HONEYCOMB-270 Add isPresent() to Readers/Customizers

So that they can influence whether empty data is to be considered as present

+ Move registries implementations from util to impl
+ Introduce DelegatingReader trait
+ Extend GenericReader where possible to reduce duplication

Change-Id: I5a416acd0c4eab1fbc30fcbe585719991dbe9215
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

9 files changed, 1166 insertions, 2 deletions

diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/GenericListReaderTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/GenericListReaderTest.java
index 0dc916fb8..3ed400dba 100644
--- a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/GenericListReaderTest.java
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/GenericListReaderTest.java
@@ -25,7 +25,6 @@ import static org.mockito.Mockito.when;
 import com.google.common.collect.Lists;
 import io.fd.honeycomb.translate.read.ReadContext;
 import io.fd.honeycomb.translate.spi.read.ListReaderCustomizer;
-import java.util.Collections;
 import java.util.List;
 import org.junit.Before;
 import org.junit.Test;
@@ -78,7 +77,7 @@ public class GenericListReaderTest {
     @Test
     public void testMerge() throws Exception {
         reader.merge(builder, data);
-        verify(customizer).merge(builder, Collections.singletonList(data));
+        verify(customizer).merge(builder, data);
     }
 
     @Test
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryBuilderTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryBuilderTest.java
new file mode 100644
index 000000000..4dee8e60f
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryBuilderTest.java
@@ -0,0 +1,114 @@
+/*
+ * 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.translate.impl.read.registry;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import io.fd.honeycomb.translate.read.Reader;
+import io.fd.honeycomb.translate.read.registry.ReaderRegistry;
+import io.fd.honeycomb.translate.util.DataObjects;
+import java.util.List;
+import java.util.Map;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class CompositeReaderRegistryBuilderTest {
+
+    private Reader<DataObjects.DataObject1, Builder<DataObjects.DataObject1>> reader1 =
+            mock(DataObjects.DataObject1.class);
+    private Reader<DataObjects.DataObject2, Builder<DataObjects.DataObject2>> reader2 =
+            mock(DataObjects.DataObject2.class);
+    private Reader<DataObjects.DataObject3, Builder<DataObjects.DataObject3>> reader3 =
+            mock(DataObjects.DataObject3.class);
+    private Reader<DataObjects.DataObject3.DataObject31, Builder<DataObjects.DataObject3.DataObject31>> reader31 =
+            mock(DataObjects.DataObject3.DataObject31.class);
+
+    private Reader<DataObjects.DataObject4, Builder<DataObjects.DataObject4>> reader4 =
+            mock(DataObjects.DataObject4.class);
+    private Reader<DataObjects.DataObject4.DataObject41, Builder<DataObjects.DataObject4.DataObject41>> reader41 =
+            mock(DataObjects.DataObject4.DataObject41.class);
+    private Reader<DataObjects.DataObject4.DataObject41.DataObject411, Builder<DataObjects.DataObject4.DataObject41.DataObject411>> reader411 =
+            mock(DataObjects.DataObject4.DataObject41.DataObject411.class);
+    private Reader<DataObjects.DataObject4.DataObject42, Builder<DataObjects.DataObject4.DataObject42>> reader42 =
+            mock(DataObjects.DataObject4.DataObject42.class);
+
+    @SuppressWarnings("unchecked")
+    private <D extends DataObject> Reader<D, Builder<D>> mock(final Class<D> dataObjectType) {
+        final Reader<D, Builder<D>> mock = Mockito.mock(Reader.class);
+        try {
+            when(mock.getManagedDataObjectType())
+                    .thenReturn(((InstanceIdentifier<D>) dataObjectType.getDeclaredField("IID").get(null)));
+        } catch (IllegalAccessException | NoSuchFieldException e) {
+            throw new RuntimeException(e);
+        }
+        return mock;
+    }
+
+    @Test
+    public void testCompositeStructure() throws Exception {
+        final CompositeReaderRegistryBuilder compositeReaderRegistryBuilder = new CompositeReaderRegistryBuilder();
+        /*
+            Composite reader structure ordered left from right
+
+            1,      2,      3,      4
+                            31      42, 41
+                                        411
+         */
+        compositeReaderRegistryBuilder.add(reader1);
+        compositeReaderRegistryBuilder.addAfter(reader2, reader1.getManagedDataObjectType());
+        compositeReaderRegistryBuilder.addAfter(reader3, reader2.getManagedDataObjectType());
+        compositeReaderRegistryBuilder.addAfter(reader31, reader1.getManagedDataObjectType());
+        compositeReaderRegistryBuilder.addAfter(reader4, reader3.getManagedDataObjectType());
+        compositeReaderRegistryBuilder.add(reader41);
+        compositeReaderRegistryBuilder.addBefore(reader42, reader41.getManagedDataObjectType());
+        compositeReaderRegistryBuilder.add(reader411);
+
+        final ReaderRegistry build = compositeReaderRegistryBuilder.build();
+
+        final Map<Class<? extends DataObject>, Reader<? extends DataObject, ? extends Builder<?>>> rootReaders =
+                ((CompositeReaderRegistry) build).getRootReaders();
+        final List<Class<? extends DataObject>> rootReaderOrder = Lists.newArrayList(rootReaders.keySet());
+
