HONEYCOMB-9: Exception handling for VPP APIs

Change-Id: Ic71a2ac3d01e88cb38596a24a12a7bf8ebf54da5
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

4 files changed, 357 insertions, 48 deletions

diff --git a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VPPConfigDataTreeTest.java b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VPPConfigDataTreeTest.java
index 963df735b..8719a5356 100644
--- a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VPPConfigDataTreeTest.java
+++ b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VPPConfigDataTreeTest.java
@@ -44,8 +44,6 @@ import org.mockito.Mock;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
 import org.opendaylight.mdsal.binding.dom.codec.api.BindingNormalizedNodeSerializer;
 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.Ethernet;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.L2;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.Vxlan;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 import org.opendaylight.yangtools.yang.common.QName;
@@ -58,7 +56,6 @@ import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
-import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
 
 public class VPPConfigDataTreeTest {
 
@@ -89,7 +86,8 @@ public class VPPConfigDataTreeTest {
         doReturn(node).when(snapshot).readNode(path);
 
         final VppDataTreeSnapshot vppDataTreeSnapshot = proxy.takeSnapshot();
-        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future = vppDataTreeSnapshot.read(path);
+        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
+                vppDataTreeSnapshot.read(path);
 
         verify(dataTree).takeSnapshot();
         verify(snapshot).readNode(path);
@@ -132,9 +130,9 @@ public class VPPConfigDataTreeTest {
 
         // Verify all changes were processed:
         verify(vppWriter).update(
-            mapOf(dataBefore, Ethernet.class),
-            mapOf(dataAfter, Ethernet.class),
-            any(WriteContext.class));
+                mapOf(dataBefore, Ethernet.class),
+                mapOf(dataAfter, Ethernet.class),
+                any(WriteContext.class));
 
         // Verify modification was validated
         verify(dataTree).validate(modification);
@@ -142,7 +140,8 @@ public class VPPConfigDataTreeTest {
 
     private Map<InstanceIdentifier<?>, DataObject> mapOf(final DataObject dataBefore, final Class<Ethernet> type) {
         return eq(
-            Collections.<InstanceIdentifier<?>, DataObject>singletonMap(InstanceIdentifier.create(type), dataBefore));
+                Collections.<InstanceIdentifier<?>, DataObject>singletonMap(InstanceIdentifier.create(type),
+                        dataBefore));
     }
 
     private DataObject mockDataObject(final String name, final Class<? extends DataObject> classToMock) {
@@ -154,79 +153,77 @@ public class VPPConfigDataTreeTest {
     @Test
     public void testCommitUndoSuccessful() throws Exception {
         // Prepare data changes:
-        final DataObject dataBefore1 = mockDataObject("before", Ethernet.class);
-        final DataObject dataAfter1 = mockDataObject("after", Ethernet.class);
-
-        final DataObject dataBefore2 = mockDataObject("before", Vxlan.class);
-        final DataObject dataAfter2 = mockDataObject("after", Vxlan.class);
+        final DataObject dataBefore = mockDataObject("before", Ethernet.class);
+        final DataObject dataAfter = mockDataObject("after", Ethernet.class);
 
-        final DataObject dataBefore3 = mockDataObject("before", L2.class);
-        final DataObject dataAfter3 = mockDataObject("after", L2.class);
+        final WriterRegistry.Reverter reverter = mock(WriterRegistry.Reverter.class);
 
-        // reject third applied change
-        final WriterRegistry.Revert revert = mock(WriterRegistry.Revert.class);
-        doThrow(new WriterRegistry.BulkUpdateException(InstanceIdentifier.create(L2.class), new RuntimeException(),
-            revert)).when(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
+        // Fail on update:
+        final VppException failedOnUpdateException = new VppException("update failed");
+        doThrow(new WriterRegistry.BulkUpdateException(InstanceIdentifier.create(Ethernet.class), reverter,
+                failedOnUpdateException)).when(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
 
