HONEYCOMB-431: add support for <validate> RPC

This patch introduces ValidableTransaction interface,
used by Honeycomb's DataBroker to implement
Netconf's DOMDataTransactionValidator.

WriteTransaction implements ValidableTransaction
by delegating validate to DataModification
for both config and operational modifications.

This patch requires ODL Fluorine (HONEYCOMB-433),
which brings support for <candidate> validation to Netconf.
Alternatively custom ODL Oxygen build
with patches from stable/oxygen/oxygen-hc-improvements.

Change-Id: Ic3eaffaef0314d22da3ea37f9416f18ccb0b99ae
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>
Signed-off-by: Michal Cmarada <mcmarada@cisco.com>

15 files changed, 470 insertions, 22 deletions

diff --git a/infra/data-impl/pom.xml b/infra/data-impl/pom.xml
index 6abc1892d..fa6e11704 100644
--- a/infra/data-impl/pom.xml
+++ b/infra/data-impl/pom.xml
@@ -62,6 +62,10 @@
             <groupId>org.opendaylight.controller</groupId>
             <artifactId>sal-core-spi</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.opendaylight.netconf</groupId>
+            <artifactId>mdsal-netconf-connector</artifactId>
+        </dependency>
 
         <dependency>
             <groupId>junit</groupId>
@@ -83,6 +87,18 @@
             <artifactId>yang-test-util</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>xmlunit</groupId>
+            <artifactId>xmlunit</artifactId>
+            <version>1.6</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.opendaylight.netconf</groupId>
+            <artifactId>netconf-util</artifactId>
+            <type>test-jar</type>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
diff --git a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/DataBroker.java b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/DataBroker.java
index a60bf3415..1952f8778 100644
--- a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/DataBroker.java
+++ b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/DataBroker.java
@@ -33,6 +33,7 @@ import org.opendaylight.controller.md.sal.dom.api.DOMDataReadOnlyTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataReadWriteTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMTransactionChain;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -81,7 +82,10 @@ public class DataBroker implements DOMDataBroker, Closeable {
     @Nonnull
     @Override
     public Map<Class<? extends DOMDataBrokerExtension>, DOMDataBrokerExtension> getSupportedExtensions() {
-        return Collections.emptyMap();
+        return Collections.singletonMap(
+            DOMDataTransactionValidator.class,
+            (DOMDataTransactionValidator) tx -> ((ValidableTransaction)tx).validate()
+        );
     }
 
     /**
diff --git a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ReadWriteTransaction.java b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ReadWriteTransaction.java
index f26810e15..c7d54f0ec 100644
--- a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ReadWriteTransaction.java
+++ b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ReadWriteTransaction.java
@@ -31,6 +31,7 @@ import org.opendaylight.controller.md.sal.dom.api.DOMDataReadTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataReadWriteTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
 import org.opendaylight.mdsal.common.api.CommitInfo;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 import org.slf4j.Logger;
@@ -40,15 +41,15 @@ import org.slf4j.LoggerFactory;
  * Composite DOM transaction that delegates reads to a {@link DOMDataReadTransaction} delegate and writes to a {@link
  * DOMDataWriteTransaction} delegate.
  */
-final class ReadWriteTransaction implements DOMDataReadWriteTransaction {
+final class ReadWriteTransaction implements DOMDataReadWriteTransaction, ValidableTransaction {
 
     private static final Logger LOG = LoggerFactory.getLogger(ReadWriteTransaction.class);
 
     private final DOMDataReadOnlyTransaction delegateReadTx;
-    private final DOMDataWriteTransaction delegateWriteTx;
+    private final ValidableTransaction delegateWriteTx;
 
