Refactor a few things inside the xenapi unit tests.

There were a couple of places where basically the same code was being
used to create a simulated VDI record -- these have been brought together
into _make_fake_vdi.

fake_fetch_image was stubbing out parse_xmlrpc_value, which looks like it
was a workaround for the fact that the task result wasn't being populated
properly.  I've fixed the latter, and removed the former.  This moved the
JSON handling into xenapi.fake.

There were a couple of implementations of host_call_plugin, which contained
a lot of duplicated code.  In particular, they both made a simulated VDI
record, even when the plugin function being called didn't require that.
I have brought the two implementations together into fake.SessionBase, with
overrides in the subclasses for those things that are specific to a given
test.  I have also made the baseclass strict about flagging unsimulated
plugin calls, and added explicit handling for agent.version, and a couple
of methods from glance and migration.

Change-Id: Idc3a872870ae15165747a04ecd1b48e889bd90fd

2 files changed, 55 insertions, 40 deletions

diff --git a/nova/tests/xenapi/stubs.py b/nova/tests/xenapi/stubs.py
index 51ca78708..7c5634c5a 100644
--- a/nova/tests/xenapi/stubs.py
+++ b/nova/tests/xenapi/stubs.py
@@ -17,7 +17,6 @@
 """Stubouts, mocks and fixtures for the test suite"""
 
 import eventlet
-import json
 import random
 
 from nova.virt import xenapi_conn
@@ -32,23 +31,10 @@ def stubout_instance_snapshot(stubs):
     @classmethod
     def fake_fetch_image(cls, context, session, instance, image, user,
                          project, type):
-        from nova.virt.xenapi.fake import create_vdi
-        name_label = "instance-%s" % instance.id
-        #TODO: create fake SR record
-        sr_ref = "fakesr"
-        vdi_ref = create_vdi(name_label=name_label, read_only=False,
-                             sr_ref=sr_ref, sharable=False)
-        vdi_rec = session.call_xenapi("VDI.get_record", vdi_ref)
-        vdi_uuid = vdi_rec['uuid']
-        return [dict(vdi_type='os', vdi_uuid=vdi_uuid)]
+        return [dict(vdi_type='os', vdi_uuid=_make_fake_vdi())]
 
     stubs.Set(vm_utils.VMHelper, 'fetch_image', fake_fetch_image)
 
-    def fake_parse_xmlrpc_value(val):
-        return val
-
-    stubs.Set(xenapi_conn, '_parse_xmlrpc_value', fake_parse_xmlrpc_value)
-
     def fake_wait_for_vhd_coalesce(session, instance_id, sr_ref, vdi_ref,
                               original_parent_uuid):
         #TODO(sirp): Should we actually fake out the data here
@@ -156,38 +142,35 @@ def stubout_loopingcall_delay(stubs):
     stubs.Set(utils.LoopingCall, 'start', fake_start)
 
 
+def _make_fake_vdi():
+    sr_ref = fake.get_all('SR')[0]
+    vdi_ref = fake.create_vdi('', False, sr_ref, False)
+    vdi_rec = fake.get_record('VDI', vdi_ref)
+    return vdi_rec['uuid']
+
+
 class FakeSessionForVMTests(fake.SessionBase):
     """ Stubs out a XenAPISession for VM tests """
     def __init__(self, uri):
         super(FakeSessionForVMTests, self).__init__(uri)
 
     def host_call_plugin(self, _1, _2, plugin, method, _5):
-        # If the call is for 'copy_kernel_vdi' return None.
-        if method == 'copy_kernel_vdi':
-            return
-        sr_ref = fake.get_all('SR')[0]
-        vdi_ref = fake.create_vdi('', False, sr_ref, False)
-        vdi_rec = fake.get_record('VDI', vdi_ref)
-        if plugin == "glance" and method == "download_vhd":
-            ret_str = json.dumps([dict(vdi_type='os',
-                    vdi_uuid=vdi_rec['uuid'])])
+        if (plugin, method) == ('glance', 'download_vhd'):
+            return fake.as_json(dict(vdi_type='os',
+                                     vdi_uuid=_make_fake_vdi()))
         else:
-            ret_str = vdi_rec['uuid']
-        return '<string>%s</string>' % ret_str
+            return (super(FakeSessionForVMTests, self).
+                    host_call_plugin(_1, _2, plugin, method, _5))
 