         // Prepare modification:
         final DataTreeCandidateNode rootNode = mockRootNode();
         // data before:
-        final ContainerNode nodeBefore = mockContainerNode(dataBefore1, dataBefore2, dataBefore3);
+        final ContainerNode nodeBefore = mockContainerNode(dataBefore);
         when(rootNode.getDataBefore()).thenReturn(Optional.<NormalizedNode<?, ?>>fromNullable(nodeBefore));
         // data after:
-        final ContainerNode nodeAfter = mockContainerNode(dataAfter1, dataAfter2, dataAfter3);
+        final ContainerNode nodeAfter = mockContainerNode(dataAfter);
         when(rootNode.getDataAfter()).thenReturn(Optional.<NormalizedNode<?, ?>>fromNullable(nodeAfter));
 
         // Run the test
         try {
             proxy.commit(modification);
-        } catch (DataValidationFailedException | VppException e) {
+        } catch (WriterRegistry.BulkUpdateException e) {
             verify(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
-            verify(revert).revert();
+            verify(reverter).revert();
+            assertEquals(failedOnUpdateException, e.getCause());
             return;
         }
 
-        fail("DataValidationFailedException was expected");
+        fail("WriterRegistry.BulkUpdateException was expected");
     }
 
     @Test
     public void testCommitUndoFailed() throws Exception {
         // Prepare data changes:
-        final DataObject dataBefore1 = mockDataObject("before", Ethernet.class);
-        final DataObject dataAfter1 = mockDataObject("after", Ethernet.class);
+        final DataObject dataBefore = mockDataObject("before", Ethernet.class);
+        final DataObject dataAfter = mockDataObject("after", Ethernet.class);
 
-        final DataObject dataBefore2 = mockDataObject("before", Vxlan.class);
-        final DataObject dataAfter2 = mockDataObject("after", Vxlan.class);
+        final WriterRegistry.Reverter reverter = mock(WriterRegistry.Reverter.class);
 
-        final DataObject dataBefore3 = mockDataObject("before", L2.class);
-        final DataObject dataAfter3 = mockDataObject("after", L2.class);
+        // Fail on update:
+        doThrow(new WriterRegistry.BulkUpdateException(InstanceIdentifier.create(Ethernet.class), reverter,
+                new VppException("update failed"))).when(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
 
-        // reject third applied change
-        final WriterRegistry.Revert revert = mock(WriterRegistry.Revert.class);
-        doThrow(new RuntimeException("revert failed")).when(revert).revert();
-        doThrow(new WriterRegistry.BulkUpdateException(InstanceIdentifier.create(L2.class), new RuntimeException(),
-            revert)).when(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
+        // Fail on revert:
+        final VppException failedOnRevertException = new VppException("update failed");
+        final WriterRegistry.Reverter.RevertFailedException revertFailedException =
+                new WriterRegistry.Reverter.RevertFailedException(Collections.<InstanceIdentifier<?>>emptyList(),
+                        failedOnRevertException);
+        doThrow(revertFailedException).when(reverter).revert();
 
         // Prepare modification:
         final DataTreeCandidateNode rootNode = mockRootNode();
         // data before:
-        final ContainerNode nodeBefore = mockContainerNode(dataBefore1, dataBefore2, dataBefore3);
+        final ContainerNode nodeBefore = mockContainerNode(dataBefore);
         when(rootNode.getDataBefore()).thenReturn(Optional.<NormalizedNode<?, ?>>fromNullable(nodeBefore));
         // data after:
-        final ContainerNode nodeAfter = mockContainerNode(dataAfter1, dataAfter2, dataAfter3);
+        final ContainerNode nodeAfter = mockContainerNode(dataAfter);
         when(rootNode.getDataAfter()).thenReturn(Optional.<NormalizedNode<?, ?>>fromNullable(nodeAfter));
 
