Added Test Cases for disable enable ONUs VOL-2732

Change-Id: I07def03019819ec52ccbf560acc41404219ceeb8
diff --git a/libraries/voltctl.robot b/libraries/voltctl.robot
index d48d693..95b0874 100644
--- a/libraries/voltctl.robot
+++ b/libraries/voltctl.robot
@@ -183,6 +183,15 @@
         ...    onu_reason=omci-flows-pushed    onu=True
     END
 
+Validate ONU Devices DisableEnable
+    [Arguments]    ${admin_state}    ${oper_status}    ${connect_status}    ${List_ONU_Serial}
+    [Documentation]    Parses the output of "voltctl device list" and inspects device    ${List_ONU_Serial}
+    ...    Iteratively match on each Serial number contained in ${List_ONU_Serial} and inspects ONU states
+    FOR    ${serial_number}    IN    @{List_ONU_Serial}
+        Validate Device    ${admin_state}    ${oper_status}    ${connect_status}    ${serial_number}
+        ...    onu_reason=omci-flows-pushed    onu=False
+    END
+
 Validate Device Port Types
     [Documentation]
     ...    Parses the output of voltctl device port list <device_id> and matches the port types listed
diff --git a/tests/functional/Voltha_ScaleFunctionalTests.robot b/tests/functional/Voltha_ScaleFunctionalTests.robot
index 44ae691..39c2aa7 100644
--- a/tests/functional/Voltha_ScaleFunctionalTests.robot
+++ b/tests/functional/Voltha_ScaleFunctionalTests.robot
@@ -157,6 +157,26 @@
     #Validate ONU peer ids
     Validate ONU Peer Id    ${olt_device_id}    ${List_ONU_Serial}
 
+Test Disable and Enable ONU
+    [Documentation]     Perform disable/enable on the ONUs and validate test assertions
+    [Tags]      active  VOL-2732
+    FOR    ${I}    IN RANGE    0    ${num_onus}
+        ${src}=    Set Variable    ${hosts.src[${I}]}
+        ${dst}=    Set Variable    ${hosts.dst[${I}]}
+        ${onu_device_id}=    Get Device ID From SN    ${src['onu']}
+        Disable Device    ${onu_device_id}
+    END
+    Wait Until Keyword Succeeds ${long_timeout}  20s    Validate ONU Devices DisableEnable
+    ... DISABLED        UNKNOWN REACHABLE       ${List_ONU_Serial}
+    FOR    ${I}    IN RANGE    0    ${num_onus}
+        ${src}=    Set Variable    ${hosts.src[${I}]}
+        ${dst}=    Set Variable    ${hosts.dst[${I}]}
+        ${onu_device_id}=    Get Device ID From SN    ${src['onu']}
+        Enable Device    ${onu_device_id}
+    END
+    Wait Until Keyword Succeeds ${long_timeout} 20s     Validate ONU Devices DisableEnable
+    ... ENABLED ACTIVE  REACHABLE       ${List_ONU_Serial}
+
 *** Keywords ***
 Setup Suite
     [Documentation]    Set up the test suite