package_import__semantics(self):
+
+        # Generate a couple of broken modules to try importing.
+
+        # ...try loading the module when there's a SyntaxError
+        self.rewrite_file('for')
+        try: __import__(self.module_name)
+        except SyntaxError: pass
+        else: raise RuntimeError, 'Failed to induce SyntaxError'
+        self.assert_(not sys.modules.has_key(self.module_name) and
+                     not hasattr(sys.modules[self.package_name], 'foo'))
+
+        # ...make up a variable name that isn't bound in __builtins__
+        var = 'a'
+        while var in dir(__builtins__):
+            var += random.choose(string.letters)
+
+        # ...make a module that just contains that
+        self.rewrite_file(var)
+
+        try: __import__(self.module_name)
+        except NameError: pass
+        else: raise RuntimeError, 'Failed to induce NameError.'
+        module = __import__(self.module_name).foo
+
+        # ...now  change  the module  so  that  the NameError  doesn't
+        # happen
+        self.rewrite_file('%s = 1' % var)
+        reload(module)
+        self.assertEqual(getattr(module, var), 1)
+
+run_unittest(TestImport)