diff --git a/core/api/src/test/java/org/onlab/onos/net/DefaultAnnotationsTest.java b/core/api/src/test/java/org/onlab/onos/net/DefaultAnnotationsTest.java
index 274f4b8..9132126 100644
--- a/core/api/src/test/java/org/onlab/onos/net/DefaultAnnotationsTest.java
+++ b/core/api/src/test/java/org/onlab/onos/net/DefaultAnnotationsTest.java
@@ -36,6 +36,23 @@
     }
 
     @Test
+    public void union() {
+        annotations = builder().set("foo", "1").set("bar", "2").remove("buz").build();
+        assertEquals("incorrect keys", of("foo", "bar", "buz"), annotations.keys());
+
+        SparseAnnotations updates = builder().remove("foo").set("bar", "3").set("goo", "4").remove("fuzz").build();
+
+        SparseAnnotations result = DefaultAnnotations.union(annotations, updates);
+
+        assertTrue("remove instruction in original remains", result.isRemoved("buz"));
+        assertTrue("remove instruction in update remains", result.isRemoved("fuzz"));
+        assertEquals("incorrect keys", of("buz", "goo", "bar", "fuzz"), result.keys());
+        assertNull("incorrect value", result.value("foo"));
+        assertEquals("incorrect value", "3", result.value("bar"));
+        assertEquals("incorrect value", "4", result.value("goo"));
+    }
+
+    @Test
     public void merge() {
         annotations = builder().set("foo", "1").set("bar", "2").build();
         assertEquals("incorrect keys", of("foo", "bar"), annotations.keys());
@@ -65,4 +82,4 @@
         DefaultAnnotations.merge(null, null);
     }
 
-}
\ No newline at end of file
+}