diff --git a/apps/yms/ut/src/test/java/org/onosproject/yms/app/yob/YobUnionTest.java b/apps/yms/ut/src/test/java/org/onosproject/yms/app/yob/YobUnionTest.java
new file mode 100644
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+++ b/apps/yms/ut/src/test/java/org/onosproject/yms/app/yob/YobUnionTest.java
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+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yms.app.yob;
+
+import org.junit.Test;
+import org.onosproject.yang.gen.v1.ydt.uniontest.rev20160524.UniontestOpParam;
+import org.onosproject.yang.gen.v1.ydt.uniontest.rev20160524.uniontest.cont1.AugmentedCont1;
+import org.onosproject.yang.gen.v1.ydt.uniontest.rev20160524.uniontest.food.snack.Sportsarena;
+import org.onosproject.yms.app.ydt.YangRequestWorkBench;
+import org.onosproject.yms.app.ydt.YdtExtendedContext;
+import org.onosproject.yms.ydt.YdtContext;
+
+import java.io.IOException;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.onosproject.yms.app.yob.YobTestUtils.ROOT_DATA_RESOURCE;
+
+/**
+ * Test the YANG object building for the YANG data tree based on the union.
+ */
+public class YobUnionTest {
+
+    private YobTestUtils utils = YobTestUtils.instance();
+
+    @Test
+    public void testUnionInLeaf() throws IOException {
+        YangRequestWorkBench ydtBuilder = new YangRequestWorkBench(
+                ROOT_DATA_RESOURCE, null, null, utils.schemaRegistry(), true);
+        ydtBuilder.addChild("uniontest", "ydt.uniontest");
+        ydtBuilder.addChild("unionList", null);
+        ydtBuilder.addLeaf("id", null, "YmluYXJ5");
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        YdtContext rootCtx = ydtBuilder.getRootNode();
+        YdtContext childCtx = rootCtx.getFirstChild();
+        DefaultYobBuilder builder = new DefaultYobBuilder();
+        Object yangObject = builder.getYangObject(
+                (YdtExtendedContext) childCtx, utils.schemaRegistry());
+        assertThat(yangObject, notNullValue());
+        UniontestOpParam unionTestOpParam = ((UniontestOpParam) yangObject);
+
+        byte[] binaryValue = unionTestOpParam.unionList().get(0).id().binary();
+        String value = new String(binaryValue);
+        assertThat(value, is("binary"));
+    }
+
+    @Test
+    public void testUnionInTypedef() throws IOException {
+        YangRequestWorkBench ydtBuilder = new YangRequestWorkBench(
+                ROOT_DATA_RESOURCE, null, null, utils.schemaRegistry(), true);
+        ydtBuilder.addChild("uniontest", "ydt.uniontest");
+        ydtBuilder.addLeaf("name", null, "bit1");
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        YdtContext rootCtx = ydtBuilder.getRootNode();
+        YdtContext childCtx = rootCtx.getFirstChild();
+        DefaultYobBuilder builder = new DefaultYobBuilder();
+        Object yangObject = builder.getYangObject(
+                (YdtExtendedContext) childCtx, utils.schemaRegistry());
+        assertThat(yangObject, notNullValue());
+        UniontestOpParam unionTestOpParam = ((UniontestOpParam) yangObject);
+        assertThat(unionTestOpParam.name().union().bits().get(1), is(true));
+    }
+
+    @Test
+    public void testUnionInGrouping() throws IOException {
+        YangRequestWorkBench ydtBuilder = new YangRequestWorkBench(
+                ROOT_DATA_RESOURCE, null, null, utils.schemaRegistry(), true);
+        ydtBuilder.addChild("uniontest", "ydt.uniontest");
+        ydtBuilder.addChild("cont1", "ydt.uniontest");
+        ydtBuilder.addLeaf("surname", null, "yang");
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        YdtContext rootCtx = ydtBuilder.getRootNode();
+        YdtContext childCtx = rootCtx.getFirstChild();
+        DefaultYobBuilder builder = new DefaultYobBuilder();
+        Object yangObject = builder.getYangObject(
+                (YdtExtendedContext) childCtx, utils.schemaRegistry());
+        assertThat(yangObject, notNullValue());
+        UniontestOpParam uniontestOpParam = ((UniontestOpParam) yangObject);
+        assertThat(uniontestOpParam.cont1().surname().string(), is("yang"));
+    }
+
+    @Test
+    public void testUnionInAugment() throws IOException {
+        YangRequestWorkBench ydtBuilder = new YangRequestWorkBench(
+                ROOT_DATA_RESOURCE, null, null, utils.schemaRegistry(), true);
+        ydtBuilder.addChild("uniontest", "ydt.uniontest");
+        ydtBuilder.addChild("cont1", "ydt.uniontest");
+        ydtBuilder.addLeaf("lastname", null, "bit0");
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        YdtContext rootCtx = ydtBuilder.getRootNode();
+        YdtContext childCtx = rootCtx.getFirstChild();
+        DefaultYobBuilder builder = new DefaultYobBuilder();
+        Object yangObject = builder.getYangObject(
+                (YdtExtendedContext) childCtx, utils.schemaRegistry());
+        assertThat(yangObject, notNullValue());
+        UniontestOpParam uniontestOpParam = ((UniontestOpParam) yangObject);
+
+        AugmentedCont1 augmentedCont1 = (AugmentedCont1) uniontestOpParam
+                .cont1().yangAugmentedInfo(AugmentedCont1.class);
+        assertThat(augmentedCont1.lastname().bits().get(0), is(true));
+    }
+
+    @Test
+    public void testUnionInCase() throws IOException {
+        YangRequestWorkBench ydtBuilder = new YangRequestWorkBench(
+                ROOT_DATA_RESOURCE, null, null, utils.schemaRegistry(), true);
+        ydtBuilder.addChild("uniontest", "ydt.uniontest");
+        ydtBuilder.addChild("food", "ydt.uniontest");
+        ydtBuilder.addLeaf("pretzel", null, "YmluYXJ5");
+        ydtBuilder.traverseToParent();
+        ydtBuilder.traverseToParent();
+        YdtContext rootCtx = ydtBuilder.getRootNode();
+        YdtContext childCtx = rootCtx.getFirstChild();
+        DefaultYobBuilder builder = new DefaultYobBuilder();
+        Object yangObject = builder.getYangObject(
+                (YdtExtendedContext) childCtx, utils.schemaRegistry());
+        assertThat(yangObject, notNullValue());
+        UniontestOpParam uniontestOpParam = ((UniontestOpParam) yangObject);
+        Sportsarena sportsArena = ((Sportsarena) uniontestOpParam.food()
+                .snack());
+        byte[] binaryValue = sportsArena.pretzel().binary();
+        String value = new String(binaryValue);
+        assertThat(value, is("binary"));
+    }
+}