+        assertEquals(reader1.getManagedDataObjectType().getTargetType(), rootReaderOrder.get(0));
+        assertEquals(reader2.getManagedDataObjectType().getTargetType(), rootReaderOrder.get(1));
+        assertEquals(reader3.getManagedDataObjectType().getTargetType(), rootReaderOrder.get(2));
+        assertEquals(reader4.getManagedDataObjectType().getTargetType(), rootReaderOrder.get(3));
+
+        assertFalse(rootReaders.get(DataObjects.DataObject1.class) instanceof CompositeReader);
+        assertFalse(rootReaders.get(DataObjects.DataObject2.class) instanceof CompositeReader);
+        assertTrue(rootReaders.get(DataObjects.DataObject3.class) instanceof CompositeReader);
+        assertTrue(rootReaders.get(DataObjects.DataObject4.class) instanceof CompositeReader);
+
+        final ImmutableMap<Class<?>, Reader<? extends DataObject, ? extends Builder<?>>> childReaders =
+                ((CompositeReader<? extends DataObject, ? extends Builder<?>>) rootReaders
+                        .get(DataObjects.DataObject4.class)).getChildReaders();
+        final List<Class<?>> orderedChildReaders = Lists.newArrayList(childReaders.keySet());
+
+        assertEquals(reader42.getManagedDataObjectType().getTargetType(), orderedChildReaders.get(0));
+        assertEquals(reader41.getManagedDataObjectType().getTargetType(), orderedChildReaders.get(1));
+        assertTrue(childReaders.get(DataObjects.DataObject4.DataObject41.class) instanceof CompositeReader);
+        assertFalse(childReaders.get(DataObjects.DataObject4.DataObject42.class) instanceof CompositeReader);
+    }
+}
\ No newline at end of file
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryTest.java
new file mode 100644
index 000000000..40068e02c
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderRegistryTest.java
@@ -0,0 +1,124 @@
+/*
+ * 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.translate.impl.read.registry;
+
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject3;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject3.DataObject31;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject4;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject4.DataObject41;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.Reader;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.InOrder;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class CompositeReaderRegistryTest {
+
+    @Mock
+    private ReadContext ctx;
+    private CompositeReaderRegistry reg;
+    private Reader<DataObject31, Builder<DataObject31>> reader31;
+    private Reader<DataObject3, Builder<DataObject3>> rootReader3;
+    private Reader<DataObject41, Builder<DataObject41>> reader41;
+    private Reader<DataObject4, Builder<DataObject4>> rootReader4;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+
+        reader31 = mockReader(DataObject31.class);
+        final Reader<DataObject3, Builder<DataObject3>> mockedReader3 = mockReader(DataObject3.class);
+        rootReader3 =
+                Mockito.spy(CompositeReader.createForReader(
+                        mockedReader3,
+                        ImmutableMap.of(DataObject31.class, reader31)));
+        // This is a workaround. This functionality is already present in CompositeReader, however when wrapping as spy
+        // null is always returned. That's why we need to explicitly stub the method with its actual implementation.
+        // The problem is that the method is inherited as default method from an interface and mockito's spy seems to
+        // have a problem there
+        doReturn(mockedReader3.getBuilder(InstanceIdentifier.create(DataObject3.class)))
+                .when(rootReader3).getBuilder(any(InstanceIdentifier.class));
+
+        reader41 = mockReader(DataObject41.class);
+        final Reader<DataObject4, Builder<DataObject4>> mockedReader4 = mockReader(DataObject4.class);
+        rootReader4 =
+                Mockito.spy(CompositeReader.createForReader(
+                        mockedReader4, ImmutableMap.of(
+                                DataObject41.class, reader41)));
+        // Workaround
+        doReturn(mockedReader4.getBuilder(InstanceIdentifier.create(DataObject4.class)))
+                .when(rootReader4).getBuilder(any(InstanceIdentifier.class));
+
+        reg = new CompositeReaderRegistry(Lists.newArrayList(rootReader3, rootReader4));
+    }
+
+    @Test
+    public void testReadAll() throws Exception {
+        reg.readAll(ctx);
+
+        // Invoked according to composite ordering
+        final InOrder inOrder = inOrder(rootReader3, rootReader4, reader31, reader41);
+        inOrder.verify(rootReader3).read(any(InstanceIdentifier.class), any(ReadContext.class));
+        inOrder.verify(reader31).read(any(InstanceIdentifier.class), any(ReadContext.class));
+        inOrder.verify(rootReader4).read(any(InstanceIdentifier.class), any(ReadContext.class));
+        inOrder.verify(reader41).read(any(InstanceIdentifier.class), any(ReadContext.class));
+    }
+
+    @Test
+    public void testReadSingleRoot() throws Exception {
+        reg.read(DataObject3.IID, ctx);
+
+        // Invoked according to composite ordering
+        final InOrder inOrder = inOrder(rootReader3, rootReader4, reader31, reader41);
+        inOrder.verify(rootReader3).read(any(InstanceIdentifier.class), any(ReadContext.class));
+        inOrder.verify(reader31).read(any(InstanceIdentifier.class), any(ReadContext.class));
+
+        // Only subtree under DataObject3 should be read
