implement addPriority

Author: mshima

lib/environment.js

@@ -1409,7 +1409,20 @@ class Environment extends Base {
       );
     });
   }
+
+  /**
+   * Add priority
+   * @param {string} priority
+   * @param {string} before
+   */
+  addPriority(priority, before) {
+    if (this.env.runLoop.queueNames.includes(priority)) {
+      return;
+    }
+    this.env.runLoop.addSubQueue(priority, before);
+  }
 }
+
 Object.assign(Environment.prototype, resolver);
 Object.assign(Environment.prototype, composability);
 Object.assign(Environment.prototype, spawnCommandMixin);