Merge ~newell-jensen/maas:lp1756181 into maas:master

[Newell Jensen]

LP: #1756181 -- Fixes sync overwritting previous pod tags.

[MAAS Lander (maas-lander)]

UNIT TESTS
-b lp1756181 lp:~newell-jensen/maas/+git/maas into -b master lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: f49374369261730328401741ee68a5bc92a9bcc2

review: Approve

[Blake Rouse (blake-rouse)]

Looks good. Just got one suggestion.

review: Approve

f1b2921... by Newell Jensen on 2018-03-16

Review suggestions.

diff --git a/src/maasserver/models/bmc.py b/src/maasserver/models/bmc.py
index 2ce11ea..737054e 100644
--- a/src/maasserver/models/bmc.py
+++ b/src/maasserver/models/bmc.py
@@ -915,7 +915,7 @@ class Pod(BMC):
         self.local_storage = discovered_pod.local_storage
         self.local_disks = discovered_pod.local_disks
         self.iscsi_storage = discovered_pod.iscsi_storage
-        self.tags = discovered_pod.tags
+        self.tags = list(set(self.tags).union(discovered_pod.tags))
         self.save()
         self.sync_hints(discovered_pod.hints)
         self.sync_machines(discovered_pod.machines, commissioning_user)
diff --git a/src/maasserver/models/tests/test_bmc.py b/src/maasserver/models/tests/test_bmc.py
index fba7c6e..0843067 100644
--- a/src/maasserver/models/tests/test_bmc.py
+++ b/src/maasserver/models/tests/test_bmc.py
@@ -689,7 +689,13 @@ class TestPod(MAASServerTestCase):
 
     def test_sync_pod_properties_and_hints(self):
         discovered = self.make_discovered_pod()
-        pod = factory.make_Pod()
+        discovered.tags = [
+            factory.make_name('tag')
+            for _ in range(3)
+        ]
+        # Create a subset of the discovered pod's tags
+        # to make sure no duplicates are added on sync.
+        pod = factory.make_Pod(tags=[discovered.tags[0]])
         self.patch(pod, 'sync_machines')
         pod.sync(discovered, factory.make_User())
         self.assertThat(
@@ -701,8 +707,11 @@ class TestPod(MAASServerTestCase):
                 local_storage=Equals(discovered.local_storage),
                 local_disks=Equals(discovered.local_disks),
                 iscsi_storage=Equals(discovered.iscsi_storage),
-                tags=Equals(discovered.tags),
                 capabilities=Equals(discovered.capabilities),
+                tags=MatchesSetwise(*[
+                    Equals(tag)
+                    for tag in discovered.tags
+                ]),
                 hints=MatchesStructure(
                     cores=Equals(discovered.hints.cores),
                     cpu_speed=Equals(discovered.hints.cpu_speed),