+        verify(rootReader4, times(0)).read(any(InstanceIdentifier.class), any(ReadContext.class));
+        verify(reader41, times(0)).read(any(InstanceIdentifier.class), any(ReadContext.class));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <D extends DataObject, B extends Builder<D>> Reader<D, B> mockReader(final Class<D> dataType)
+            throws Exception {
+        final Reader r = mock(Reader.class);
+        final Object iid = dataType.getDeclaredField("IID").get(null);
+        when(r.getManagedDataObjectType()).thenReturn((InstanceIdentifier) iid);
+        final Builder builder = mock(Builder.class);
+        when(builder.build()).thenReturn(mock(dataType));
+        when(r.getBuilder(any(InstanceIdentifier.class))).thenReturn(builder);
+        when(r.read(any(InstanceIdentifier.class), any(ReadContext.class))).thenReturn(Optional.of(mock(dataType)));
+        return (Reader<D, B>) r;
+    }
+}
\ No newline at end of file
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderTest.java
new file mode 100644
index 000000000..8d4bdadda
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/CompositeReaderTest.java
@@ -0,0 +1,124 @@
+/*
+ * 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.translate.impl.read.registry;
+
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject4;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObject4.DataObject41;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObjectK;
+import static io.fd.honeycomb.translate.util.DataObjects.DataObjectKey;
+import static io.fd.honeycomb.translate.impl.read.registry.CompositeReaderRegistryTest.mockReader;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import io.fd.honeycomb.translate.read.ListReader;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.Reader;
+import io.fd.honeycomb.translate.util.DataObjects;
+import java.util.List;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.Identifiable;
+import org.opendaylight.yangtools.yang.binding.Identifier;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class CompositeReaderTest {
+
+    @Mock
+    private ReadContext ctx;
+    private Reader<DataObject41, Builder<DataObject41>> reader41;
+    private Reader<DataObject4, Builder<DataObject4>> reader4;
+    private Reader<DataObject4, Builder<DataObject4>> compositeReader;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+
+        reader41 = mockReader(DataObject41.class);
+        reader4 = mockReader(DataObject4.class);
+        compositeReader = CompositeReader
+                .createForReader(reader4, ImmutableMap.of(DataObject41.class, reader41));
+    }
+
+    @Test
+    public void testReadCurrent() throws Exception {
+        compositeReader.read(DataObject4.IID, ctx);
+        verify(reader4).readCurrentAttributes(eq(DataObject4.IID), any(Builder.class), eq(ctx));
+        verify(reader41).read(DataObject41.IID, ctx);
+    }
+
+    @Test
+    public void testReadJustChild() throws Exception {
+        // Delegating read to child
+        compositeReader.read(DataObject41.IID, ctx);
+        verify(reader4, times(0))
+                .readCurrentAttributes(any(InstanceIdentifier.class), any(Builder.class), any(ReadContext.class));
+        verify(reader41).read(DataObject41.IID, ctx);
+    }
+
+    @Test
+    public void testReadFallback() throws Exception {
+        // Delegating read to delegate as a fallback since IID does not fit, could be handled by the delegate if its
+        // a subtree handler
+        compositeReader.read(DataObjects.DataObject4.DataObject42.IID, ctx);
+        verify(reader4).read(DataObjects.DataObject4.DataObject42.IID, ctx);
+        verify(reader41, times(0)).read(any(InstanceIdentifier.class), any(ReadContext.class));
+    }
+
+    @Test
+    public void testList() throws Exception {
+        final Reader<DataObjectK.DataObjectK1, Builder<DataObjectK.DataObjectK1>> readerK1 =
+                mockReader(DataObjectK.DataObjectK1.class);
+        final ListReader<DataObjectK, DataObjectKey, Builder<DataObjectK>> readerK =
+                mockListReader(DataObjectK.class, Lists.newArrayList(new DataObjectKey(), new DataObjectKey()));
+        final ListReader<DataObjectK, DataObjectKey, Builder<DataObjectK>>
+                compositeReaderK = (ListReader<DataObjectK, DataObjectKey, Builder<DataObjectK>>)
+                CompositeReader.createForReader(readerK, ImmutableMap.of(DataObject41.class, readerK1));
+
+        compositeReaderK.readList(DataObjectK.IID, ctx);
+
+        verify(readerK).getAllIds(DataObjectK.IID, ctx);
+        verify(readerK, times(2))
+                .readCurrentAttributes(any(InstanceIdentifier.class), any(Builder.class), any(ReadContext.class));
+    }
+
+    @SuppressWarnings("unchecked")
+    static <D extends DataObject & Identifiable<K>, K extends Identifier<D>, B extends Builder<D>> ListReader<D, K, B> mockListReader(
+            final Class<D> dataType, List<K> keys)
+            throws Exception {
+        final ListReader r = mock(ListReader.class);
+        final Object iid = dataType.getDeclaredField("IID").get(null);
+        when(r.getManagedDataObjectType()).thenReturn((InstanceIdentifier) iid);
+        final Builder builder = mock(Builder.class);
+        when(builder.build()).thenReturn(mock(dataType));
+        when(r.getBuilder(any(InstanceIdentifier.class))).thenReturn(builder);
+        when(r.read(any(InstanceIdentifier.class), any(ReadContext.class))).thenReturn(Optional.of(mock(dataType)));
