JEST：我如何为Promise中的函数编写单元测试？

Question

我有一个React商店，代码结构很简单：

    get: function() {
       var getA = new Promise( (resolve, reject) => {
           RestApi.post(url, data, re => resolve(re), re=>reject(re)); // this makes an ajax calls to the rest api
       } );
       var getB = new Promise( (resolve, reject) => {
           RestApi.post(url, data, re => resolve(re), re=>reject(re));
       } );
       var getC = new Promise( (resolve, reject) => {
           RestApi.post(url, data, re => resolve(re), re=>reject(re)); 
       } );

       Promise.all( getA, getB, getC ).then( values => {
           this.set(values);
      } ); 
   },
   set: function(value){
      // code to set the store.
   }

所以我正在尝试使用JEST为这段代码添加单元测试，但是我完全迷失了JEST / Jasmine如何使用promise，以及如何在promise中测试ajax？