     def host_call_plugin_swap(self, _1, _2, plugin, method, _5):
-        sr_ref = fake.get_all('SR')[0]
-        vdi_ref = fake.create_vdi('', False, sr_ref, False)
-        vdi_rec = fake.get_record('VDI', vdi_ref)
-        if plugin == "glance" and method == "download_vhd":
-            swap_vdi_ref = fake.create_vdi('', False, sr_ref, False)
-            swap_vdi_rec = fake.get_record('VDI', swap_vdi_ref)
-            ret_str = json.dumps(
-                    [dict(vdi_type='os', vdi_uuid=vdi_rec['uuid']),
-                    dict(vdi_type='swap', vdi_uuid=swap_vdi_rec['uuid'])])
+        if (plugin, method) == ('glance', 'download_vhd'):
+            return fake.as_json(dict(vdi_type='os',
+                                     vdi_uuid=_make_fake_vdi()),
+                                dict(vdi_type='swap',
+                                     vdi_uuid=_make_fake_vdi()))
         else:
-            ret_str = vdi_rec['uuid']
-        return '<string>%s</string>' % ret_str
+            return (super(FakeSessionForVMTests, self).
+                    host_call_plugin(_1, _2, plugin, method, _5))
 
     def VM_start(self, _1, ref, _2, _3):
         vm = fake.get_record('VM', ref)
diff --git a/nova/virt/xenapi/fake.py b/nova/virt/xenapi/fake.py
index 59ea19fd0..4f40bb656 100644
--- a/nova/virt/xenapi/fake.py
+++ b/nova/virt/xenapi/fake.py
@@ -51,8 +51,10 @@ A fake XenAPI SDK.
 """
 
 
+import json
 import random
 import uuid
+from xml.sax.saxutils import escape
 
 from pprint import pformat
 
@@ -316,6 +318,21 @@ def check_for_session_leaks():
                               _db_content['session'])
 
 
+def as_value(s):
+    """Helper function for simulating XenAPI plugin responses.  It
+    escapes and wraps the given argument."""
+    return '<value>%s</value>' % escape(s)
+
+
+def as_json(*args, **kwargs):
+    """Helper function for simulating XenAPI plugin responses for those
+    that are returning JSON.  If this function is given plain arguments,
+    then these are rendered as a JSON list.  If it's given keyword
+    arguments then these are rendered as a JSON dict."""
+    arg = args or kwargs
+    return json.dumps(arg)
+
+
 class Failure(Exception):
     def __init__(self, details):
         self.details = details
@@ -435,8 +452,20 @@ class SessionBase(object):
         #Always return 12GB available
         return 12 * 1024 * 1024 * 1024
 
-    def host_call_plugin(self, *args):
-        return 'herp'
+    def host_call_plugin(self, _1, _2, plugin, method, _5):
+        if (plugin, method) == ('agent', 'version'):
+            return as_json(returncode='0', message='1.0')
+        elif (plugin, method) == ('glance', 'copy_kernel_vdi'):
+            return ''
+        elif (plugin, method) == ('glance', 'upload_vhd'):
+            return ''
+        elif (plugin, method) == ('migration', 'move_vhds_into_sr'):
+            return ''
+        elif (plugin, method) == ('migration', 'transfer_vhd'):
+            return ''
+        else:
+            raise Exception('No simulation in host_call_plugin for %s,%s' %
+                            (plugin, method))
 
     def VDI_resize_online(self, *args):
         return 'derp'
@@ -624,7 +653,10 @@ class SessionBase(object):
         task = _db_content['task'][task_ref]
         func = name[len('Async.'):]
         try:
-            task['result'] = self.xenapi_request(func, params[1:])
+            result = self.xenapi_request(func, params[1:])
+            if result:
+                result = as_value(result)
+            task['result'] = result
             task['status'] = 'success'
         except Failure, exc:
             task['error_info'] = exc.details