+        when(r.getAllIds(any(InstanceIdentifier.class), any(ReadContext.class))).thenReturn(keys);
+        return (ListReader<D, K, B>) r;
+    }
+
+}
\ No newline at end of file
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/SubtreeReaderTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/SubtreeReaderTest.java
new file mode 100644
index 000000000..d2375e6be
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/SubtreeReaderTest.java
@@ -0,0 +1,125 @@
+/*
+ * 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.translate.impl.read.registry;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.mockito.Mockito.atLeastOnce;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.Reader;
+import io.fd.honeycomb.translate.util.DataObjects;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.ChildOf;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class SubtreeReaderTest {
+
+    @Mock
+    private Reader<DataObjects.DataObject4, Builder<DataObjects.DataObject4>> delegate;
+    @Mock
+    private Reader<DataObject1, Builder<DataObject1>> delegateLocal;
+    @Mock
+    private ReadContext ctx;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        Mockito.doReturn(DataObjects.DataObject4.IID).when(delegate).getManagedDataObjectType();
+        doReturn(DataObject1.IID).when(delegateLocal).getManagedDataObjectType();
+    }
+
+    @Test
+    public void testCreate() throws Exception {
+        final Reader<DataObjects.DataObject4, Builder<DataObjects.DataObject4>> subtreeR =
+                SubtreeReader.createForReader(Sets.newHashSet(DataObjects.DataObject4.DataObject41.IID), delegate);
+
+        subtreeR.getBuilder(DataObjects.DataObject4.IID);
+        verify(delegate).getBuilder(DataObjects.DataObject4.IID);
+
+        subtreeR.getManagedDataObjectType();
+        verify(delegate, atLeastOnce()).getManagedDataObjectType();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testCreateInvalid() throws Exception {
+        SubtreeReader.createForReader(Sets.newHashSet(DataObjects.DataObject1.IID), delegate);
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testReadOnlySubtreeCannotFilter() throws Exception {
+        final Reader<DataObjects.DataObject4, Builder<DataObjects.DataObject4>> subtreeR =
+                SubtreeReader.createForReader(Sets.newHashSet(DataObjects.DataObject4.DataObject41.IID), delegate);
+
+        doReturn(Optional.fromNullable(mock(DataObjects.DataObject4.class))).when(delegate).read(DataObjects.DataObject4.IID, ctx);
+        subtreeR.read(DataObjects.DataObject4.DataObject41.IID, ctx);
+    }
+
+    @Test
+    public void testReadOnlySubtreeNotPresent() throws Exception {
+        final Reader<DataObjects.DataObject4, Builder<DataObjects.DataObject4>> subtreeR =
+                SubtreeReader.createForReader(Sets.newHashSet(DataObjects.DataObject4.DataObject41.IID), delegate);
+
+        doReturn(Optional.absent()).when(delegate).read(DataObjects.DataObject4.IID, ctx);
+        assertFalse(subtreeR.read(DataObjects.DataObject4.DataObject41.IID, ctx).isPresent());
+    }
+
+    @Test
+    public void testReadOnlySubtreeChild() throws Exception {
+        final Reader<DataObject1, Builder<DataObject1>> subtreeR =
+                SubtreeReader.createForReader(Sets.newHashSet(DataObject1.DataObject11.IID), delegateLocal);
+
+        final DataObject1 mock = mock(DataObject1.class);
+        final DataObject1.DataObject11 mock11 = mock(DataObject1.DataObject11.class);
+        doReturn(mock11).when(mock).getDataObject11();
+        doReturn(Optional.fromNullable(mock)).when(delegateLocal).read(DataObject1.IID, ctx);
+        assertEquals(mock11, subtreeR.read(DataObject1.DataObject11.IID, ctx).get());
+    }
+
+    @Test
+    public void testReadEntireSubtree() throws Exception {
+        final Reader<DataObject1, Builder<DataObject1>> subtreeR =
+                SubtreeReader.createForReader(Sets.newHashSet(DataObject1.DataObject11.IID), delegateLocal);
+
+        final DataObject1 mock = mock(DataObject1.class);
+        final DataObject1.DataObject11 mock11 = mock(DataObject1.DataObject11.class);
+        doReturn(mock11).when(mock).getDataObject11();
+        doReturn(Optional.fromNullable(mock)).when(delegateLocal).read(DataObject1.IID, ctx);
+        assertEquals(mock, subtreeR.read(DataObject1.IID, ctx).get());
+    }
+
+    public abstract static class DataObject1 implements DataObject {
+        public static InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
+
+        public abstract DataObject11 getDataObject11();
+
+        public abstract static class DataObject11 implements DataObject, ChildOf<DataObject1> {
+            public static InstanceIdentifier<DataObject11> IID = DataObject1.IID.child(DataObject11.class);
+        }
+    }
+}
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/TypeHierarchyTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/TypeHierarchyTest.java
new file mode 100644
index 000000000..bbccc488b
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/read/registry/TypeHierarchyTest.java
@@ -0,0 +1,72 @@
+/*
+ * 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.translate.impl.read.registry;
+
+import static org.hamcrest.CoreMatchers.hasItem;
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.translate.util.DataObjects;
+import org.hamcrest.CoreMatchers;
+import org.junit.Test;
+
+public class TypeHierarchyTest {
+
