Initial implementation of ibft_getValidatorsByBlockNumber (#499)

* Initial implementation of ibft_getValidatorsByBlockHash
* Added in missing method to blockchain queries and cleaned up code.

consensus/ibft/src/main/java/tech/pegasys/pantheon/consensus/ibft/jsonrpc/IbftJsonRpcMethodsFactory.java

@@ -12,13 +12,16 @@
  */
 package tech.pegasys.pantheon.consensus.ibft.jsonrpc;
 
+import tech.pegasys.pantheon.consensus.ibft.IbftBlockInterface;
 import tech.pegasys.pantheon.consensus.ibft.IbftContext;
 import tech.pegasys.pantheon.consensus.ibft.jsonrpc.methods.IbftDiscardValidatorVote;
+import tech.pegasys.pantheon.consensus.ibft.jsonrpc.methods.IbftGetValidatorsByBlockNumber;
 import tech.pegasys.pantheon.consensus.ibft.jsonrpc.methods.IbftProposeValidatorVote;
 import tech.pegasys.pantheon.ethereum.ProtocolContext;
 import tech.pegasys.pantheon.ethereum.jsonrpc.RpcApi;
 import tech.pegasys.pantheon.ethereum.jsonrpc.internal.methods.JsonRpcMethod;
 import tech.pegasys.pantheon.ethereum.jsonrpc.internal.parameters.JsonRpcParameter;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.queries.BlockchainQueries;
 
 import java.util.Collection;
 import java.util.HashMap;
@@ -34,10 +37,14 @@ public class IbftJsonRpcMethodsFactory {
     final Map<String, JsonRpcMethod> rpcMethods = new HashMap<>();
 
     if (jsonRpcApis.contains(IbftRpcApis.IBFT)) {
+      BlockchainQueries blockchainQueries =
+          new BlockchainQueries(context.getBlockchain(), context.getWorldStateArchive());
       addMethods(
           rpcMethods,
           new IbftProposeValidatorVote(
               context.getConsensusState().getVoteProposer(), jsonRpcParameter),
+          new IbftGetValidatorsByBlockNumber(
+              blockchainQueries, new IbftBlockInterface(), jsonRpcParameter),
           new IbftDiscardValidatorVote(
               context.getConsensusState().getVoteProposer(), jsonRpcParameter));
     }

consensus/ibft/src/main/java/tech/pegasys/pantheon/consensus/ibft/jsonrpc/methods/IbftGetValidatorsByBlockNumber.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2019 ConsenSys AG.
+ *
+ * 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 tech.pegasys.pantheon.consensus.ibft.jsonrpc.methods;
+
+import tech.pegasys.pantheon.consensus.ibft.IbftBlockInterface;
+import tech.pegasys.pantheon.ethereum.core.BlockHeader;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.JsonRpcRequest;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.methods.AbstractBlockParameterMethod;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.methods.JsonRpcMethod;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.parameters.BlockParameter;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.parameters.JsonRpcParameter;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.queries.BlockchainQueries;
+
+import java.util.Optional;
+
+public class IbftGetValidatorsByBlockNumber extends AbstractBlockParameterMethod
+    implements JsonRpcMethod {
+
+  private final IbftBlockInterface ibftBlockInterface;
+
+  public IbftGetValidatorsByBlockNumber(
+      final BlockchainQueries blockchainQueries,
+      final IbftBlockInterface ibftBlockInterface,
+      final JsonRpcParameter parameters) {
+    super(blockchainQueries, parameters);
+    this.ibftBlockInterface = ibftBlockInterface;
+  }
+
+  @Override
+  protected BlockParameter blockParameter(final JsonRpcRequest request) {
+    return parameters().required(request.getParams(), 0, BlockParameter.class);
+  }
+
+  @Override
+  protected Object resultByBlockNumber(final JsonRpcRequest request, final long blockNumber) {
+    final Optional<BlockHeader> blockHeader =
+        blockchainQueries().getBlockHeaderByNumber(blockNumber);
+    return blockHeader.map(header -> ibftBlockInterface.validatorsInBlock(header)).orElse(null);
+  }
+
+  @Override
+  public String getName() {
+    return "ibft_getValidatorsByBlockNumber";
+  }
+}

consensus/ibft/src/test/java/tech/pegasys/pantheon/consensus/ibft/jsonrpc/methods/IbftGetValidatorsByBlockNumberTest.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2019 ConsenSys AG.
+ *
+ * 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 tech.pegasys.pantheon.consensus.ibft.jsonrpc.methods;
+
+import static org.mockito.Mockito.when;
+
+import tech.pegasys.pantheon.consensus.ibft.IbftBlockInterface;
+import tech.pegasys.pantheon.ethereum.core.Address;
+import tech.pegasys.pantheon.ethereum.core.BlockHeader;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.JsonRpcRequest;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.parameters.BlockParameter;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.parameters.JsonRpcParameter;
+import tech.pegasys.pantheon.ethereum.jsonrpc.internal.queries.BlockchainQueries;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class IbftGetValidatorsByBlockNumberTest {
+
+  @Mock private BlockchainQueries blockchainQueries;
+  @Mock private BlockHeader blockHeader;
+  @Mock private IbftBlockInterface ibftBlockInterface;
+  @Mock private JsonRpcRequest request;
+
+  private final JsonRpcParameter parameters = new JsonRpcParameter();
+  private IbftGetValidatorsByBlockNumber method;
+
+  @Before
+  public void setUp() {
+    method = new IbftGetValidatorsByBlockNumber(blockchainQueries, ibftBlockInterface, parameters);
+  }
+
+  @Test
+  public void blockParameterIsParameter0() {
+    request = new JsonRpcRequest("?", "ignore", new String[] {"0x1245"});
+    BlockParameter blockParameter = method.blockParameter(request);
+    Assertions.assertThat(blockParameter.getNumber().getAsLong()).isEqualTo(0x1245);
+  }
+
+  @Test
+  public void nameShouldBeCorrect() {
+    Assertions.assertThat(method.getName()).isEqualTo("ibft_getValidatorsByBlockNumber");
+  }
+
+  @Test
+  public void shouldReturnListOfValidatorsFromBlock() {
+    when(blockchainQueries.getBlockHeaderByNumber(12)).thenReturn(Optional.of(blockHeader));
+    final List<Address> addresses = Collections.singletonList(Address.ID);
+    when(ibftBlockInterface.validatorsInBlock(blockHeader)).thenReturn(addresses);
+    Object result = method.resultByBlockNumber(request, 12);
+    Assertions.assertThat(result).isEqualTo(addresses);
+  }
+}

ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AbstractBlockParameterMethod.java

@@ -21,7 +21,7 @@ import tech.pegasys.pantheon.ethereum.jsonrpc.internal.response.JsonRpcSuccessRe
 
 import java.util.OptionalLong;
 
-abstract class AbstractBlockParameterMethod implements JsonRpcMethod {
+public abstract class AbstractBlockParameterMethod implements JsonRpcMethod {
 
   private final BlockchainQueries blockchainQueries;
   private final JsonRpcParameter parameters;

ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/queries/BlockchainQueries.java

@@ -370,6 +370,10 @@ public class BlockchainQueries {
     return blockchain.getBlockHashByNumber(blockNumber).flatMap(this::blockByHashWithTxHashes);
   }
 
+  public Optional<BlockHeader> getBlockHeaderByNumber(final long number) {
+    return blockchain.getBlockHeader(number);
+  }
+
   /**
    * Returns the latest block with metadata and a list of transaction hashes rather than full
    * transactions.