         // Run the test
         try {
             proxy.commit(modification);
-        } catch (DataValidationFailedException | VppException e) {
-            // FIXME the behavior with successful and failed revert is the same from outside world
+        } catch (WriterRegistry.Reverter.RevertFailedException e) {
             verify(vppWriter).update(anyMap(), anyMap(), any(WriteContext.class));
-            verify(revert).revert();
+            verify(reverter).revert();
+            assertEquals(failedOnRevertException, e.getCause());
             return;
         }
 
-        fail("DataValidationFailedException was expected");
+        fail("RevertFailedException was expected");
     }
 
     private DataTreeCandidateNode mockRootNode() {
@@ -256,9 +253,9 @@ public class VPPConfigDataTreeTest {
             when(child.getIdentifier()).thenReturn(mock(YangInstanceIdentifier.PathArgument.class));
             list.add(child);
 
-            final Map.Entry entry  = mock(Map.Entry.class);
+            final Map.Entry entry = mock(Map.Entry.class);
             final Class<? extends DataObject> implementedInterface =
-                (Class<? extends DataObject>) modification.getImplementedInterface();
+                    (Class<? extends DataObject>) modification.getImplementedInterface();
             final InstanceIdentifier<?> id = InstanceIdentifier.create(implementedInterface);
 
             doReturn(id).when(entry).getKey();
@@ -267,5 +264,4 @@ public class VPPConfigDataTreeTest {
         }
         return node;
     }
-
 }
diff --git a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VppOperationalDataTreeTest.java b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VppOperationalDataTreeTest.java
index f4b2faa3e..8939f8f52 100644
--- a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VppOperationalDataTreeTest.java
+++ b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/data/VppOperationalDataTreeTest.java
@@ -16,16 +16,22 @@
 
 package io.fd.honeycomb.v3po.impl.data;
 
-import static junit.framework.Assert.assertEquals;
-import static junit.framework.TestCase.assertTrue;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 import static org.mockito.MockitoAnnotations.initMocks;
 
 import com.google.common.base.Optional;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.LinkedListMultimap;
+import com.google.common.collect.Multimap;
 import com.google.common.util.concurrent.CheckedFuture;
 import io.fd.honeycomb.v3po.impl.trans.r.ReaderRegistry;
 import java.util.Map;
@@ -34,10 +40,12 @@ import org.junit.Test;
 import org.mockito.Mock;
 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
 import org.opendaylight.mdsal.binding.dom.codec.api.BindingNormalizedNodeSerializer;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.VppState;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 import org.opendaylight.yangtools.yang.common.QName;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
+import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
 import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
@@ -65,16 +73,16 @@ public class VppOperationalDataTreeTest {
     public void setUp() {
         initMocks(this);
         operationalData = new VppOperationalDataTree(serializer, globalContext, reader);
+        doReturn(schemaNode).when(globalContext).getDataChildByName(any(QName.class));
     }
 
     @Test
-    public void testRead() throws Exception {
+    public void testReadNode() throws Exception {
         final YangInstanceIdentifier yangId = mock(YangInstanceIdentifier.class);
         final YangInstanceIdentifier.PathArgument pArg = mock(YangInstanceIdentifier.PathArgument.class);
         doReturn(pArg).when(yangId).getLastPathArgument();
 
         doReturn(QName.create("namespace", "2012-12-12", "local")).when(pArg).getNodeType();
-        doReturn(schemaNode).when(globalContext).getDataChildByName(any(QName.class));
         doReturn(id).when(serializer).fromYangInstanceIdentifier(yangId);
 
