Added testcase to verify error when deleting non existing dump

Changes:
     - Added Verify Error Response For Already Deleted Dump Id

Tested: Successfully ran this from /redfish/managers/test_bmc_dumps.robot

Signed-off-by: manashsarma <manashsarma@in.ibm.com>
Change-Id: I199056113e32299607da68530ac2aaf8e15584d5
diff --git a/redfish/managers/test_bmc_dumps.robot b/redfish/managers/test_bmc_dumps.robot
index 190afba..2abb129 100644
--- a/redfish/managers/test_bmc_dumps.robot
+++ b/redfish/managers/test_bmc_dumps.robot
@@ -22,6 +22,15 @@
 
 *** Test Cases ***
 
+Verify Error Response For Already Deleted Dump Id
+    [Documentation]  Delete non existing BMC dump and expect an error.
+    [Tags]  Verify_Error_Response_For_Already_Deleted_Dump_Id
+
+    ${dump_id}=  Create User Initiated BMC Dump Via Redfish
+    Redfish Delete BMC Dump  ${dump_id}
+    Run Keyword And Expect Error  ValueError: *  Redfish Delete BMC Dump  ${dump_id}
+
+
 Verify User Initiated BMC Dump When Host Powered Off
     [Documentation]  Create user initiated BMC dump at host off state and
     ...  verify dump entry for it.