add queue tests for job creation

test/fixtures/worker.js

@@ -0,0 +1,16 @@
+import events from 'events';
+
+export default class Worker extends events.EventEmitter {
+  constructor(queue, type, workerFn, opts = {}) {
+    super();
+
+    this.queue = queue;
+    this.type = type;
+    this.workerFn = workerFn;
+    this.options = opts;
+  }
+
+  getProp(name) {
+    return this[name];
+  }
+}