         final DataObject dataObject = mock(DataObject.class);
@@ -91,6 +99,69 @@ public class VppOperationalDataTreeTest {
         final Optional<NormalizedNode<?, ?>> result = future.get();
         assertTrue(result.isPresent());
         assertEquals(expectedValue, result.get());
+    }
+
+    @Test
+    public void testReadNonExistingNode() throws Exception {
+        final YangInstanceIdentifier yangId = mock(YangInstanceIdentifier.class);
+        doReturn(id).when(serializer).fromYangInstanceIdentifier(yangId);
+        doReturn(Optional.absent()).when(reader).read(id);
+
+        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future = operationalData.read(yangId);
+
+        verify(serializer).fromYangInstanceIdentifier(yangId);
+        verify(reader).read(id);
+        final Optional<NormalizedNode<?, ?>> result = future.get();
+        assertFalse(result.isPresent());
+    }
+
+    @Test
+    public void testReadFailed() throws Exception{
+        doThrow(io.fd.honeycomb.v3po.impl.trans.ReadFailedException.class).when(reader).readAll();
+
+        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
+                operationalData.read( YangInstanceIdentifier.EMPTY);
+
+        try {
+            future.checkedGet();
+        } catch (ReadFailedException e) {
+            assertTrue(e.getCause() instanceof io.fd.honeycomb.v3po.impl.trans.ReadFailedException);
+            return;
+        }
+        fail("ReadFailedException was expected");
+    }
+
+    @Test
+    public void testReadRootWithOneNonListElement() throws Exception {
+        // Prepare data
+        final InstanceIdentifier<VppState> vppStateII = InstanceIdentifier.create(VppState.class);
+        final VppState vppState = mock(VppState.class);
+        Multimap<InstanceIdentifier<?>, DataObject> dataObjects = LinkedListMultimap.create();
+        dataObjects.put(vppStateII, vppState);
+        doReturn(dataObjects).when(reader).readAll();
+
+        // Init serializer
+        final YangInstanceIdentifier vppYangId = YangInstanceIdentifier.builder().node(VppState.QNAME).build();
+        when(serializer.toYangInstanceIdentifier(vppStateII)).thenReturn(vppYangId);
+        when(serializer.toNormalizedNode(vppStateII, vppState)).thenReturn(entry);
+        final DataContainerChild<?, ?> vppStateContainer = mock(DataContainerChild.class);
+        doReturn(vppStateContainer).when(entry).getValue();
+        doReturn(vppYangId.getLastPathArgument()).when(vppStateContainer).getIdentifier();
+
+        // Read root
+        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
+                operationalData.read(YangInstanceIdentifier.EMPTY);
+
+        verify(reader).readAll();
+        verify(serializer).toYangInstanceIdentifier(vppStateII);
+        verify(serializer).toNormalizedNode(vppStateII, vppState);
+
+        // Check the result is an ContainerNode with only one child
+        final Optional<NormalizedNode<?, ?>> result = future.get();
+        assertTrue(result.isPresent());
 
