Merge pull request #186 from craigcitro/openssl_import

Fall back to importing for OpenSSL detection.

oauth2client/crypt.py

@@ -38,8 +38,33 @@ class AppIdentityError(Exception):
   pass
 
 
+def _TryOpenSslImport():
+  """Import OpenSSL, avoiding the explicit import where possible.
+
+  Importing OpenSSL 0.14 can take up to 0.5s, which is a large price
+  to pay at module import time. However, it's also possible for
+  ``imp.find_module`` to fail to find the module, even when it's
+  installed. (This is the case in various exotic environments,
+  including some relevant for Google.) So we first try a fast-path,
+  and fall back to the slow import as needed.
+
+  Args:
+    None
+  Returns:
+    None
+  Raises:
+    ImportError if OpenSSL is unavailable.
+
+  """
+  try:
+    _ = imp.find_module('OpenSSL')
+    return
+  except ImportError:
+    import OpenSSL
+
+
 try:
-  _ = imp.find_module('OpenSSL')
+  _TryOpenSslImport()
 
   class OpenSSLVerifier(object):
     """Verifies the signature on a message."""

tests/test_crypt.py

@@ -60,15 +60,22 @@ class Test_pkcs12_key_as_pem(unittest.TestCase):
   def test_without_openssl(self):
     import imp
     imp_find_module = imp.find_module
+    orig_sys_path = sys.path
     def find_module(module_name):
       raise ImportError('No module named %s' % module_name)
     try:
+      for m in list(sys.modules):
+        if m.startswith('OpenSSL'):
+          sys.modules.pop(m)
+      sys.path = []
       imp.find_module = find_module
       reload(crypt)
       self.assertRaises(NotImplementedError, crypt.pkcs12_key_as_pem,
                         'FOO', 'BAR')
     finally:
+      sys.path = orig_sys_path
       imp.find_module = imp_find_module
+      import OpenSSL
       reload(crypt)
 
   def test_with_nonsense_key(self):