HONEYCOMB-94 Reimplement writer registry with better ordering options

Now the registry is flat and allows for full control of writer execution order

Change-Id: I864e1d676588ffe59b596145e0829e81b1a1ed2f
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

4 files changed, 547 insertions, 189 deletions

diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/impl/write/util/DelegatingWriterRegistryTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/impl/write/util/DelegatingWriterRegistryTest.java
deleted file mode 100644
index f51e49db5..000000000
--- a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/impl/write/util/DelegatingWriterRegistryTest.java
+++ /dev/null
@@ -1,189 +0,0 @@
-/*
- * 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.translate.impl.write.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.translate.util.write.DelegatingWriterRegistry;
-import io.fd.honeycomb.v3po.translate.write.WriteContext;
-import io.fd.honeycomb.v3po.translate.write.WriteFailedException;
-import io.fd.honeycomb.v3po.translate.write.Writer;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
-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 Writer<Vpp> writer;
-    private Writer<VppState> vppStateWriter;
-    private Writer<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> Writer<D> mockWriter(Class<D> clazz) {
-        final Writer<D> mock = (Writer<D>) Mockito.mock(Writer.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);
-        writer = mockWriter(Vpp.class);
-        vppStateWriter = mockWriter(VppState.class);
-        interfacesWriter = mockWriter(Interfaces.class);
-
-        final List<Writer<? extends DataObject>> writers = new ArrayList<>();
-        writers.add(writer);
-        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
-        Mockito.doThrow(new WriteFailedException(InstanceIdentifier.create(Vpp.class), "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(writer).update(vppId, dataBefore1, dataAfter1, ctx);
-            verify(vppStateWriter).update(vppStateId, dataBefore2, dataAfter2, ctx);
-
-            // Try to revert changes
-            e.revertChanges();
-
-            // Check revert was successful
-            verify(writer).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 WriteFailedException(InstanceIdentifier.create(Vpp.class), "vpp failed")).when(interfacesWriter)
-                .update(interfaceId, dataBefore3, dataAfter3, ctx);
-
-        // Fail on the second revert
-        doThrow(new WriteFailedException(InstanceIdentifier.create(Vpp.class), "vpp failed")).when(writer)
-                .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(writer).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(writer).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
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java
new file mode 100644
index 000000000..ec407b685
--- /dev/null
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java
@@ -0,0 +1,156 @@
+package io.fd.honeycomb.v3po.translate.util.write.registry;
+
+import static org.hamcrest.CoreMatchers.anyOf;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.v3po.translate.write.Writer;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Test;
+import org.opendaylight.yangtools.yang.binding.ChildOf;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class FlatWriterRegistryBuilderTest {
+
+
+    @Test
+    public void testRelationsBefore() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        /*
+            1   ->  2   ->  3
+                        ->  4
+         */
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject3.class));
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject4.class));
+        flatWriterRegistryBuilder.addWriterBefore(mockWriter(DataObject2.class),
+                Lists.newArrayList(DataObject3.IID, DataObject4.IID));
+        flatWriterRegistryBuilder.addWriterBefore(mockWriter(DataObject1.class), DataObject2.IID);
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedWriters();
+
+        final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+        assertEquals(DataObject1.IID, typesInList.get(0));
+        assertEquals(DataObject2.IID, typesInList.get(1));
+        assertThat(typesInList.get(2), anyOf(equalTo(DataObject3.IID), equalTo(DataObject4.IID)));
+        assertThat(typesInList.get(3), anyOf(equalTo(DataObject3.IID), equalTo(DataObject4.IID)));
+    }
+
+    @Test
+    public void testRelationsAfter() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        /*
+            1   ->  2   ->  3
+                        ->  4
+         */
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject2.class), DataObject1.IID);
+        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject3.class), DataObject2.IID);
+        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject4.class), DataObject2.IID);
