fix: wait for the next lastId before sending a new transaction

web3.js/test/connection.test.js

@@ -6,6 +6,7 @@ import {
   SystemProgram,
 } from '../src';
 import {mockRpc, mockRpcEnabled} from './__mocks__/node-fetch';
+import {mockGetLastId} from './mockrpc/getlastid';
 import {url} from './url';
 
 if (!mockRpcEnabled) {
@@ -117,18 +118,7 @@ test('get transaction count', async () => {
 test('get last Id', async () => {
   const connection = new Connection(url);
 
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]
-  );
+  mockGetLastId();
 
   const lastId = await connection.getLastId();
   expect(lastId.length).toBeGreaterThanOrEqual(43);
@@ -283,18 +273,7 @@ test('transaction', async () => {
   await connection.requestAirdrop(accountTo.publicKey, 21);
   expect(await connection.getBalance(accountTo.publicKey)).toBe(21);
 
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]
-  );
+  mockGetLastId();
   mockRpc.push([
     url,
     {

web3.js/test/mockrpc/getlastid.js

@@ -0,0 +1,23 @@
+// @flow
+
+import {
+  Account,
+} from '../../src';
+import {url} from '../url';
+import {mockRpc} from '../__mocks__/node-fetch';
+
+export function mockGetLastId() {
+  const lastId = new Account();
+
+  mockRpc.push([
+    url,
+    {
+      method: 'getLastId',
+      params: [],
+    },
+    {
+      error: null,
+      result: lastId.publicKey.toBase58(),
+    }
+  ]);
+}

web3.js/test/token-program.test.js

@@ -10,26 +10,13 @@ import {SYSTEM_TOKEN_PROGRAM_ID} from '../src/token-program';
 import {mockRpc, mockRpcEnabled} from './__mocks__/node-fetch';
 import {url} from './url';
 import {newAccountWithTokens} from './new-account-with-tokens';
+import {mockGetLastId} from './mockrpc/getlastid';
 
 if (!mockRpcEnabled) {
   // The default of 5 seconds is too slow for live testing sometimes
   jest.setTimeout(10000);
 }
 
-function mockGetLastId() {
-  mockRpc.push([
-    url,
-    {
-      method: 'getLastId',
-      params: [],
-    },
-    {
-      error: null,
-      result: '2BjEqiiT43J6XskiHdz7aoocjPeWkCPiKD72SiFQsrA2',
-    }
-  ]);
-}
-
 function mockGetSignatureStatus(result: string = 'Confirmed') {
   mockRpc.push([
     url,