+    @Test
+    public void testHierarchy() throws Exception {
+        final TypeHierarchy typeHierarchy = TypeHierarchy.create(Sets.newHashSet(
+                DataObjects.DataObject4.DataObject41.DataObject411.IID,
+                DataObjects.DataObject4.DataObject41.IID,/* Included in previous already */
+                DataObjects.DataObject1.IID,
+                DataObjects.DataObject3.DataObject31.IID));
+
+        // Roots
+        assertThat(typeHierarchy.getRoots().size(), is(3));
+        assertThat(typeHierarchy.getRoots(), CoreMatchers
+                .hasItems(DataObjects.DataObject1.IID, DataObjects.DataObject3.IID, DataObjects.DataObject4.IID));
+
+        // Leaves
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject1.IID).size(), is(0));
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject3.DataObject31.IID).size(), is(0));
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject4.DataObject41.DataObject411.IID).size(), is(0));
+
+        // Intermediate leaves
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject3.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject3.IID), CoreMatchers
+                .hasItem(DataObjects.DataObject3.DataObject31.IID));
+        assertEquals(typeHierarchy.getDirectChildren(DataObjects.DataObject3.IID), typeHierarchy.getAllChildren(
+                DataObjects.DataObject3.IID));
+
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject4.DataObject41.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject4.DataObject41.IID), CoreMatchers.hasItem(
+                DataObjects.DataObject4.DataObject41.DataObject411.IID));
+        assertEquals(typeHierarchy.getDirectChildren(DataObjects.DataObject4.DataObject41.IID), typeHierarchy.getAllChildren(
+                DataObjects.DataObject4.DataObject41.IID));
+
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject4.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObjects.DataObject4.IID), CoreMatchers
+                .hasItem(DataObjects.DataObject4.DataObject41.IID));
+        assertThat(typeHierarchy.getAllChildren(DataObjects.DataObject4.IID).size(), is(2));
+        assertTrue(typeHierarchy.getAllChildren(DataObjects.DataObject4.IID).contains(DataObjects.DataObject4.DataObject41.IID));
+        assertTrue(typeHierarchy.getAllChildren(DataObjects.DataObject4.IID).contains(DataObjects.DataObject4.DataObject41.DataObject411.IID));
+    }
+}
+
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryBuilderTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryBuilderTest.java
new file mode 100644
index 000000000..3a6767265
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryBuilderTest.java
@@ -0,0 +1,193 @@
+/*
+ * 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.translate.impl.write.registry;
+
+import static org.hamcrest.CoreMatchers.anyOf;
+import static org.hamcrest.CoreMatchers.equalTo;
+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.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Multimaps;
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.translate.util.DataObjects;
+import io.fd.honeycomb.translate.write.DataObjectUpdate;
+import io.fd.honeycomb.translate.write.WriteContext;
+import io.fd.honeycomb.translate.write.Writer;
+import io.fd.honeycomb.translate.write.registry.WriterRegistry;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import org.hamcrest.CoreMatchers;
+import org.junit.Test;
+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.add(mockWriter(DataObjects.DataObject3.class));
+        flatWriterRegistryBuilder.add(mockWriter(DataObjects.DataObject4.class));
+        flatWriterRegistryBuilder.addBefore(mockWriter(DataObjects.DataObject2.class),
+                Lists.newArrayList(DataObjects.DataObject3.IID, DataObjects.DataObject4.IID));
+        flatWriterRegistryBuilder.addBefore(mockWriter(DataObjects.DataObject1.class), DataObjects.DataObject2.IID);
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedHandlers();
+
+        final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+        assertEquals(DataObjects.DataObject1.IID, typesInList.get(0));
+        assertEquals(DataObjects.DataObject2.IID, typesInList.get(1));
+        assertThat(typesInList.get(2), anyOf(equalTo(DataObjects.DataObject3.IID), equalTo(DataObjects.DataObject4.IID)));
+        assertThat(typesInList.get(3), anyOf(equalTo(DataObjects.DataObject3.IID), equalTo(DataObjects.DataObject4.IID)));
+    }
+
+    @Test
+    public void testBuild() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        final Writer<? extends DataObject> writer = mockWriter(DataObjects.DataObject3.class);
+        flatWriterRegistryBuilder.add(writer);
+        final WriterRegistry build = flatWriterRegistryBuilder.build();
+
+        final InstanceIdentifier<DataObjects.DataObject3> id = InstanceIdentifier.create(DataObjects.DataObject3.class);
+        final DataObjectUpdate update = mock(DataObjectUpdate.class);
+        doReturn(id).when(update).getId();
+        final DataObjects.DataObject3 before = mock(DataObjects.DataObject3.class);
+        final DataObjects.DataObject3 after = mock(DataObjects.DataObject3.class);
+        when(update.getDataBefore()).thenReturn(before);
+        when(update.getDataAfter()).thenReturn(after);
+
+        WriterRegistry.DataObjectUpdates updates = new WriterRegistry.DataObjectUpdates(
+                Multimaps.forMap(Collections.singletonMap(id, update)),