+        final ContainerNode rootNode = (ContainerNode) result.get();
+        assertEquals(SchemaContext.NAME, rootNode.getIdentifier().getNodeType());
+        assertEquals(vppStateContainer, Iterables.getOnlyElement(rootNode.getValue()));
     }
 }
\ No newline at end of file
diff --git a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/ReadFailedExceptionTest.java b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/ReadFailedExceptionTest.java
new file mode 100644
index 000000000..b815434a8
--- /dev/null
+++ b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/ReadFailedExceptionTest.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.v3po.impl.trans;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.state.bridge.domains.BridgeDomain;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.state.bridge.domains.bridge.domain.Interface;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class ReadFailedExceptionTest {
+
+    @Test
+    public void testInstantiation() {
+        final InstanceIdentifier<BridgeDomain> id = InstanceIdentifier.create(BridgeDomain.class);
+        ReadFailedException e = new ReadFailedException(id);
+        assertEquals(id, e.getFailedId());
+        assertNull(e.getCause());
+        assertTrue(e.getMessage().contains(id.toString()));
+    }
+
+    @Test
+    public void testInstantiationWithCause() {
+        final InstanceIdentifier<Interface> id = InstanceIdentifier.create(Interface.class);
+        final RuntimeException cause = new RuntimeException();
+        ReadFailedException e = new ReadFailedException(id, cause);
+        assertEquals(id, e.getFailedId());
+        assertEquals(cause, e.getCause());
+        assertTrue(e.getMessage().contains(id.toString()));
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testInstantiationFailed() {
+        new ReadFailedException(null);
+    }
+}
\ No newline at end of file
diff --git a/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/w/util/DelegatingWriterRegistryTest.java b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/w/util/DelegatingWriterRegistryTest.java
new file mode 100644
index 000000000..26f63f40f
--- /dev/null
+++ b/v3po/impl/src/test/java/io/fd/honeycomb/v3po/impl/trans/w/util/DelegatingWriterRegistryTest.java
@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * 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 io.fd.honeycomb.v3po.impl.trans.w.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+
+import io.fd.honeycomb.v3po.impl.trans.VppException;
+import io.fd.honeycomb.v3po.impl.trans.w.VppWriter;
+import io.fd.honeycomb.v3po.impl.trans.w.WriteContext;
+import io.fd.honeycomb.v3po.impl.trans.w.WriterRegistry;
+import io.fd.honeycomb.v3po.impl.trans.w.impl.CompositeRootVppWriter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.Interfaces;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.Vpp;
+import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.VppState;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class DelegatingWriterRegistryTest {
+
+    private final InstanceIdentifier<Vpp> vppId;
+    private final InstanceIdentifier<VppState> vppStateId;
+    private final InstanceIdentifier<Interfaces> interfaceId;
+
+    private WriteContext ctx;
+    private CompositeRootVppWriter<Vpp> vppWriter;
+    private CompositeRootVppWriter<VppState> vppStateWriter;
+    private CompositeRootVppWriter<Interfaces> interfacesWriter;
+
+    private DelegatingWriterRegistry registry;
+
+    public DelegatingWriterRegistryTest() {
+        vppId = InstanceIdentifier.create(Vpp.class);
+        vppStateId = InstanceIdentifier.create(VppState.class);
+        interfaceId = InstanceIdentifier.create(Interfaces.class);
+    }
+
+    @SuppressWarnings("unchecked")
+    private <D extends DataObject> CompositeRootVppWriter<D> mockWriter(Class<D> clazz) {
+        final CompositeRootVppWriter<D> mock = (CompositeRootVppWriter<D>) Mockito.mock(CompositeRootVppWriter.class);
+        doReturn(InstanceIdentifier.create(clazz)).when(mock).getManagedDataObjectType();
+        return mock;
+    }
+
+    private DataObject mockDataObject(final String name, final Class<? extends DataObject> classToMock) {
+        final DataObject dataBefore = mock(classToMock, name);
+        doReturn(classToMock).when(dataBefore).getImplementedInterface();
+        return dataBefore;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Map<InstanceIdentifier<?>, DataObject> asMap(DataObject... objects) {
+        final Map<InstanceIdentifier<?>, DataObject> map = new HashMap<>();
+        for (DataObject object : objects) {
+            final Class<? extends DataObject> implementedInterface =
