gpaddmirrors: add tablespace test

Co-authored-by: NJacob Champion <pchampion@pivotal.io>

gpMgmt/test/behave/mgmt_utils/gpaddmirrors.feature

 @gpaddmirrors
 Feature: Tests for gpaddmirrors
 
+    Scenario: tablespaces work
+        Given the cluster is generated with "3" primaries only
+          And a tablespace is created with data
+         When gpaddmirrors adds 3 mirrors
+          And an FTS probe is triggered
+          And the segments are synchronized
+         Then verify the database has mirrors
+          And the tablespace is valid
+
+         When user kills all primary processes
+          And user can start transactions
+         Then the tablespace is valid
+
 ########################### @concourse_cluster tests ###########################
 # The @concourse_cluster tag denotes the scenario that requires a remote cluster
 

gpMgmt/test/behave/mgmt_utils/steps/mirrors_mgmt_utils.py

@@ -60,6 +60,7 @@ def _write_datadir_config_for_three_mirrors():
     return datadir_config
 
 
+@when("gpaddmirrors adds 3 mirrors")
 def add_three_mirrors(context):
     datadir_config = _write_datadir_config_for_three_mirrors()
     mirror_config_output_file = "/tmp/test_gpaddmirrors.config"