+                Multimaps.forMap(Collections.emptyMap()));
+        final WriteContext ctx = mock(WriteContext.class);
+        build.update(updates, ctx);
+
+        verify(writer).update(id, before, after, ctx);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testBuildUnknownWriter() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        final Writer<? extends DataObject> writer = mockWriter(DataObjects.DataObject3.class);
+        flatWriterRegistryBuilder.add(writer);
+        final WriterRegistry build = flatWriterRegistryBuilder.build();
+
+        final InstanceIdentifier<DataObjects.DataObject1> id2 = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final DataObjectUpdate update2 = mock(DataObjectUpdate.class);
+        final WriterRegistry.DataObjectUpdates updates = new WriterRegistry.DataObjectUpdates(
+                Multimaps.forMap(Collections.singletonMap(id2, update2)),
+                Multimaps.forMap(Collections.emptyMap()));
+        build.update(updates, mock(WriteContext.class));
+    }
+
+    @Test
+    public void testRelationsAfter() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        /*
+            1   ->  2   ->  3
+                        ->  4
+         */
+        flatWriterRegistryBuilder.add(mockWriter(DataObjects.DataObject1.class));
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObjects.DataObject2.class), DataObjects.DataObject1.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObjects.DataObject3.class), DataObjects.DataObject2.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObjects.DataObject4.class),
+                Lists.newArrayList(DataObjects.DataObject2.IID, DataObjects.DataObject3.IID));
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedHandlers();
+
+        final List<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+        assertEquals(DataObjects.DataObject1.IID, typesInList.get(0));
+        assertEquals(DataObjects.DataObject2.IID, typesInList.get(1));
+        assertThat(typesInList.get(2), anyOf(equalTo(DataObjects.DataObject3.IID), equalTo(DataObjects.DataObject4.IID)));
+        assertThat(typesInList.get(3), anyOf(equalTo(DataObjects.DataObject3.IID), equalTo(DataObjects.DataObject4.IID)));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testRelationsLoop() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        /*
+            1   ->  2   ->  1
+         */
+        flatWriterRegistryBuilder.add(mockWriter(DataObjects.DataObject1.class));
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObjects.DataObject2.class), DataObjects.DataObject1.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObjects.DataObject1.class), DataObjects.DataObject2.IID);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testAddWriterTwice() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        flatWriterRegistryBuilder.add(mockWriter(DataObjects.DataObject1.class));
+        flatWriterRegistryBuilder.add(mockWriter(DataObjects.DataObject1.class));
+    }
+
+    @Test
+    public void testAddSubtreeWriter() throws Exception {
+        final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
+        flatWriterRegistryBuilder.subtreeAdd(
+                Sets.newHashSet(DataObjects.DataObject4.DataObject41.IID,
+                                DataObjects.DataObject4.DataObject41.IID),
+                mockWriter(DataObjects.DataObject4.class));
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
+                flatWriterRegistryBuilder.getMappedHandlers();
+        final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
+
+        assertEquals(DataObjects.DataObject4.IID, typesInList.get(0));
+        assertEquals(1, typesInList.size());
+    }
+
+    @Test
+    public void testCreateSubtreeWriter() throws Exception {
+        final Writer<?> forWriter = SubtreeWriter.createForWriter(Sets.newHashSet(
+                DataObjects.DataObject4.DataObject41.IID,
+                DataObjects.DataObject4.DataObject41.DataObject411.IID,
+                DataObjects.DataObject4.DataObject42.IID),
+                mockWriter(DataObjects.DataObject4.class));
+        assertThat(forWriter, instanceOf(SubtreeWriter.class));
+        assertThat(((SubtreeWriter<?>) forWriter).getHandledChildTypes().size(), is(3));
+        assertThat(((SubtreeWriter<?>) forWriter).getHandledChildTypes(), CoreMatchers.hasItems(DataObjects.DataObject4.DataObject41.IID,
+                DataObjects.DataObject4.DataObject42.IID, DataObjects.DataObject4.DataObject41.DataObject411.IID));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testCreateInvalidSubtreeWriter() throws Exception {
+        SubtreeWriter.createForWriter(Sets.newHashSet(
+                InstanceIdentifier.create(DataObjects.DataObject3.class).child(DataObjects.DataObject3.DataObject31.class)),
+                mockWriter(DataObjects.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;
+    }
+
+}
\ No newline at end of file
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryTest.java
new file mode 100644
index 000000000..65742df33
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/FlatWriterRegistryTest.java
@@ -0,0 +1,328 @@
+/*
+ * 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.translate.impl.write.registry;
+
+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.Matchers.eq;
+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.translate.util.DataObjects;
+import io.fd.honeycomb.translate.util.DataObjects.DataObject1;