     ReadWriteTransaction(@Nonnull final DOMDataReadOnlyTransaction delegateReadTx,
-                         @Nonnull final DOMDataWriteTransaction delegateWriteTx) {
+                         @Nonnull final ValidableTransaction delegateWriteTx) {
         this.delegateReadTx = Preconditions.checkNotNull(delegateReadTx, "delegateReadTx should not be null");
         this.delegateWriteTx = Preconditions.checkNotNull(delegateWriteTx, "delegateWriteTx should not be null");
     }
@@ -111,5 +112,10 @@ final class ReadWriteTransaction implements DOMDataReadWriteTransaction {
     public Object getIdentifier() {
         return this;
     }
+
+    @Override
+    public CheckedFuture<Void, DOMDataTransactionValidator.ValidationFailedException> validate() {
+        return delegateWriteTx.validate();
+    }
 }
 
diff --git a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ValidableTransaction.java b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ValidableTransaction.java
new file mode 100644
index 000000000..0c67f863f
--- /dev/null
+++ b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/ValidableTransaction.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2018 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.data.impl;
+
+import com.google.common.annotations.Beta;
+import com.google.common.util.concurrent.CheckedFuture;
+import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator.ValidationFailedException;
+
+/**
+ * An {@link DOMDataWriteTransaction} than can be validated.
+ * @see DOMDataTransactionValidator
+ */
+@Beta
+interface ValidableTransaction extends DOMDataWriteTransaction {
+    /**
+     * Validates state of the data tree associated with the provided {@link DOMDataWriteTransaction}.
+     *
+     * <p>The operation should not have any side-effects on the transaction state.
+     *
+     * <p>It can be executed many times, providing the same results
+     * if the state of the transaction has not been changed.
+     *
+     * @return
+     *     a CheckedFuture containing the result of the validate operation. The future blocks until the validation
+     *     operation is complete. A successful validate returns nothing. On failure, the Future will fail
+     *     with a {@link ValidationFailedException} or an exception derived from ValidationFailedException.
+     */
+    CheckedFuture<Void, ValidationFailedException> validate();
+}
diff --git a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/WriteTransaction.java b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/WriteTransaction.java
index b2ed5265f..91b48cc10 100644
--- a/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/WriteTransaction.java
+++ b/infra/data-impl/src/main/java/io/fd/honeycomb/data/impl/WriteTransaction.java
@@ -32,7 +32,7 @@ import javax.annotation.concurrent.NotThreadSafe;
 import org.eclipse.jdt.annotation.NonNull;
 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator;
 import org.opendaylight.mdsal.common.api.CommitInfo;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
@@ -40,7 +40,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 @NotThreadSafe
-final class WriteTransaction implements DOMDataWriteTransaction {
+final class WriteTransaction implements ValidableTransaction {
 
     private static final Logger LOG = LoggerFactory.getLogger(WriteTransaction.class);
 
@@ -120,7 +120,7 @@ final class WriteTransaction implements DOMDataWriteTransaction {
         checkIsNew();
 
         try {
-            validateAndCommit();
+            doCommit();
         } catch (Exception e) {
             status = TransactionStatus.FAILED;
             LOG.error("Submit failed", e);
@@ -130,16 +130,8 @@ final class WriteTransaction implements DOMDataWriteTransaction {
         return Futures.immediateCheckedFuture(null);
     }
 
-    private void validateAndCommit() throws TranslationException {
+    private void doCommit() throws TranslationException {
         status = TransactionStatus.SUBMITED;
-        // Validate first to catch any issues before attempting commit
-        if (configModification != null) {
-            configModification.validate();
-        }
-        if (operationalModification != null) {
-            operationalModification.validate();
-        }
-
         if (configModification != null) {
             configModification.commit();
         }
@@ -155,7 +147,7 @@ final class WriteTransaction implements DOMDataWriteTransaction {
         LOG.trace("WriteTransaction.commit()");
         checkIsNew();
         try {
-            validateAndCommit();
+            doCommit();
         } catch (Exception e) {
             status = TransactionStatus.FAILED;
             LOG.error("Submit failed", e);
@@ -171,6 +163,21 @@ final class WriteTransaction implements DOMDataWriteTransaction {
         return this;
     }
 
+    @Override
+    public CheckedFuture<Void, DOMDataTransactionValidator.ValidationFailedException> validate() {
+        try {
+            if (configModification != null) {
+                configModification.validate();
+            }
+            if (operationalModification != null) {
+                operationalModification.validate();
+            }
+        } catch (Exception e) {
+            return Futures.immediateFailedCheckedFuture(new DOMDataTransactionValidator.ValidationFailedException(e.getMessage(), e.getCause()));
+        }
+        return Futures.immediateCheckedFuture(null);
+    }
+
 
