ChaiJS期望构造函数抛出错误

Question

我试图测试我的构造函数将使用Teaspoon gem为Rails抛出错误,ChaiJS作为我的断言库.

当我运行以下测试时:

  it('does not create the seat if x < 0', function() {
    var badConstructor = function() {
      return new Seat({ radius: 10, x: -0.1, y: 0.2, seat_number: 20, table_number: 30});
    };

    expect(badConstructor).to.throw(Error, 'Invalid location');
  });

我得到这个输出:

失败:

  1) Seat does not create the seat if x < 0
     Failure/Error: undefined is not a constructor (evaluating 'expect(badConstructor).to.throw(Error(), 'Invalid location')')

构造函数抛出错误,但我认为我没有正确编写测试.

当我尝试运行expect(badConstructor())然后我得到输出:

Failures:

  1) Seat does not create the seat if x < 0
     Failure/Error: Invalid location

Answer 1

有同样的问题.用函数包装你的构造函数:

var fcn = function(){new badConstructor()};
expect(fcn).to.throw(Error, 'Invalid location');

Answer 2

要测试构造函数内的抛出消息错误，可以使用 mocha 和 chai 编写此测试（使用 ES6 语法）：

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\'use strict\';\n// ES6 class definition\nclass A {\n  constructor(msg) {\n    if(!msg) throw new Error(\'Give me the message\');\n    this.message = msg;\n  }\n}\n\n// test.js\ndescribe(\'A constructor\', function() {\n  it(\'Should throw an error with "Give me the message" text if msg is null\', function() {\n    (() => new A()).should.throw(Error, /Give me the message/);\n  });\n});\n

\n\n请参阅此笔，检查CodePen上的 Diego A. Zapata H\xc3\xa4ntsch ( @diegoazh )对上述代码zJppaj的实时运行情况。

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