PAN-2711 - Don't require 'to' in 'blocks' queries (#1464)

{blocks(from:7777777) {number}} should work, instead it is requiring a to: argument when it should be implied as latest
Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

ethereum/graphqlrpc/src/main/java/tech/pegasys/pantheon/ethereum/graphqlrpc/GraphQLDataFetchers.java

@@ -115,19 +115,24 @@ public class GraphQLDataFetchers {
   DataFetcher<List<NormalBlockAdapter>> getRangeBlockDataFetcher() {
 
     return dataFetchingEnvironment -> {
+      final BlockchainQuery blockchainQuery =
+          ((GraphQLDataFetcherContext) dataFetchingEnvironment.getContext()).getBlockchainQuery();
+
       final long from = dataFetchingEnvironment.getArgument("from");
-      final long to = dataFetchingEnvironment.getArgument("to");
+      final long to;
+      if (dataFetchingEnvironment.containsArgument("to")) {
+        to = dataFetchingEnvironment.getArgument("to");
+      } else {
+        to = blockchainQuery.latestBlock().map(block -> block.getHeader().getNumber()).orElse(0L);
+      }
       if (from > to) {
         throw new GraphQLRpcException(GraphQLRpcError.INVALID_PARAMS);
       }
 
-      final BlockchainQuery blockchain =
-          ((GraphQLDataFetcherContext) dataFetchingEnvironment.getContext()).getBlockchainQuery();
-
       final List<NormalBlockAdapter> results = new ArrayList<>();
       for (long i = from; i <= to; i++) {
         final Optional<BlockWithMetadata<TransactionWithMetadata, Hash>> block =
-            blockchain.blockByNumber(i);
+            blockchainQuery.blockByNumber(i);
         block.ifPresent(e -> results.add(new NormalBlockAdapter(e)));
       }
       return results;

ethereum/graphqlrpc/src/test/java/tech/pegasys/pantheon/ethereum/graphqlrpc/EthGraphQLRpcHttpBySpecTest.java

@@ -87,6 +87,7 @@ public class EthGraphQLRpcHttpBySpecTest extends AbstractEthGraphQLRpcHttpServic
 
     specs.add("eth_getLogs_matchTopic");
 
+    specs.add("graphql_blocks_noTo");
     specs.add("graphql_pending");
     return specs;
   }
@@ -108,14 +109,14 @@ public class EthGraphQLRpcHttpBySpecTest extends AbstractEthGraphQLRpcHttpServic
 
     importBlocks(1, BLOCKS.size());
     try (final Response resp = client.newCall(request).execute()) {
-      final int expectedStatusCode = spec.getInteger("statusCode");
-      assertThat(resp.code()).isEqualTo(expectedStatusCode);
-
       final JsonObject expectedRespBody = spec.getJsonObject("response");
       final String resultStr = resp.body().string();
 
       final JsonObject result = new JsonObject(resultStr);
       assertThat(result).isEqualTo(expectedRespBody);
+
+      final int expectedStatusCode = spec.getInteger("statusCode");
+      assertThat(resp.code()).isEqualTo(expectedStatusCode);
     }
   }
 

ethereum/graphqlrpc/src/test/resources/tech/pegasys/pantheon/ethereum/graphqlrpc/graphql_blocks_noTo.json

@@ -0,0 +1,19 @@
+{
+  "request": "{ blocks(from:30) { number } }",
+  "response": {
+    "data": {
+      "blocks": [
+        {
+          "number": 30
+        },
+        {
+          "number": 31
+        },
+        {
+          "number": 32
+        }
+      ]
+    }
+  },
+  "statusCode": 200
+}