     @Nonnull
     static WriteTransaction createOperationalOnly(@Nonnull final DataModification operationalData) {
@@ -188,7 +195,7 @@ final class WriteTransaction implements DOMDataWriteTransaction {
         return new WriteTransaction(requireNonNull(configData), requireNonNull(operationalData));
     }
 
-    // TODO consider removing because original class was deprecated and removed, this is just temporary fix.
+    // TODO consider refactor based on implemented contract.
     enum TransactionStatus {
         /**
          * The transaction has been freshly allocated. The user is still accessing
diff --git a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/DataBrokerTest.java b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/DataBrokerTest.java
index 14d32784f..124179c79 100644
--- a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/DataBrokerTest.java
+++ b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/DataBrokerTest.java
@@ -16,6 +16,8 @@
 
 package io.fd.honeycomb.data.impl;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -34,6 +36,7 @@ import org.opendaylight.controller.md.sal.common.api.data.TransactionChainListen
 import org.opendaylight.controller.md.sal.dom.api.DOMDataBrokerExtension;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataReadOnlyTransaction;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataReadWriteTransaction;
+import org.opendaylight.netconf.mdsal.connector.DOMDataTransactionValidator;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 
 public class DataBrokerTest {
@@ -93,7 +96,8 @@ public class DataBrokerTest {
     public void testGetSupportedExtensions() {
         final Map<Class<? extends DOMDataBrokerExtension>, DOMDataBrokerExtension> supportedExtensions =
                 broker.getSupportedExtensions();
-        assertTrue(supportedExtensions.isEmpty());
+        assertEquals(1, supportedExtensions.size());
+        assertNotNull(supportedExtensions.get(DOMDataTransactionValidator.class));
     }
 
     public static class DataBrokerForContextTest {
diff --git a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ReadWriteTransactionTest.java b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ReadWriteTransactionTest.java
index 820d499be..bbe384289 100644
--- a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ReadWriteTransactionTest.java
+++ b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ReadWriteTransactionTest.java
@@ -25,7 +25,6 @@ import org.junit.Test;
 import org.mockito.Mock;
 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
 import org.opendaylight.controller.md.sal.dom.api.DOMDataReadOnlyTransaction;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
 
@@ -35,7 +34,7 @@ public class ReadWriteTransactionTest {
     private DOMDataReadOnlyTransaction readTx;
 
     @Mock
-    private DOMDataWriteTransaction writeTx;
+    private ValidableTransaction writeTx;
 
     private LogicalDatastoreType store;
 
