[ONOS-7493] Segment routing may uninstall forwarding with no next id

Change-Id: Id78b9ed94633b7e96fdeebe185e28d6de386e3ec
diff --git a/pipelines/fabric/src/test/java/org/onosproject/pipelines/fabric/FabricInterpreterTest.java b/pipelines/fabric/src/test/java/org/onosproject/pipelines/fabric/FabricInterpreterTest.java
index f0d27f35..8d97f20 100644
--- a/pipelines/fabric/src/test/java/org/onosproject/pipelines/fabric/FabricInterpreterTest.java
+++ b/pipelines/fabric/src/test/java/org/onosproject/pipelines/fabric/FabricInterpreterTest.java
@@ -30,6 +30,7 @@
 import org.onosproject.net.pi.runtime.PiActionParam;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 
 /**
  * Test for fabric interpreter.
@@ -125,6 +126,17 @@
         assertEquals(expectedAction, mappedAction);
     }
 
+    /**
+     * Map empty treatment for forwarding block to nop action.
+     */
+    @Test
+    public void testEmptyForwardingTreatment() throws Exception {
+        TrafficTreatment treatment = DefaultTrafficTreatment.emptyTreatment();
+        PiAction mappedAction = interpreter.mapTreatment(treatment,
+                                                         FabricConstants.TBL_UNICAST_V4_ID);
+        assertNull(mappedAction);
+    }
+
     /* Next control block */
 
     /**