Reproducer test for live migration with power management

Building on the previous patch's refactor, we can now do functional
testing of live migration with CPU power management. We quickly notice
that it's mostly broken, leaving the CPUs powered up on the source,
and not powering them up on the dest.

Related-bug: 2056613
Change-Id: Ib4de77d68ceeffbc751bca3567ada72228b750af

nova/tests/functional/libvirt/test_power_manage.py

@@ -88,6 +88,86 @@ class PowerManagementTestsBase(base.ServersTestBase):
                 self.assertEqual('performance', core.governor)
 
 
+class FakeCore(object):
+
+    def __init__(self, i):
+        self.ident = i
+        self.power_state = 'online'
+
+    @property
+    def online(self):
+        return self.power_state == 'online'
+
+    @online.setter
+    def online(self, state):
+        if state:
+            self.power_state = 'online'
+        else:
+            self.power_state = 'offline'
+
+
+class CoresStub(object):
+
+    def __init__(self):
+        self.cores = {}
+
+    def __call__(self, i):
+        if i not in self.cores:
+            self.cores[i] = FakeCore(i)
+        return self.cores[i]
+
+
+class PowerManagementLiveMigrationTests(base.LibvirtMigrationMixin,
+                                        PowerManagementTestsBase):
+
+    def setUp(self):
+        super().setUp()
+
+        self.useFixture(nova_fixtures.SysFileSystemFixture())
+        self.flags(cpu_dedicated_set='1-9', cpu_shared_set=None,
+                   group='compute')
+        self.flags(vcpu_pin_set=None)
+        self.flags(cpu_power_management=True, group='libvirt')
+
+        # NOTE(artom) Fill up all dedicated CPUs. This makes the assertions
+        # further down easier.
+        self.pcpu_flavor_id = self._create_flavor(
+            vcpu=9, extra_spec=self.extra_spec)
+
+        self.start_compute(
+            host_info=fakelibvirt.HostInfo(cpu_nodes=1, cpu_sockets=1,
+                                           cpu_cores=5, cpu_threads=2),
+            hostname='src')
+        self.src = self.computes['src']
+        self.src.driver.cpu_api.core = CoresStub()
+        # NOTE(artom) In init_host() the libvirt driver calls
+        # power_down_all_dedicated_cpus(). Call it again now after swapping to
+        # our stub to fake reality.
+        self.src.driver.cpu_api.power_down_all_dedicated_cpus()
+
+        self.start_compute(
+            host_info=fakelibvirt.HostInfo(cpu_nodes=1, cpu_sockets=1,
+                                           cpu_cores=5, cpu_threads=2),
+            hostname='dest')
+        self.dest = self.computes['dest']
+        self.dest.driver.cpu_api.power_down_all_dedicated_cpus()
+
+    def assert_cores(self, host, cores, online=True):
+        for i in cores:
+            self.assertEqual(online, host.driver.cpu_api.core(i).online)
+
+    def test_live_migrate_server(self):
+        self.server = self._create_server(
+            flavor_id=self.pcpu_flavor_id,
+            expected_state='ACTIVE', host='src')
+        server = self._live_migrate(self.server)
+        self.assertEqual('dest', server['OS-EXT-SRV-ATTR:host'])
+        # FIXME(artom) We've not powered up the dest cores, and left the src
+        # cores powered on.
+        self.assert_cores(self.src, range(1, 10), online=True)
+        self.assert_cores(self.dest, range(1, 10), online=False)
+
+
 class PowerManagementTests(PowerManagementTestsBase):
     """Test suite for a single host with 9 dedicated cores and 1 used for OS"""