diff --git a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ValidateTest.java b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ValidateTest.java
new file mode 100644
index 000000000..b2a3aa64d
--- /dev/null
+++ b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/ValidateTest.java
@@ -0,0 +1,217 @@
+/*
+ * Copyright (c) 2018 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.data.impl;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.when;
+import static org.mockito.MockitoAnnotations.initMocks;
+import static org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeConfiguration.DEFAULT_CONFIGURATION;
+
+import com.google.common.io.ByteSource;
+import com.google.common.util.concurrent.Futures;
+import io.fd.honeycomb.data.ModifiableDataManager;
+import io.fd.honeycomb.data.ReadableDataManager;
+import java.io.StringWriter;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
+import org.custommonkey.xmlunit.DetailedDiff;
+import org.custommonkey.xmlunit.Diff;
+import org.custommonkey.xmlunit.XMLUnit;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.opendaylight.mdsal.dom.api.DOMSchemaService;
+import org.opendaylight.netconf.api.DocumentedException;
+import org.opendaylight.netconf.api.xml.XmlUtil;
+import org.opendaylight.netconf.mapping.api.NetconfOperation;
+import org.opendaylight.netconf.mapping.api.NetconfOperationChainedExecution;
+import org.opendaylight.netconf.mdsal.connector.CurrentSchemaContext;
+import org.opendaylight.netconf.mdsal.connector.TransactionProvider;
+import org.opendaylight.netconf.mdsal.connector.ops.Commit;
+import org.opendaylight.netconf.mdsal.connector.ops.EditConfig;
+import org.opendaylight.netconf.mdsal.connector.ops.Validate;
+import org.opendaylight.netconf.util.test.NetconfXmlUnitRecursiveQualifier;
+import org.opendaylight.netconf.util.test.XmlFileLoader;
+import org.opendaylight.yangtools.concepts.ListenerRegistration;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
+import org.opendaylight.yangtools.yang.data.impl.schema.tree.InMemoryDataTreeFactory;
+import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+import org.opendaylight.yangtools.yang.model.api.SchemaContextListener;
+import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
+import org.opendaylight.yangtools.yang.test.util.YangParserTestUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.w3c.dom.Document;
+
+public class ValidateTest {
+    private static final Logger LOG = LoggerFactory.getLogger(ValidateTest.class);
+    private static final String SESSION_ID_FOR_REPORTING = "netconf-test-session";
+    private static final Document RPC_REPLY_OK = getReplyOk();
+
+    @Mock
+    private DOMSchemaService schemaService;
+    @Mock
+    private ReadableDataManager operationalData;
+
+    private ModifiableDataManager configData;
+    private CurrentSchemaContext currentSchemaContext;
+    private DataBroker dataBroker;
+
+    @Before
+    public void setUp() throws Exception {
+        initMocks(this);
+        final DataTree dataTree = new InMemoryDataTreeFactory().create(DEFAULT_CONFIGURATION);
+        final SchemaContext schemaContext = YangParserTestUtils.parseYangResources(ValidateTest.class,
+            "/test-validate.yang");
+        when(schemaService.registerSchemaContextListener(any())).thenAnswer(invocation -> {
+            SchemaContextListener listener = invocation.getArgument(0);
+            listener.onGlobalContextUpdated(schemaContext);
+            return new ListenerRegistration<SchemaContextListener>() {
+                @Override
+                public void close() {
+                }
+
+                @Override
+                public SchemaContextListener getInstance() {
+                    return listener;
+                }
+            };
+        });
+        currentSchemaContext = new CurrentSchemaContext(schemaService, sourceIdentifier -> {
+            final YangTextSchemaSource yangTextSchemaSource =
+                YangTextSchemaSource.delegateForByteSource(sourceIdentifier, ByteSource.wrap("module test".getBytes()));
+            return Futures.immediateCheckedFuture(yangTextSchemaSource);
+        });
+        dataTree.setSchemaContext(schemaContext);
+        configData = new ModifiableDataTreeManager(dataTree);
+        dataBroker = DataBroker.create(configData, operationalData);
+        XMLUnit.setIgnoreWhitespace(true);
+        XMLUnit.setIgnoreAttributeOrder(true);
+    }
+
+    @Test
+    public void testValidate() throws Exception {
+        verifyResponse(validate("messages/validate/validate.xml"));
+    }
+
+    @Test
+    public void testValidateMissingMandatoryNode() throws Exception {
+        final TransactionProvider transactionProvider = new TransactionProvider(dataBroker, SESSION_ID_FOR_REPORTING);
+        verifyResponse(edit("messages/validate/edit-config-missing-mandatory-node.xml", transactionProvider));
+        try {
+            verifyResponse(commit(transactionProvider));
+            fail("Should have failed due to missing mandatory node");
