Allow passing None for username in v2.Password

None must be an acceptable parameter for username in password due to
tests in other libraries, however we should still raise an error if
neither username or user_id is passed. Use and check a sentinel value
instead of None.

Change-Id: Id61cfd1423afa8f9dd964fda278f4fab40887512
Closes-Bug: #1361444

keystoneclient/auth/identity/v2.py

@@ -95,11 +95,14 @@ class Auth(base.BaseIdentityPlugin):
         """
 
 
+_NOT_PASSED = object()
+
+
 class Password(Auth):
 
     @utils.positional(4)
-    def __init__(self, auth_url, username=None, password=None, user_id=None,
-                 **kwargs):
+    def __init__(self, auth_url, username=_NOT_PASSED, password=None,
+                 user_id=_NOT_PASSED, **kwargs):
         """A plugin for authenticating with a username and password.
 
         A username or user_id must be provided.
@@ -113,10 +116,15 @@ class Password(Auth):
         """
         super(Password, self).__init__(auth_url, **kwargs)
 
-        if not (user_id or username):
+        if username is _NOT_PASSED and user_id is _NOT_PASSED:
             msg = 'You need to specify either a username or user_id'
             raise TypeError(msg)
 
+        if username is _NOT_PASSED:
+            username = None
+        if user_id is _NOT_PASSED:
+            user_id = None
+
         self.user_id = user_id
         self.username = username
         self.password = password

keystoneclient/tests/auth/test_identity_v2.py

@@ -100,6 +100,7 @@ class V2IdentityPlugin(utils.TestCase):
         self.stub_auth(json=self.TEST_RESPONSE_DICT)
         a = v2.Password(self.TEST_URL, username=self.TEST_USER,
                         password=self.TEST_PASS)
+        self.assertIsNone(a.user_id)
         s = session.Session(a)
         s.get_token()
 
@@ -114,6 +115,7 @@ class V2IdentityPlugin(utils.TestCase):
         self.stub_auth(json=self.TEST_RESPONSE_DICT)
         a = v2.Password(self.TEST_URL, user_id=self.TEST_USER,
                         password=self.TEST_PASS)
+        self.assertIsNone(a.username)
         s = session.Session(a)
         s.get_token()
 
@@ -128,6 +130,7 @@ class V2IdentityPlugin(utils.TestCase):
         self.stub_auth(json=self.TEST_RESPONSE_DICT)
         a = v2.Password(self.TEST_URL, username=self.TEST_USER,
                         password=self.TEST_PASS, tenant_id=self.TEST_TENANT_ID)
+        self.assertIsNone(a.user_id)
         s = session.Session(a)
         s.get_token()
 
@@ -141,6 +144,7 @@ class V2IdentityPlugin(utils.TestCase):
         self.stub_auth(json=self.TEST_RESPONSE_DICT)
         a = v2.Password(self.TEST_URL, user_id=self.TEST_USER,
                         password=self.TEST_PASS, tenant_id=self.TEST_TENANT_ID)
+        self.assertIsNone(a.username)
         s = session.Session(a)
         s.get_token()