Added test to check minions status

The CVP Sanity tests skip the nodes automatically if this minion
does not respond in 1 sec (salt_timeout in config) time.
Sometimes all the tests can pass, but some KVM nodes along with its
Control plane VMs can be down and CVP tests will not test this and
will not inform about this.
The tests check that all minions are up.

Change-Id: Ib8495aeb043448b36aea85bb31ee2650d655075e
diff --git a/test_set/cvp-sanity/tests/test_nodes.py b/test_set/cvp-sanity/tests/test_nodes.py
new file mode 100644
index 0000000..5f8b2dc
--- /dev/null
+++ b/test_set/cvp-sanity/tests/test_nodes.py
@@ -0,0 +1,19 @@
+import json
+import pytest
+
+
+def test_minions_status(local_salt_client):
+    result = local_salt_client.cmd(
+        'salt:master',
+        'cmd.run',
+        ['salt-run manage.status timeout=10 --out=json'],
+        expr_form='pillar')
+    statuses = {}
+    try:
+        statuses = json.loads(result.values()[0])
+    except Exception as e:
+        pytest.fail(
+            "Could not check the result: {}\n"
+            "Nodes status result: {}".format(e, result))
+    assert not statuses["down"], "Some minions are down:\n {}".format(
+        statuses["down"])