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedWriters();
+
+        final List<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+        assertEquals(DataObject1.IID, typesInList.get(0));
+        assertEquals(DataObject2.IID, typesInList.get(1));
+        assertThat(typesInList.get(2), anyOf(equalTo(DataObject3.IID), equalTo(DataObject4.IID)));
+        assertThat(typesInList.get(3), anyOf(equalTo(DataObject3.IID), equalTo(DataObject4.IID)));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testRelationsLoop() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        /*
+            1   ->  2   ->  1
+         */
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject2.class), DataObject1.IID);
+        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject1.class), DataObject2.IID);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testAddWriterTwice() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
+    }
+
+    @Test
+    public void testAddSubtreeWriter() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        flatWriterRegistryBuilder.addSubtreeWriter(
+                Sets.newHashSet(DataObject4.DataObject5.IID,
+                                DataObject4.DataObject5.IID),
+                mockWriter(DataObject4.class));
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedWriters();
+        final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+
+        assertEquals(DataObject4.IID, typesInList.get(0));
+        assertEquals(1, typesInList.size());
+    }
+
+    @Test
+    public void testCreateSubtreeWriter() throws Exception {
+        final Writer<?> forWriter = SubtreeWriter.createForWriter(Sets.newHashSet(
+                DataObject4.DataObject5.IID,
+                DataObject4.DataObject5.DataObject51.IID,
+                DataObject4.DataObject6.IID),
+                mockWriter(DataObject4.class));
+        assertThat(forWriter, instanceOf(SubtreeWriter.class));
+        assertThat(((SubtreeWriter<?>) forWriter).getHandledChildTypes().size(), is(3));
+        assertThat(((SubtreeWriter<?>) forWriter).getHandledChildTypes(), hasItems(DataObject4.DataObject5.IID,
+                DataObject4.DataObject6.IID, DataObject4.DataObject5.DataObject51.IID));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testCreateInvalidSubtreeWriter() throws Exception {
+        SubtreeWriter.createForWriter(Sets.newHashSet(
+                InstanceIdentifier.create(DataObject3.class).child(DataObject3.DataObject31.class)),
+                mockWriter(DataObject4.class));
+    }
+
+    @SuppressWarnings("unchecked")
+    private Writer<? extends DataObject> mockWriter(final Class<? extends DataObject> doClass)
+            throws NoSuchFieldException, IllegalAccessException {
+        final Writer mock = mock(Writer.class);
+        when(mock.getManagedDataObjectType()).thenReturn((InstanceIdentifier<?>) doClass.getDeclaredField("IID").get(null));
+        return mock;
+    }
+
+    private abstract static class DataObject1 implements DataObject {
+        static InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
+    }
+    private abstract static class DataObject2 implements DataObject {
+        static InstanceIdentifier<DataObject2> IID = InstanceIdentifier.create(DataObject2.class);
+    }
+    private abstract static class DataObject3 implements DataObject {
+        static InstanceIdentifier<DataObject3> IID = InstanceIdentifier.create(DataObject3.class);
+        private abstract static class DataObject31 implements DataObject, ChildOf<DataObject3> {
+            static InstanceIdentifier<DataObject31> IID = DataObject3.IID.child(DataObject31.class);
+        }
+    }
+    private abstract static class DataObject4 implements DataObject {
+        static InstanceIdentifier<DataObject4> IID = InstanceIdentifier.create(DataObject4.class);
+        private abstract static class DataObject5 implements DataObject, ChildOf<DataObject4> {
+            static InstanceIdentifier<DataObject5> IID = DataObject4.IID.child(DataObject5.class);
+            private abstract static class DataObject51 implements DataObject, ChildOf<DataObject5> {
+                static InstanceIdentifier<DataObject51> IID = DataObject5.IID.child(DataObject51.class);
+            }
+        }
+        private abstract static class DataObject6 implements DataObject, ChildOf<DataObject4> {
+            static InstanceIdentifier<DataObject6> IID = DataObject4.IID.child(DataObject6.class);
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java
new file mode 100644
index 000000000..7fb5779f3
--- /dev/null
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java
@@ -0,0 +1,295 @@
+package io.fd.honeycomb.v3po.translate.util.write.registry;
+
+import static org.hamcrest.CoreMatchers.hasItem;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.Multimap;
+import io.fd.honeycomb.v3po.translate.write.DataObjectUpdate;
