[PAN-2705] helpful graphql error when an account doesn't exist (#1460)

When we are asking for an account at an address that does not exist the
error message should state that the account doesn't exist.
Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

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

@@ -12,7 +12,10 @@
  */
 package tech.pegasys.pantheon.ethereum.graphqlrpc;
 
+import static com.google.common.base.Preconditions.checkArgument;
+
 import tech.pegasys.pantheon.ethereum.blockcreation.MiningCoordinator;
+import tech.pegasys.pantheon.ethereum.core.Account;
 import tech.pegasys.pantheon.ethereum.core.Address;
 import tech.pegasys.pantheon.ethereum.core.Hash;
 import tech.pegasys.pantheon.ethereum.core.SyncStatus;
@@ -163,7 +166,9 @@ public class GraphQLDataFetchers {
       if (bn != null) {
         final Optional<WorldState> ws = blockchainQuery.getWorldState(bn);
         if (ws.isPresent()) {
-          return Optional.of(new AccountAdapter(ws.get().get(addr)));
+          final Account account = ws.get().get(addr);
+          checkArgument(account != null, "Account with address %s does not exist", addr);
+          return Optional.of(new AccountAdapter(account));
         } else if (bn > blockchainQuery.getBlockchain().getChainHeadBlockNumber()) {
           // block is past chainhead
           throw new GraphQLRpcException(GraphQLRpcError.INVALID_PARAMS);
@@ -171,11 +176,18 @@ public class GraphQLDataFetchers {
           // we don't have that block
           throw new GraphQLRpcException(GraphQLRpcError.CHAIN_HEAD_WORLD_STATE_NOT_AVAILABLE);
         }
+      } else {
+        // return account on latest block
+        final long latestBn = blockchainQuery.latestBlock().get().getHeader().getNumber();
+        final Optional<WorldState> ows = blockchainQuery.getWorldState(latestBn);
+        return ows.flatMap(
+                ws -> {
+                  Account account = ws.get(addr);
+                  checkArgument(account != null, "Account with address %s does not exist", addr);
+                  return Optional.ofNullable(account);
+                })
+            .map(AccountAdapter::new);
       }
-      // return account on latest block
-      final long latestBn = blockchainQuery.latestBlock().get().getHeader().getNumber();
-      final Optional<WorldState> ows = blockchainQuery.getWorldState(latestBn);
-      return ows.flatMap(ws -> Optional.ofNullable(ws.get(addr))).map(AccountAdapter::new);
     };
   }
 

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

@@ -72,6 +72,8 @@ public class EthGraphQLRpcHttpBySpecTest extends AbstractEthGraphQLRpcHttpServic
     specs.add("eth_call_BlockLatest");
     specs.add("eth_getBalance_latest");
     specs.add("eth_getBalance_0x19");
+    specs.add("eth_getBalance_invalidAccountBlockNumber");
+    specs.add("eth_getBalance_invalidAccountLatest");
     specs.add("eth_gasPrice");
 
     specs.add("eth_getTransactionReceipt");

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

@@ -0,0 +1,22 @@
+{
+  "request": "{account(blockNumber:\"0x19\", address: \"0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef\") { balance } }",
+  "response": {
+    "data": null,
+    "errors": [
+      {
+        "message": "Exception while fetching data (/account) : Account with address 0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef does not exist",
+        "locations": [
+          {
+            "line": 1,
+            "column": 2
+          }
+        ],
+        "path": [
+          "account"
+        ]
+      }
+    ]
+  },
+  "statusCode": 400
+}
+

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

@@ -0,0 +1,22 @@
+{
+  "request": "{account(address: \"0xdeaff00ddeaff00ddeaff00ddeaff00ddeaff00d\") { balance } }",
+  "response": {
+    "data": null,
+    "errors": [
+      {
+        "message": "Exception while fetching data (/account) : Account with address 0xdeaff00ddeaff00ddeaff00ddeaff00ddeaff00d does not exist",
+        "locations": [
+          {
+            "line": 1,
+            "column": 2
+          }
+        ],
+        "path": [
+          "account"
+        ]
+      }
+    ]
+  },
+  "statusCode": 400
+}
+