+import io.fd.honeycomb.translate.write.DataObjectUpdate;
+import io.fd.honeycomb.translate.write.WriteContext;
+import io.fd.honeycomb.translate.write.Writer;
+import io.fd.honeycomb.translate.write.registry.WriterRegistry;
+import org.hamcrest.CoreMatchers;
+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<DataObjects.DataObject2> writer2;
+    @Mock
+    private Writer<DataObjects.DataObject3> writer3;
+    @Mock
+    private Writer<DataObjects.DataObject1ChildK> writer4;
+    @Mock
+    private WriteContext ctx;
+    @Mock
+    private WriteContext revertWriteContext;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        when(writer1.getManagedDataObjectType()).thenReturn(DataObjects.DataObject1.IID);
+        when(writer2.getManagedDataObjectType()).thenReturn(DataObjects.DataObject2.IID);
+        when(writer3.getManagedDataObjectType()).thenReturn(DataObjects.DataObject3.IID);
+    }
+
+    @Test
+    public void testMultipleUpdatesForSingleWriter() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObjects.DataObject1> iid = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final InstanceIdentifier<DataObjects.DataObject1> iid2 = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final DataObjects.DataObject1 dataObject = mock(DataObjects.DataObject1.class);
+        updates.put(DataObjects.DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        updates.put(DataObjects.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(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObjects.DataObject1> iid = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final DataObjects.DataObject1 dataObject = mock(DataObjects.DataObject1.class);
+        updates.put(DataObjects.DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        final InstanceIdentifier<DataObjects.DataObject2> iid2 = InstanceIdentifier.create(DataObjects.DataObject2.class);
+        final DataObjects.DataObject2 dataObject2 = mock(DataObjects.DataObject2.class);
+        updates.put(DataObjects.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(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate.DataObjectDelete> deletes = HashMultimap.create();
+        final InstanceIdentifier<DataObjects.DataObject1> iid = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final DataObjects.DataObject1 dataObject = mock(DataObjects.DataObject1.class);
+        deletes.put(DataObjects.DataObject1.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid, dataObject, null)));
+        final InstanceIdentifier<DataObjects.DataObject2> iid2 = InstanceIdentifier.create(DataObjects.DataObject2.class);
+        final DataObjects.DataObject2 dataObject2 = mock(DataObjects.DataObject2.class);
+        deletes.put(DataObjects.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(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate.DataObjectDelete> deletes = HashMultimap.create();
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        final InstanceIdentifier<DataObjects.DataObject1> iid = InstanceIdentifier.create(DataObjects.DataObject1.class);
+        final DataObjects.DataObject1 dataObject = mock(DataObjects.DataObject1.class);
+        // Writer 1 delete
+        deletes.put(DataObjects.DataObject1.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid, dataObject, null)));
+        // Writer 1 update
+        updates.put(DataObjects.DataObject1.IID, DataObjectUpdate.create(iid, dataObject, dataObject));
+        final InstanceIdentifier<DataObjects.DataObject2> iid2 = InstanceIdentifier.create(DataObjects.DataObject2.class);
+        final DataObjects.DataObject2 dataObject2 = mock(DataObjects.DataObject2.class);
+        // Writer 2 delete
+        deletes.put(DataObjects.DataObject2.IID, ((DataObjectUpdate.DataObjectDelete) DataObjectUpdate.create(iid2, dataObject2, null)));
+        // Writer 2 update
+        updates.put(DataObjects.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(DataObjects.DataObject1.IID, writer1));
+
+        final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates = HashMultimap.create();
+        addUpdate(updates, DataObjects.DataObject1.class);
+        addUpdate(updates, DataObjects.DataObject2.class);
+        flatWriterRegistry.update(new WriterRegistry.DataObjectUpdates(updates, ImmutableMultimap.of()), ctx);
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailing() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(ImmutableMap.of(DataObjects.DataObject1.IID, writer1, DataObjects.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, DataObjects.DataObject1.class);
+        addUpdate(updates, DataObjects.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(), CoreMatchers.hasItem(InstanceIdentifier.create(DataObjects.DataObject2.class)));
+            assertThat(e.getFailedIds(), CoreMatchers.hasItem(InstanceIdentifier.create(DataObjects.DataObject1.class)));
+        }
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailingThenRevertWithSuccess() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(
+                        ImmutableMap.of(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2, DataObjects.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, DataObjects.DataObject1.class);
+        addUpdate(updates, DataObjects.DataObject3.class);
+        final InstanceIdentifier<DataObjects.DataObject2> iid2 = InstanceIdentifier.create(DataObjects.DataObject2.class);
