Improve rpc result validation

web3.js/src/connection.js

@@ -58,95 +58,76 @@ const GetBalanceRpcResult = struct({
 });
 
 
+/**
+ * @private
+ */
+function jsonRpcResult(resultDescription: any) {
+  const jsonRpcVersion = struct.literal('2.0');
+  return struct.union([
+    struct({
+      jsonrpc: jsonRpcVersion,
+      id: 'string',
+      error: 'any'
+    }),
+    struct({
+      jsonrpc: jsonRpcVersion,
+      id: 'string',
+      error: 'null?',
+      result: resultDescription,
+    }),
+  ]);
+}
+
+
 /**
  * Expected JSON RPC response for the "getAccountInfo" message
  */
-const GetAccountInfoRpcResult = struct({
+const GetAccountInfoRpcResult = jsonRpcResult({
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: struct.optional({
   program_id: 'array',
   tokens: 'number',
   userdata: 'array',
-  }),
 });
 
 
 /**
  * Expected JSON RPC response for the "confirmTransaction" message
  */
-const ConfirmTransactionRpcResult = struct({
+const ConfirmTransactionRpcResult = jsonRpcResult('boolean');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'boolean?',
-});
 
 /**
  * Expected JSON RPC response for the "getSignatureStatus" message
  */
-const GetSignatureStatusRpcResult = struct({
+const GetSignatureStatusRpcResult = jsonRpcResult(struct.enum([
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: struct.optional(struct.enum([
   'Confirmed',
   'SignatureNotFound',
   'ProgramRuntimeError',
   'GenericFailure',
-  ])),
+]));
-});
 
 /**
  * Expected JSON RPC response for the "getTransactionCount" message
  */
-const GetTransactionCountRpcResult = struct({
+const GetTransactionCountRpcResult = jsonRpcResult('number');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'number?',
-});
 
 /**
  * Expected JSON RPC response for the "getLastId" message
  */
-const GetLastId = struct({
+const GetLastId = jsonRpcResult('string');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'string?',
-});
 
 /**
  * Expected JSON RPC response for the "getFinality" message
  */
-const GetFinalityRpcResult = struct({
+const GetFinalityRpcResult = jsonRpcResult('number');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'number?',
-});
 
 /**
  * Expected JSON RPC response for the "requestAirdrop" message
  */
-const RequestAirdropRpcResult = struct({
+const RequestAirdropRpcResult = jsonRpcResult('string');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'string?',
-});
 
 /**
  * Expected JSON RPC response for the "sendTransaction" message
  */
-const SendTokensRpcResult = struct({
+const SendTokensRpcResult = jsonRpcResult('string');
-  jsonrpc: struct.literal('2.0'),
-  id: 'string',
-  error: 'any?',
-  result: 'string?',
-});
 
 /**
  * Information describing an account

web3.js/test/connection.test.js

@@ -5,9 +5,9 @@ import {Connection} from '../src/connection';
 import {SystemProgram} from '../src/system-program';
 import {mockRpc} from './__mocks__/node-fetch';
 
-let url = 'http://testnet.solana.com:8899';
+let url = 'http://localhost:8899';
+//url = 'http://testnet.solana.com:8899';
 //url = 'http://master.testnet.solana.com:8899';
-//url = 'http://localhost:8899';
 
 const errorMessage = 'Invalid request';
 const errorResponse = {