+        } catch (DocumentedException e) {
+            assertTrue(e.getMessage().contains("missing mandatory descendant"));
+        }
+    }
+
+    @Test
+    public void testValidateAndCommit() throws Exception {
+        final TransactionProvider transactionProvider = new TransactionProvider(dataBroker, SESSION_ID_FOR_REPORTING);
+        verifyResponse(edit("messages/validate/edit-config-create-top-container.xml", transactionProvider));
+        verifyResponse(validate("messages/validate/validate.xml", transactionProvider));
+        verifyResponse(commit(transactionProvider));
+    }
+
+    @Test
+    public void testValidateTwice() throws Exception {
+        final TransactionProvider transactionProvider = initCandidateTransaction();
+        verifyResponse(validate("messages/validate/validate.xml", transactionProvider));
+        verifyResponse(validate("messages/validate/validate.xml", transactionProvider));
+    }
+
+    @SuppressWarnings("illegalCatch")
+    private static Document getReplyOk() {
+        Document doc;
+        try {
+            doc = XmlFileLoader.xmlFileToDocument("messages/rpc-reply_ok.xml");
+        } catch (final Exception e) {
+            LOG.debug("unable to load rpc reply ok.", e);
+            doc = XmlUtil.newDocument();
+        }
+        return doc;
+    }
+
+    private static void verifyResponse(final Document actual) throws Exception {
+        final DetailedDiff dd = new DetailedDiff(new Diff(RPC_REPLY_OK, actual));
+        dd.overrideElementQualifier(new NetconfXmlUnitRecursiveQualifier());
+        if (!dd.similar()) {
+            LOG.warn("Actual response:");
+            printDocument(actual);
+            LOG.warn("Expected response:");
+            printDocument(RPC_REPLY_OK);
+            fail("Differences found: " + dd.toString());
+        }
+    }
+
+    private static void printDocument(final Document doc) throws Exception {
+        final TransformerFactory tf = TransformerFactory.newInstance();
+        final Transformer transformer = tf.newTransformer();
+        transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "no");
+        transformer.setOutputProperty(OutputKeys.METHOD, "xml");
+        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
+        transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
+        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4");
+
+        final StringWriter writer = new StringWriter();
+        transformer.transform(new DOMSource(doc),
+            new StreamResult(writer));
+        LOG.warn(writer.getBuffer().toString());
+    }
+
+    private Document validate(final String resource) throws Exception {
+        final TransactionProvider transactionProvider = initCandidateTransaction();
+        return validate(resource, transactionProvider);
+    }
+
+    private Document validate(final String resource, final TransactionProvider transactionProvider) throws Exception {
+        final Validate validate = new Validate(SESSION_ID_FOR_REPORTING, transactionProvider);
+        return executeOperation(validate, resource);
+    }
+
+    private Document edit(final String resource, final TransactionProvider transactionProvider) throws Exception {
+        final EditConfig editConfig = new EditConfig(SESSION_ID_FOR_REPORTING, currentSchemaContext,
+            transactionProvider);
+        return executeOperation(editConfig, resource);
+    }
+
+    private Document commit(final TransactionProvider transactionProvider) throws Exception {
+        final Commit commit = new Commit(SESSION_ID_FOR_REPORTING, transactionProvider);
+        return executeOperation(commit, "messages/validate/commit.xml");
+    }
+
+    private TransactionProvider initCandidateTransaction() {
+        final TransactionProvider transactionProvider = new TransactionProvider(dataBroker, SESSION_ID_FOR_REPORTING);
+        // Emulate non empty <candidate> DS to make sure validate is not skipped:
+        transactionProvider.getOrCreateTransaction();
+        return transactionProvider;
+    }
+
+    private static Document executeOperation(final NetconfOperation op, final String filename) throws Exception {
+        final Document request = XmlFileLoader.xmlFileToDocument(filename);
+        final Document response = op.handle(request, NetconfOperationChainedExecution.EXECUTION_TERMINATION_POINT);
+
+        LOG.debug("Got response {}", response);
+        return response;
+    }
+}
diff --git a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/WriteTransactionTest.java b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/WriteTransactionTest.java
index d0cbb3235..74313a1ba 100644
--- a/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/WriteTransactionTest.java
+++ b/infra/data-impl/src/test/java/io/fd/honeycomb/data/impl/WriteTransactionTest.java
@@ -119,7 +119,6 @@ public class WriteTransactionTest {
     @Test
     public void testCommit() throws TranslationException {
         writeTx.commit();
-        verify(configSnapshot).validate();
         verify(configSnapshot).commit();
     }
 