+        final DataObjects.DataObject2 before2 = mock(DataObjects.DataObject2.class);
+        final DataObjects.DataObject2 after2 = mock(DataObjects.DataObject2.class);
+        updates.put(DataObjects.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(revertWriteContext);
+            // Revert changes. Successful updates are iterated in reverse
+            // also binding other write context,to verify if update context is not reused
+            inOrder.verify(writer2)
+                    .update(iid2, after2, before2, revertWriteContext);
+            inOrder.verify(writer1)
+                    .update(any(InstanceIdentifier.class), any(DataObject.class), any(DataObject.class), eq(revertWriteContext));
+            verifyNoMoreInteractions(writer3);
+        }
+    }
+
+    @Test
+    public void testMultipleUpdatesOneFailingThenRevertWithFail() throws Exception {
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(
+                        ImmutableMap.of(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject2.IID, writer2, DataObjects.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, DataObjects.DataObject1.class);
+        addUpdate(updates, DataObjects.DataObject2.class);
+        addUpdate(updates, DataObjects.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(revertWriteContext);
+            } catch (WriterRegistry.Reverter.RevertFailedException e1) {
+                assertThat(e1.getNotRevertedChanges().size(), is(1));
+                assertThat(e1.getNotRevertedChanges(), CoreMatchers
+                        .hasItem(InstanceIdentifier.create(DataObjects.DataObject1.class)));
+            }
+        }
+    }
+
+    @Test
+    public void testMutlipleUpdatesWithOneKeyedContainer() throws Exception {
+        final InstanceIdentifier internallyKeyedIdentifier = InstanceIdentifier.create(DataObject1.class)
+                .child(DataObjects.DataObject1ChildK.class, new DataObjects.DataObject1ChildKey());
+
+        final FlatWriterRegistry flatWriterRegistry =
+                new FlatWriterRegistry(
+                        ImmutableMap.of(DataObjects.DataObject1.IID, writer1, DataObjects.DataObject1ChildK.IID,writer4));
+
+        // 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();
+        addKeyedUpdate(updates,DataObjects.DataObject1ChildK.class);
+        addUpdate(updates, DataObjects.DataObject1.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(revertWriteContext);
+            } catch (WriterRegistry.Reverter.RevertFailedException e1) {
+                assertThat(e1.getNotRevertedChanges().size(), is(1));
+                assertThat(e1.getNotRevertedChanges(), CoreMatchers
+                        .hasItem(InstanceIdentifier.create(DataObjects.DataObject1.class)));
+            }
+        }
+    }
+
+    private <D extends DataObject> void addKeyedUpdate(final Multimap<InstanceIdentifier<?>, DataObjectUpdate> updates,
+                                                       final Class<D> type) throws Exception {
+        final InstanceIdentifier<D> iid = (InstanceIdentifier<D>) type.getDeclaredField("IID").get(null);
+        final InstanceIdentifier<D> keyedIid = (InstanceIdentifier<D>) type.getDeclaredField("INTERNALLY_KEYED_IID").get(null);
+        updates.put(iid, DataObjectUpdate.create(keyedIid, mock(type), mock(type)));
+    }
+
+    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)));
+    }
+}
\ No newline at end of file
diff --git a/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/SubtreeWriterTest.java b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/SubtreeWriterTest.java
new file mode 100644
index 000000000..ff2f83158
--- /dev/null
+++ b/infra/translate-impl/src/test/java/io/fd/honeycomb/translate/impl/write/registry/SubtreeWriterTest.java
@@ -0,0 +1,85 @@
+/*
+ * 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.translate.impl.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.translate.util.DataObjects;
+import io.fd.honeycomb.translate.write.Writer;
+import java.util.Collections;
+import org.hamcrest.CoreMatchers;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class SubtreeWriterTest {
+
+    @Mock
+    Writer<DataObjects.DataObject4> writer;
+    @Mock
+    Writer<DataObjects.DataObject4.DataObject41> writer11;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+        when(writer.getManagedDataObjectType()).thenReturn(DataObjects.DataObject4.IID);
+        when(writer11.getManagedDataObjectType()).thenReturn(DataObjects.DataObject4.DataObject41.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(DataObjects.DataObject4.IID), writer);
+    }
+
+    @Test
+    public void testSubtreeWriterCreation() throws Exception {
+        final SubtreeWriter<?> forWriter = (SubtreeWriter<?>) SubtreeWriter.createForWriter(Sets.newHashSet(
+                DataObjects.DataObject4.DataObject41.IID,
+                DataObjects.DataObject4.DataObject41.DataObject411.IID,
+                DataObjects.DataObject4.DataObject42.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(
+                DataObjects.DataObject4.DataObject41.DataObject411.IID),
+                writer);
+
+        assertEquals(writer.getManagedDataObjectType(), forWriter.getManagedDataObjectType());
+        assertEquals(1, forWriter.getHandledChildTypes().size());
+        assertThat(forWriter.getHandledChildTypes(), CoreMatchers.hasItem(DataObjects.DataObject4.DataObject41.DataObject411.IID));
+    }
+
+}
\ No newline at end of file