Some bits for ReactJS-based client.

test/e2e/lib/worker-counter.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const Promise = require('bluebird');
+
+class WorkerCounter {
+    constructor() {
+        this.counter = 0;
+    }
+
+    enter() {
+        this.counter++;
+    }
+
+    exit() {
+        this.counter--;
+    }
+
+    async waitForEmpty() {
+        const self = this;
+
+        function wait(resolve) {
+            if (self.counter == 0) {
+                resolve();
+            } else {
+                setTimeout(wait, 500, resolve);
+            }
+        }
+
+        return new Promise(resolve => {
+            setTimeout(wait, 500, resolve);
+        })
+    }
+}
+
+module.exports = WorkerCounter;