add both v2 and v3 tests for get specified extension

this add tests for getting specified extension info both against
on nova v2 and v3 api.

Partially implements blueprint nova-v3-api-tests

Change-Id: I9e254069db737d3eb9088475d7272d8aa79b1bd1
diff --git a/tempest/api/compute/test_extensions.py b/tempest/api/compute/test_extensions.py
index 8f1e446..b0bffc4 100644
--- a/tempest/api/compute/test_extensions.py
+++ b/tempest/api/compute/test_extensions.py
@@ -17,18 +17,31 @@
 
 
 from tempest.api.compute import base
-from tempest.test import attr
+from tempest import test
+import testtools
 
 
 class ExtensionsTestJSON(base.BaseV2ComputeTest):
     _interface = 'json'
 
-    @attr(type='gate')
+    @testtools.skipIf(not test.is_extension_enabled('os-consoles', 'compute'),
+                      'os-consoles extension not enabled.')
+    @test.attr(type='gate')
     def test_list_extensions(self):
         # List of all extensions
         resp, extensions = self.extensions_client.list_extensions()
         self.assertIn("extensions", extensions)
         self.assertEqual(200, resp.status)
+        self.assertTrue(self.extensions_client.is_enabled("Consoles"))
+
+    @testtools.skipIf(not test.is_extension_enabled('os-consoles', 'compute'),
+                      'os-consoles extension not enabled.')
+    @test.attr(type='gate')
+    def test_get_extension(self):
+        # get the specified extensions
+        resp, extension = self.extensions_client.get_extension('os-consoles')
+        self.assertEqual(200, resp.status)
+        self.assertEqual('os-consoles', extension['alias'])
 
 
 class ExtensionsTestXML(ExtensionsTestJSON):
diff --git a/tempest/api/compute/v3/test_extensions.py b/tempest/api/compute/v3/test_extensions.py
index d7269d1..2affd86 100644
--- a/tempest/api/compute/v3/test_extensions.py
+++ b/tempest/api/compute/v3/test_extensions.py
@@ -17,18 +17,26 @@
 
 
 from tempest.api.compute import base
-from tempest.test import attr
+from tempest import test
 
 
 class ExtensionsV3TestJSON(base.BaseV3ComputeTest):
     _interface = 'json'
 
-    @attr(type='gate')
+    @test.attr(type='gate')
     def test_list_extensions(self):
         # List of all extensions
         resp, extensions = self.extensions_client.list_extensions()
         self.assertIn("extensions", extensions)
         self.assertEqual(200, resp.status)
+        self.assertTrue(self.extensions_client.is_enabled("Consoles"))
+
+    @test.attr(type='gate')
+    def test_get_extension(self):
+        # get the specified extensions
+        resp, extension = self.extensions_client.get_extension('servers')
+        self.assertEqual(200, resp.status)
+        self.assertEqual('servers', extension['alias'])
 
 
 class ExtensionsV3TestXML(ExtensionsV3TestJSON):
diff --git a/tempest/services/compute/json/extensions_client.py b/tempest/services/compute/json/extensions_client.py
index ce46a9b..ad5354c 100644
--- a/tempest/services/compute/json/extensions_client.py
+++ b/tempest/services/compute/json/extensions_client.py
@@ -37,3 +37,8 @@
         _, extensions = self.list_extensions()
         exts = extensions['extensions']
         return any([e for e in exts if e['name'] == extension])
+
+    def get_extension(self, extension_alias):
+        resp, body = self.get('extensions/%s' % extension_alias)
+        body = json.loads(body)
+        return resp, body['extension']
diff --git a/tempest/services/compute/v3/json/extensions_client.py b/tempest/services/compute/v3/json/extensions_client.py
index 60c0217..6e0dc9d 100644
--- a/tempest/services/compute/v3/json/extensions_client.py
+++ b/tempest/services/compute/v3/json/extensions_client.py
@@ -38,3 +38,8 @@
         _, extensions = self.list_extensions()
         exts = extensions['extensions']
         return any([e for e in exts if e['name'] == extension])
+
+    def get_extension(self, extension_alias):
+        resp, body = self.get('extensions/%s' % extension_alias)
+        body = json.loads(body)
+        return resp, body['extension']
diff --git a/tempest/services/compute/v3/xml/extensions_client.py b/tempest/services/compute/v3/xml/extensions_client.py
index e03251c..8f97692 100644
--- a/tempest/services/compute/v3/xml/extensions_client.py
+++ b/tempest/services/compute/v3/xml/extensions_client.py
@@ -43,3 +43,8 @@
         _, extensions = self.list_extensions()
         exts = extensions['extensions']
         return any([e for e in exts if e['name'] == extension])
+
+    def get_extension(self, extension_alias):
+        resp, body = self.get('extensions/%s' % extension_alias, self.headers)
+        body = xml_to_json(etree.fromstring(body))
+        return resp, body
diff --git a/tempest/services/compute/xml/extensions_client.py b/tempest/services/compute/xml/extensions_client.py
index 1395b5a..b17fc4f 100644
--- a/tempest/services/compute/xml/extensions_client.py
+++ b/tempest/services/compute/xml/extensions_client.py
@@ -43,3 +43,8 @@
         _, extensions = self.list_extensions()
         exts = extensions['extensions']
         return any([e for e in exts if e['name'] == extension])
+
+    def get_extension(self, extension_alias):
+        resp, body = self.get('extensions/%s' % extension_alias, self.headers)
+        body = xml_to_json(etree.fromstring(body))
+        return resp, body