javascript – 如何在不重复超类测试的情况下测试Mocha中的Backbone子类？

假设我有几个Backbone模型,Rectangle和Triangle,每个都扩展了polygon.

var polygon = Backbone.Model.extend({
    defaults: {
       width: 100,height: 100,rotation: 0
    },rotate: function (degrees) {
       var oldRotation = this.get('rotation');
       var newRotation = (oldRotation + degrees) % 360;
       this.set('rotation',newRotation);
       return newRotation;
    }
});

var Rectangle = polygon.extend({
    area: function (degrees) {
      return this.get('width') * this.get('height');
    }
});

var Triangle = polygon.extend({
    area: function (degrees) {
      return this.get('width') * this.get('height') / 2;
    }
}

我想测试Rectangle和Triangle并确保它们中的每一个都独立地实现正确旋转,即使我知道(现在)它们都从polygon继承了rotate的实现.

我不想做的是为Rectangle和Triangle创建单独的单元测试,它们几乎完全相互重复.在Mocha中,我如何编写旋转测试并在三角形和矩形的单元测试中重用它？

这是我的单元测试.请注意副本’旋转45度’测试.

describe('A rectangle',function () {
  var r = new Rectangle({width: 50,height: 10,rotation: 90});
  it('correctly calculates its area',function () {
    expect(r.area()).to.equal(500);
  });
  it('rotates by 45 degrees',function () {
    expect(r.rotate(45)).to.equal(135);
  });
});

describe('A triangle',function () {
  var t = new Triangle({width: 50,function () {
    expect(t.area()).to.equal(250);
  });
  it('rotates by 45 degrees',function () {
    expect(t.rotate(45)).to.equal(135);
  });
});

解决方法

写完后答案很明显.我们可以创建一个函数来封装多边形的测试.

var describeApolygon = function (name,p) {
    describe(name,function () {        
      it('rotates by 45 degrees',function () {
        expect(p.rotate(45)).to.equal(135);
      });
    });
};

然后在Rectangle和Triangle的测试中使用它.

describe('A rectangle',function () {
    var r = new Rectangle({width: 50,rotation: 90});
    describeApolygon('A rectangle',r);
    it('correctly calculates its area',function () {
      expect(r.area()).to.equal(500);
    });
});


describe('A triangle',function () {
    var t = new Triangle({width: 50,rotation: 90});
    describeApolygon('A triangle',t);
    it('correctly calculates its area',function () {
      expect(t.area()).to.equal(250);
    });
});

这是我能找到的最干净的解决方案.我很好奇是否有其他人已经解决了这个问题,并想出了一些不同的东西.