Added UI tests for Alerta: internal and public addresses

The related fix https://gerrit.mcp.mirantis.com/#/c/34661
adds tests for public endpoints for the rest of
StackLight UI.

Change-Id: Ie94ea242b19e30b7ed7143e01444125182fb6305
diff --git a/test_set/cvp-sanity/fixtures/base.py b/test_set/cvp-sanity/fixtures/base.py
index dccee56..60b8f28 100644
--- a/test_set/cvp-sanity/fixtures/base.py
+++ b/test_set/cvp-sanity/fixtures/base.py
@@ -27,6 +27,17 @@
 
 
 @pytest.fixture(scope='session')
+def check_alerta(local_salt_client):
+    salt_output = local_salt_client.cmd(
+        'prometheus:alerta',
+        'test.ping',
+        expr_form='pillar')
+    if not salt_output:
+        pytest.skip("Alerta service or prometheus:alerta pillar \
+              are not found on this environment.")
+
+
+@pytest.fixture(scope='session')
 def check_kibana(local_salt_client):
     salt_output = local_salt_client.cmd(
         'kibana:server',