+import io.fd.honeycomb.v3po.translate.write.WriteContext;
+import io.fd.honeycomb.v3po.translate.write.Writer;
+import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.InOrder;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class FlatWriterRegistryTest {
+
+    @Mock
+    private Writer<DataObject1> writer1;
+    @Mock
+    private Writer<DataObject2> writer2;
+    @Mock
+    private Writer<DataObject3> writer3;
+    @Mock
+    private WriteContext ctx;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        when(writer1.getManagedDataObjectType()).thenReturn(DataObject1.IID);
+        when(writer2.getManagedDataObjectType()).thenReturn(DataObject2.IID);
+        when(writer3.getManagedDataObjectType()).thenReturn(DataObject3.IID);
+    }
+
+    @Test
+    public void testSingleUpdate() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1));
+
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 before = mock(DataObject1.class);
+        final DataObject1 after = mock(DataObject1.class);
+        flatWriterRegistry.update(iid, before, after, ctx);
+
+        verify(writer1).update(iid, before, after, ctx);
+    }
+
+    @Test
+    public void testMultipleUpdatesForSingleWriter() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final InstanceIdentifier<DataObject1> iid2 = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 dataObject = mock(DataObject1.class);
+        updates.put(DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        updates.put(DataObject1.IID, DataObjectUpdate.create(iid2, dataObject, dataObject));
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+
+        verify(writer1).update(iid, dataObject, dataObject, ctx);
+        verify(writer1).update(iid2, dataObject, dataObject, ctx);
+        // Invoked when registry is being created
+        verifyNoMoreInteractions(writer1);
+        verifyZeroInteractions(writer2);
+    }
+
+    @Test
+    public void testMultipleUpdatesForMultipleWriters() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 dataObject = mock(DataObject1.class);
+        updates.put(DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        final InstanceIdentifier<DataObject2> iid2 = InstanceIdentifier.create(DataObject2.class);
+        final DataObject2 dataObject2 = mock(DataObject2.class);
+        updates.put(DataObject2.IID, DataObjectUpdate.create(iid2, dataObject2, dataObject2));
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+
+        final InOrder inOrder = inOrder(writer1, writer2);
+        inOrder.verify(writer1).update(iid, dataObject, dataObject, ctx);
+        inOrder.verify(writer2).update(iid2, dataObject2, dataObject2, ctx);
+
+        verifyNoMoreInteractions(writer1);
+        verifyNoMoreInteractions(writer2);
+    }
+
+    @Test
+    public void testMultipleDeletesForMultipleWriters() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate.DataObjectDelete> deletes = HashMultimap.create();
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 dataObject = mock(DataObject1.class);
+        deletes.put(DataObject1.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid, dataObject, null)));
+        final InstanceIdentifier<DataObject2> iid2 = InstanceIdentifier.create(DataObject2.class);
+        final DataObject2 dataObject2 = mock(DataObject2.class);
+        deletes.put(DataObject2.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid2, dataObject2, null)));
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(ImmutableMultimap.of(), deletes), ctx);
+
+        final InOrder inOrder = inOrder(writer1, writer2);
+        // Reversed order of invocation, first writer2 and then writer1
+        inOrder.verify(writer2).update(iid2, dataObject2, null, ctx);
+        inOrder.verify(writer1).update(iid, dataObject, null, ctx);
+
+        verifyNoMoreInteractions(writer1);
+        verifyNoMoreInteractions(writer2);
+    }
+
+    @Test
+    public void testMultipleUpdatesAndDeletesForMultipleWriters() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate.DataObjectDelete> deletes = HashMultimap.create();
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 dataObject = mock(DataObject1.class);
+        // Writer 1 delete
+        deletes.put(DataObject1.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid, dataObject, null)));
+        // Writer 1 update
+        updates.put(DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        final InstanceIdentifier<DataObject2> iid2 = InstanceIdentifier.create(DataObject2.class);
+        final DataObject2 dataObject2 = mock(DataObject2.class);
+        // Writer 2 delete
+        deletes.put(DataObject2.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid2, dataObject2, null)));
+        // Writer 2 update
+        updates.put(DataObject2.IID, DataObjectUpdate.create(iid2, dataObject2, dataObject2));
