Add tempest test for l3-ha extension

Add missing l3-ha extension under neutron tempest tests.

Change-Id: Ia608d3f5d63a88eefa4e61da6df2f3656c8446a0
Closes-Bug: #1684065
diff --git a/neutron/tests/tempest/api/test_routers.py b/neutron/tests/tempest/api/test_routers.py
index 7a1e458..85bfe82 100644
--- a/neutron/tests/tempest/api/test_routers.py
+++ b/neutron/tests/tempest/api/test_routers.py
@@ -259,6 +259,26 @@
         self.assertNotIn('distributed', show_body['router'])
 
 
+class HaRoutersTest(base_routers.BaseRouterTest):
+
+    @classmethod
+    @test.requires_ext(extension="l3-ha", service="network")
+    def skip_checks(cls):
+        super(HaRoutersTest, cls).skip_checks()
+
+    @decorators.idempotent_id('77db8eae-3aa3-4e61-bf2a-e739ce042e53')
+    def test_convert_legacy_router(self):
+        router = self._create_router(data_utils.rand_name('router'))
+        self.assertNotIn('ha', router)
+        update_body = self.admin_client.update_router(router['id'],
+                                                      ha=True)
+        self.assertTrue(update_body['router']['ha'])
+        show_body = self.admin_client.show_router(router['id'])
+        self.assertTrue(show_body['router']['ha'])
+        show_body = self.client.show_router(router['id'])
+        self.assertNotIn('ha', show_body['router'])
+
+
 class RoutersSearchCriteriaTest(base.BaseSearchCriteriaTest):
 
     resource = 'router'