Messages are out of order due to behaviour of priorityQueue

lib/clients/client.js

@@ -59,7 +59,7 @@ function BaseAPIClient(token, opts) {
    * @type {Object}
    * @private
    */
-  this.requestQueue = async.priorityQueue(
+  this.requestQueue = async.queue(
     bind(this._callTransport, this),
     clientOpts.maxRequestConcurrency || 3
   );

test/clients/web/client.js

@@ -72,6 +72,37 @@ describe('Web API Client', function () {
     });
   });
 
+  it('should make API calls in the order they are executed', function (done) {
+    var args1 = {
+      headers: {},
+      statusCode: 200,
+      body: '{"test": 10}'
+    };
+
+    var args2 = {
+      headers: {},
+      statusCode: 200,
+      body: '{"test": 20}'
+    };
+
+    var client = new WebAPIClient('test-token', { transport: mockTransport });
+    sinon.spy(client, 'transport');
+
+    client._makeAPICall('test', args1, null, function () {
+      expect(client.transport.callCount).to.equal(1);
+      expect(client.transport.args[0][0].data.body).to.equal('{"test": 10}');
+      expect(client.transport.args.length).to.equal(1);
+    });
+    client._makeAPICall('test', args2, null, function () {
+      expect(client.transport.callCount).to.equal(2);
+      expect(client.transport.args[0][0].data.body).to.equal('{"test": 10}');
+      expect(client.transport.args[1][0].data.body).to.equal('{"test": 20}');
+      expect(client.transport.args.length).to.equal(2);
+
+    });
+    done();
+  });
+
   it('should not crash when no callback is supplied to an API request', function () {
     var client = new WebAPIClient('test-token', { transport: mockTransport });