Javascript 茉莉花-如何测试错误？

情况：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

大家好。我正在学习jasmine来测试我的angular应用程序

我已经创建了一个基本函数，它将两个数相乘。 如果给定的参数不是数字，函数将抛出错误

然后我做了两个非常基本的测试

首先检查函数是否正确地将数字相乘。 第二种方法是检查如果字符串作为参数给出，函数是否正确抛出错误

第一次测试通过，第二次不通过。我不明白为什么

代码：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

功能：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

规范：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

输出：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

如果我理解正确的话，茉莉。这两个测试都应该通过，因为在第二种情况下，函数会像我们预期的那样抛出错误

问题：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

如何测试函数是否正确抛出错误

编辑：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

我正在尝试此新代码，但仍然不起作用：

describe('The function', function () 
{

    it('throw an error if a parameter is not a number', function () 
    {

        expect(function() { Multiply(10, 'aaaa') }).toThrowError(new Error("not a number"));

    });

});

输出：

function Multiply( num1, num2 )
{

    var result;

    if (isNaN(num1) || isNaN(num2)) 
    {
        throw new Error("not a number");
    }
    else
    {
        result = num1 * num2;

        return result;
    }

}

describe('The function', function () 
{
    it('properly multiply two numbers', function () 
    {
        result = Multiply(10, 5);
        expect(result).toEqual(50);
    });

    it('throw an error if a parameter is not a number', function () 
    {
        result = Multiply(10, 'aaaa');

        expect(result).toThrow(new Error("not a number"));

    });

});

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: not a number
Error: not a number
    at Multiply (http://localhost/jasmine_test/src/app.js:8:9)

2 specs, 1 failure
Spec List | Failures
The function throw an error if a parameter is not a number
Error: Expected is not an Error, string, or RegExp.

---

如果我理解正确，您需要将函数传递到

expect（…）

调用中

您在此处拥有的代码：

expect(result).toThrow(new Error("not a number"));

正在检查乘法的结果，当它工作时，这是正常的，但正如我所说的。toThrow（）需要一个函数，我将使用匿名函数，请参见以下内容：

expect( function(){ Multiply(10, 'aaaa'); } ).toThrow(new Error("not a number"));

---

编辑：进行了快速搜索，博客文章对我想说的内容进行了非常详细的解释。

您需要将您希望在函数中抛出错误的代码放入：

expect(function () {
    Multiply(10, 'aaaa');
}).toThrow(Error, 'not a number');

否则，当您运行断言时，错误已经抛出范围之外。您可以在

• 对于方法内部处理的异常，上述方法完全正确
• 当您必须测试服务时，您可以使用模拟机制进行测试
• 使用NgModule providers部分的优势创建模拟

• 在descripe（）块中

providers:[{provide:APIService，useValue:{api:{filterTaskDetails:（）=>throwError（'Error'）}]

要从

rxjs

导入的

throwerr

• 在expect（）中，将其块测试为

spyOn（组件['toaster']，'showError'）；
/**添加（）块**/
预期（组件['toaster'].淋浴器）已提前（1）；

您需要在作为“expect”参数传递的匿名函数中运行它

expect（function（）{Multiply（10，'aaaa'）}）

-否则jasmine没有机会捕获它，您需要

。tothrower（错误，“不是数字”）

。更新了我的答案。也可以使用这个

expect（（）=>{Multiply（10，'aaaa'）；}）