diff --git a/infra/data-impl/src/test/resources/messages/rpc-reply_ok.xml b/infra/data-impl/src/test/resources/messages/rpc-reply_ok.xml
new file mode 100644
index 000000000..df205b60b
--- /dev/null
+++ b/infra/data-impl/src/test/resources/messages/rpc-reply_ok.xml
@@ -0,0 +1,19 @@
+<!--
+  ~ Copyright (c) 2018 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.
+  -->
+
+<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="a">
+    <ok/>
+</rpc-reply>
\ No newline at end of file
diff --git a/infra/data-impl/src/test/resources/messages/validate/commit.xml b/infra/data-impl/src/test/resources/messages/validate/commit.xml
new file mode 100644
index 000000000..a4a98f4ca
--- /dev/null
+++ b/infra/data-impl/src/test/resources/messages/validate/commit.xml
@@ -0,0 +1,19 @@
+<!--
+  ~ Copyright (c) 2018 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.
+  -->
+
+<rpc message-id="a" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+    <commit/>
+</rpc>
diff --git a/infra/data-impl/src/test/resources/messages/validate/edit-config-create-top-container.xml b/infra/data-impl/src/test/resources/messages/validate/edit-config-create-top-container.xml
new file mode 100644
index 000000000..b75a4504a
--- /dev/null
+++ b/infra/data-impl/src/test/resources/messages/validate/edit-config-create-top-container.xml
@@ -0,0 +1,28 @@
+<!--
+  ~ Copyright (c) 2018 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.
+  -->
+
+<rpc message-id="a" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+    <edit-config>
+        <target>
+            <candidate/>
+        </target>
+        <config>
+            <top-container xmlns="urn:honeycomb:params:xml:ns:yang:test:validate" xmlns:a="urn:ietf:params:xml:ns:netconf:base:1.0" a:operation="create">
+                <name>top-container-name</name>
+            </top-container>
+        </config>
+    </edit-config>
+</rpc>
\ No newline at end of file
diff --git a/infra/data-impl/src/test/resources/messages/validate/edit-config-missing-mandatory-node.xml b/infra/data-impl/src/test/resources/messages/validate/edit-config-missing-mandatory-node.xml
new file mode 100644
index 000000000..829ef567a
--- /dev/null
+++ b/infra/data-impl/src/test/resources/messages/validate/edit-config-missing-mandatory-node.xml
@@ -0,0 +1,35 @@
+<!--
+  ~ Copyright (c) 2018 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.
+  -->
+
+<rpc message-id="a" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+    <edit-config>
+        <target>
+            <candidate/>
+        </target>
+        <default-operation>none</default-operation>
+        <config>
+            <top-container xmlns="urn:honeycomb:params:xml:ns:yang:test:validate" xmlns:a="urn:ietf:params:xml:ns:netconf:base:1.0" a:operation="create">
+                <list-in-container>
+                    <name>item1</name>>
+                </list-in-container>
+                <list-in-container>
+                    <name>item2</name>
+                    <description>description2</description>
+                </list-in-container>
+            </top-container>
+        </config>
+    </edit-config>
+</rpc>
\ No newline at end of file
diff --git a/infra/data-impl/src/test/resources/messages/validate/validate.xml b/infra/data-impl/src/test/resources/messages/validate/validate.xml
new file mode 100644
index 000000000..3c1ba8c65
--- /dev/null
+++ b/infra/data-impl/src/test/resources/messages/validate/validate.xml
@@ -0,0 +1,23 @@
+<!--
+  ~ Copyright (c) 2018 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.
+  -->
+
+<rpc message-id="a" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
+    <validate>
+        <source>
+            <candidate/>
+        </source>
+    </validate>
+</rpc>
\ No newline at end of file
diff --git a/infra/data-impl/src/test/resources/test-validate.yang b/infra/data-impl/src/test/resources/test-validate.yang
new file mode 100644
index 000000000..144045661
--- /dev/null
+++ b/infra/data-impl/src/test/resources/test-validate.yang
@@ -0,0 +1,27 @@
+module test-validate {
+    yang-version 1;
+    namespace "urn:honeycomb:params:xml:ns:yang:test:validate";
+    prefix "td";
+
+    revision "2018-06-08" {
+        description "Initial revision";
+    }
+
+    container top-container {
+        leaf name {
+            type string;
+        }
+        list list-in-container {
+            key "name";
+
+            leaf name {
+                type string;
+            }
+
+            leaf description {
+                type string;
+                mandatory true;
+            }
+        }
+    }
+}