Fix V3 credential behavior, documentation

Fixing V3 credential behavior so that contradicting parameter combinations
do not result in unpredictable behavior.  Updating accounts.yaml.sample
file to reference the correct location of the credentials
classes and to describe the updated behavior of Identity V3 attributes.

Change-Id: I29efe778afcb1e4a55dffd6a8ed8212d62a4dd15
diff --git a/tempest/lib/auth.py b/tempest/lib/auth.py
index 2d20a0b..71c4f4f 100644
--- a/tempest/lib/auth.py
+++ b/tempest/lib/auth.py
@@ -622,6 +622,9 @@
         return None not in (self.username, self.password)
 
 
+COLLISIONS = [('project_name', 'tenant_name'), ('project_id', 'tenant_id')]
+
+
 class KeystoneV3Credentials(Credentials):
     """Credentials suitable for the Keystone Identity V3 API"""
 
@@ -630,6 +633,16 @@
                   'project_name', 'tenant_id', 'tenant_name', 'user_domain_id',
                   'user_domain_name', 'user_id']
 
+    def _apply_credentials(self, attr):
+        for (key1, key2) in COLLISIONS:
+            val1 = attr.get(key1)
+            val2 = attr.get(key2)
+            if val1 and val2 and val1 != val2:
+                msg = ('Cannot have conflicting values for %s and %s' %
+                       (key1, key2))
+                raise exceptions.InvalidCredentials(msg)
+        super(KeystoneV3Credentials, self)._apply_credentials(attr)
+
     def __setattr__(self, key, value):
         parent = super(KeystoneV3Credentials, self)
         # for tenant_* set both project and tenant
@@ -657,8 +670,10 @@
                 parent.__setattr__('user_domain_name', value)
         # support domain_name coming from config
         if key == 'domain_name':
-            parent.__setattr__('user_domain_name', value)
-            parent.__setattr__('project_domain_name', value)
+            if self.user_domain_name is None:
+                parent.__setattr__('user_domain_name', value)
+            if self.project_domain_name is None:
+                parent.__setattr__('project_domain_name', value)
         # finally trigger default behaviour for all attributes
         parent.__setattr__(key, value)
 
diff --git a/tempest/tests/lib/test_auth.py b/tempest/tests/lib/test_auth.py
index ebcfe82..6a01490 100644
--- a/tempest/tests/lib/test_auth.py
+++ b/tempest/tests/lib/test_auth.py
@@ -530,3 +530,43 @@
 
         expected = 'http://fake_url/v3'
         self._test_base_url_helper(expected, filters, ('token', auth_data))
+
+
+class TestKeystoneV3Credentials(base.TestCase):
+    def testSetAttrUserDomain(self):
+        creds = auth.KeystoneV3Credentials()
+        creds.user_domain_name = 'user_domain'
+        creds.domain_name = 'domain'
+        self.assertEqual('user_domain', creds.user_domain_name)
+        creds = auth.KeystoneV3Credentials()
+        creds.domain_name = 'domain'
+        creds.user_domain_name = 'user_domain'
+        self.assertEqual('user_domain', creds.user_domain_name)
+
+    def testSetAttrProjectDomain(self):
+        creds = auth.KeystoneV3Credentials()
+        creds.project_domain_name = 'project_domain'
+        creds.domain_name = 'domain'
+        self.assertEqual('project_domain', creds.user_domain_name)
+        creds = auth.KeystoneV3Credentials()
+        creds.domain_name = 'domain'
+        creds.project_domain_name = 'project_domain'
+        self.assertEqual('project_domain', creds.project_domain_name)
+
+    def testProjectTenantNoCollision(self):
+        creds = auth.KeystoneV3Credentials(tenant_id='tenant')
+        self.assertEqual('tenant', creds.project_id)
+        creds = auth.KeystoneV3Credentials(project_id='project')
+        self.assertEqual('project', creds.tenant_id)
+        creds = auth.KeystoneV3Credentials(tenant_name='tenant')
+        self.assertEqual('tenant', creds.project_name)
+        creds = auth.KeystoneV3Credentials(project_name='project')
+        self.assertEqual('project', creds.tenant_name)
+
+    def testProjectTenantCollision(self):
+        attrs = {'tenant_id': 'tenant', 'project_id': 'project'}
+        self.assertRaises(
+            exceptions.InvalidCredentials, auth.KeystoneV3Credentials, **attrs)
+        attrs = {'tenant_name': 'tenant', 'project_name': 'project'}
+        self.assertRaises(
+            exceptions.InvalidCredentials, auth.KeystoneV3Credentials, **attrs)