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, deletes), ctx);
+
+        final InOrder inOrder = inOrder(writer1, writer2);
+        // Reversed order of invocation, first writer2 and then writer1 for deletes
+        inOrder.verify(writer2).update(iid2, dataObject2, null, ctx);
+        inOrder.verify(writer1).update(iid, dataObject, null, ctx);
+        // Then also updates are processed
+        inOrder.verify(writer1).update(iid, dataObject, dataObject, ctx);
+        inOrder.verify(writer2).update(iid2, dataObject2, dataObject2, ctx);
+
+        verifyNoMoreInteractions(writer1);
+        verifyNoMoreInteractions(writer2);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testMultipleUpdatesOneMissing() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        addUpdate(updates, DataObject1.class);
+        addUpdate(updates, DataObject2.class);
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailing() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
+
+        // Writer1 always fails
+        doThrow(new RuntimeException()).when(writer1)
+                .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        addUpdate(updates, DataObject1.class);
+        addUpdate(updates, DataObject2.class);
+
+        try {
+            flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+            fail("Bulk update should have failed on writer1");
+        } catch (WriterRegistry.BulkUpdateException e) {
+            assertThat(e.getFailedIds().size(), is(2));
+            assertThat(e.getFailedIds(), hasItem(InstanceIdentifier.create(DataObject2.class)));
+            assertThat(e.getFailedIds(), hasItem(InstanceIdentifier.create(DataObject1.class)));
+        }
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailingThenRevertWithSuccess() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(
+                        ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2, DataObject3.IID, writer3));
+
+        // Writer1 always fails
+        doThrow(new RuntimeException()).when(writer3)
+                .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        addUpdate(updates, DataObject1.class);
+        addUpdate(updates, DataObject3.class);
+        final InstanceIdentifier<DataObject2> iid2 = InstanceIdentifier.create(DataObject2.class);
+        final DataObject2 before2 = mock(DataObject2.class);
+        final DataObject2 after2 = mock(DataObject2.class);
+        updates.put(DataObject2.IID, DataObjectUpdate.create(iid2, before2, after2));
+
+        try {
+            flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+            fail("Bulk update should have failed on writer1");
+        } catch (WriterRegistry.BulkUpdateException e) {
+            assertThat(e.getFailedIds().size(), is(1));
+
+            final InOrder inOrder = inOrder(writer1, writer2, writer3);
+            inOrder.verify(writer1)
+                .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+            inOrder.verify(writer2)
+                .update(iid2, before2, after2, ctx);
+            inOrder.verify(writer3)
+                .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+
+            e.revertChanges();
+            // Revert changes. Successful updates are iterated in reverse
+            inOrder.verify(writer2)
+                    .update(iid2, after2, before2, ctx);
+            inOrder.verify(writer1)
+                    .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+            verifyNoMoreInteractions(writer3);
+        }
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailingThenRevertWithFail() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(
+                        ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2, DataObject3.IID, writer3));
+
+        // Writer1 always fails
+        doThrow(new RuntimeException()).when(writer3)
+                .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        addUpdate(updates, DataObject1.class);
+        addUpdate(updates, DataObject2.class);
+        addUpdate(updates, DataObject3.class);
+
+        try {
+            flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+            fail("Bulk update should have failed on writer1");
+        } catch (WriterRegistry.BulkUpdateException e) {
+            // Writer1 always fails from now
+            doThrow(new RuntimeException()).when(writer1)
+                    .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), any(WriteContext.class));
+            try {
+                e.revertChanges();
+            } catch (WriterRegistry.Reverter.RevertFailedException e1) {
+                assertThat(e1.getNotRevertedChanges().size(), is(1));
+                assertThat(e1.getNotRevertedChanges(), hasItem(InstanceIdentifier.create(DataObject1.class)));
+            }
+        }
+    }
+
+    private <D extends DataObject> void addUpdate(final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates,
