How to check if a Promise is pending [duplicate]

You can attach a then handler that sets a done flag on the promise (or the RunTest instance if you prefer), and test that:

     if (!this.promise) {
         this.promise = this.someTest();
         this.promise.catch(() => {}).then(() => { this.promise.done = true; });
         retVal = true;                
     }

     if ( this.promise.done ) {
         this.promise = this.someTest();
         this.promise.catch(() => {}).then(() => { this.promise.done = true; });
         retVal = true;
     }

Notice the empty catch() handler, it’s crucial in order to have the handler called regardless of the outcome of the promise.
You probably want to wrap that in a function though to keep the code DRY.