+                    (Class<? extends DataObject>) object.getImplementedInterface();
+            final InstanceIdentifier<?> id = InstanceIdentifier.create(implementedInterface);
+            map.put(id, object);
+        }
+        return map;
+    }
+
+    @Before
+    public void setUp() {
+        ctx = mock(WriteContext.class);
+        vppWriter = mockWriter(Vpp.class);
+        vppStateWriter = mockWriter(VppState.class);
+        interfacesWriter = mockWriter(Interfaces.class);
+
+        final List<VppWriter<? extends DataObject>> writers = new ArrayList<>();
+        writers.add(vppWriter);
+        writers.add(vppStateWriter);
+        writers.add(interfacesWriter);
+
+        registry = new DelegatingWriterRegistry(writers);
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void testGetManagedDataObjectType() {
+        registry.getManagedDataObjectType();
+    }
+
+    @Test
+    public void testBulkUpdateRevert() throws Exception {
+        // Prepare data changes:
+        final DataObject dataBefore1 = mockDataObject("Vpp before", Vpp.class);
+        final DataObject dataAfter1 = mockDataObject("Vpp after", Vpp.class);
+
+        final DataObject dataBefore2 = mockDataObject("VppState before", VppState.class);
+        final DataObject dataAfter2 = mockDataObject("VppState after", VppState.class);
+
+        // Fail on update
+        doThrow(new VppException("vpp failed")).when(vppStateWriter)
+                .update(vppStateId, dataBefore2, dataAfter2, ctx);
+
+        // Run the test
+        try {
+            registry.update(asMap(dataBefore1, dataBefore2), asMap(dataAfter1, dataAfter2), ctx);
+        } catch (WriterRegistry.BulkUpdateException e) {
+            // Check second update failed
+            assertEquals(vppStateId, e.getFailedId());
+            verify(vppWriter).update(vppId, dataBefore1, dataAfter1, ctx);
+            verify(vppStateWriter).update(vppStateId, dataBefore2, dataAfter2, ctx);
+
+            // Try to revert changes
+            e.revertChanges();
+
+            // Check revert was successful
+            verify(vppWriter).update(vppId, dataAfter1, dataBefore1, ctx);
+            verify(vppStateWriter, never()).update(vppStateId, dataAfter2, dataBefore2, ctx);
+
+            return;
+        }
+        fail("BulkUpdateException expected");
+    }
+
+    @Test
+    public void testBulkUpdateRevertFail() throws Exception {
+        // Prepare data changes:
+        final DataObject dataBefore1 = mockDataObject("Vpp before", Vpp.class);
+        final DataObject dataAfter1 = mockDataObject("Vpp after", Vpp.class);
+
+        final DataObject dataBefore2 = mockDataObject("VppState before", VppState.class);
+        final DataObject dataAfter2 = mockDataObject("VppState after", VppState.class);
+
+        final DataObject dataBefore3 = mockDataObject("Interfaces before", Interfaces.class);
+        final DataObject dataAfter3 = mockDataObject("Interfaces after", Interfaces.class);
+
+        // Fail on the third update
+        doThrow(new VppException("vpp failed")).when(interfacesWriter)
+                .update(interfaceId, dataBefore3, dataAfter3, ctx);
+
+        // Fail on the second revert
+        doThrow(new VppException("vpp failed again")).when(vppWriter)
+                .update(vppId, dataAfter1, dataBefore1, ctx);
+
+        // Run the test
+        try {
+            registry.update(asMap(dataBefore1, dataBefore2, dataBefore3), asMap(dataAfter1, dataAfter2, dataAfter3), ctx);
+        } catch (WriterRegistry.BulkUpdateException e) {
+            // Check third update failed
+            assertEquals(interfaceId, e.getFailedId());
+            verify(vppWriter).update(vppId, dataBefore1, dataAfter1, ctx);
+            verify(vppStateWriter).update(vppStateId, dataBefore2, dataAfter2, ctx);
+            verify(interfacesWriter).update(interfaceId, dataBefore3, dataAfter3, ctx);
+
+            // Try to revert changes
+            try {
+                e.revertChanges();
+            } catch (WriterRegistry.Reverter.RevertFailedException e2) {
+                // Check second revert failed
+                assertEquals(Collections.singletonList(vppId), e2.getNotRevertedChanges());
+                verify(vppWriter).update(vppId, dataAfter1, dataBefore1, ctx);
+                verify(vppStateWriter).update(vppStateId, dataAfter2, dataBefore2, ctx);
+                verify(interfacesWriter, never()).update(interfaceId, dataAfter3, dataBefore3, ctx);
+                return;
+            }
+            fail("WriterRegistry.Revert.RevertFailedException expected");
+        }
+        fail("BulkUpdateException expected");
+    }
+}
\ No newline at end of file