+                           final Class<D> type) throws Exception {
+        final InstanceIdentifier<D> iid = (InstanceIdentifier<D>) type.getDeclaredField("IID").get(null);
+        updates.put(iid, DataObjectUpdate.create(iid, mock(type), mock(type)));
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void testSingleUpdateMissingWriter() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of());
+
+        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
+        final DataObject1 before = mock(DataObject1.class);
+        final DataObject1 after = mock(DataObject1.class);
+        flatWriterRegistry.update(iid, before, after, ctx);
+    }
+
+    private abstract static class DataObject1 implements DataObject {
+        static final InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
+    }
+    private abstract static class DataObject2 implements DataObject {
+        static final InstanceIdentifier<DataObject2> IID = InstanceIdentifier.create(DataObject2.class);
+    }
+    private abstract static class DataObject3 implements DataObject {
+        static final InstanceIdentifier<DataObject3> IID = InstanceIdentifier.create(DataObject3.class);
+    }
+}
\ No newline at end of file
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/SubtreeWriterTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/SubtreeWriterTest.java
new file mode 100644
index 000000000..b7dcadc73
--- /dev/null
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/SubtreeWriterTest.java
@@ -0,0 +1,96 @@
+/*
+ * 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.translate.util.write.registry;
+
+import static org.hamcrest.CoreMatchers.hasItem;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.v3po.translate.write.Writer;
+import java.util.Collections;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.yang.binding.ChildOf;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class SubtreeWriterTest {
+
+    @Mock
+    Writer<DataObject1> writer;
+    @Mock
+    Writer<DataObject1.DataObject11> writer11;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        when(writer.getManagedDataObjectType()).thenReturn(DataObject1.IID);
+        when(writer11.getManagedDataObjectType()).thenReturn(DataObject1.DataObject11.IID);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testSubtreeWriterCreationFail() throws Exception {
+        // The subtree node identified by IID.c(DataObject.class) is not a child of writer.getManagedDataObjectType
+        SubtreeWriter.createForWriter(Collections.singleton(InstanceIdentifier.create(DataObject.class)), writer);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testSubtreeWriterCreationFailInvalidIid() throws Exception {
+        // The subtree node identified by IID.c(DataObject.class) is not a child of writer.getManagedDataObjectType
+        SubtreeWriter.createForWriter(Collections.singleton(DataObject1.IID), writer);
+    }
+
+    @Test
+    public void testSubtreeWriterCreation() throws Exception {
+        final SubtreeWriter<?> forWriter = (SubtreeWriter<?>) SubtreeWriter.createForWriter(Sets.newHashSet(
+                DataObject1.DataObject11.IID,
+                DataObject1.DataObject11.DataObject111.IID,
+                DataObject1.DataObject12.IID),
+                writer);
+
+        assertEquals(writer.getManagedDataObjectType(), forWriter.getManagedDataObjectType());
+        assertEquals(3, forWriter.getHandledChildTypes().size());
+    }
+
+    @Test
+    public void testSubtreeWriterHandledTypes() throws Exception {
+        final SubtreeWriter<?> forWriter = (SubtreeWriter<?>) SubtreeWriter.createForWriter(Sets.newHashSet(
+                DataObject1.DataObject11.DataObject111.IID),
+                writer);
+
+        assertEquals(writer.getManagedDataObjectType(), forWriter.getManagedDataObjectType());
+        assertEquals(1, forWriter.getHandledChildTypes().size());
+        assertThat(forWriter.getHandledChildTypes(), hasItem(DataObject1.DataObject11.DataObject111.IID));
+    }
+
+    private abstract static class DataObject1 implements DataObject {
+        static InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
+        private abstract static class DataObject11 implements DataObject, ChildOf<DataObject1> {
+            static InstanceIdentifier<DataObject11> IID = DataObject1.IID.child(DataObject11.class);
+            private abstract static class DataObject111 implements DataObject, ChildOf<DataObject11> {
+                static InstanceIdentifier<DataObject111> IID = DataObject11.IID.child(DataObject111.class);
+            }
+        }
+        private abstract static class DataObject12 implements DataObject, ChildOf<DataObject1> {
+            static InstanceIdentifier<DataObject12> IID = DataObject1.IID.child(DataObject12.class);
+        }
+    }
+}
\ No newline at end of file