javascript jasmin：类的模拟实例
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jasmin: mock instance of a class
提问by Andrew
Is it possible to create a mock of an object objsuch that Jasmine test like
是否可以创建一个对象obj的模拟，这样 Jasmine 测试就像
expect(fakeB instanceof B).toBe(true);
passes?
通过？
In other words, I have a class Awith a method convertToBwhich argument must be an instance of a class B:
换句话说，我有一个带有方法convertToB的类A，该方法的参数必须是类B的实例：
function A(){
this.convertToB = function(elem){
if (!(elem instanceof B)){ throw an error}
...
...
}
}
I would like to cover with test that piece of code by creating a mock object that when being asked whether it is an instance of Bwould respond true.
我想通过创建一个模拟对象来测试那段代码，当被问及它是否是B的实例时，它会响应true。
For the moment I am forced to write tests kind of
目前我被迫编写测试
- it('throws an error if the argument is a string')
- it('throws an error if the argument is an array')
- ...
- it('如果参数是字符串则抛出错误')
- it('如果参数是数组则抛出错误')
- ...
which is a bit annoying. I expect a command like
这有点烦人。我期待像这样的命令
var fakeB = jasmine.createFake('B')
so that the first line of code in this question would pass.
这样问题中的第一行代码就会通过。
回答by Wojciech Szela
I have dozens of places in my code exactly as yours. spyOn method of Jasmine 2.0 will do the job. Same with Jasmine 1.0 but I don't remember if the method is called/used exactly the same way. To the example:
我的代码中有几十个地方和你的完全一样。Jasmine 2.0 的 spyOn 方法将完成这项工作。与 Jasmine 1.0 相同，但我不记得该方法的调用/使用方式是否完全相同。举个例子：
var realB = new B();
// change realB instance into a spy and mock its method 'foo' behaviour to always return 'bar'
// it will still respond "true" to "realB instanceof B"
spyOn(realB, 'foo').and.returnValue('bar')
var realC = new C();
// C.baz is expecting instance of B to be passed as first argument
var result = C.baz(realB)
// assuming C.baz return realB.foo() concatenated with '123'
expect(result).toEqual('bar123');
Jasmine documentation has extensive list of examples of spies: http://jasmine.github.io/2.0/introduction.html
Jasmine 文档包含大量间谍示例列表：http: //jasmine.github.io/2.0/introduction.html
回答by g13013
My implementation is as follows:
我的实现如下：
function proxyConstructor(obj) {
obj = obj || {};
for (var key in obj) {
this[key] = obj[key];
}
this.prop = 'runtime prop';
this.instanceMethod(1);
}
var TestClass = jasmine.createSpy(`TestClass.constructor`).and.callFake(proxyConstructor);
TestClass.prototype.instanceMethod = jasmine.createSpy(`TestClass#instanceMethod`);
TestClass.staticMethod = jasmine.createSpy(`TestClass.staticMethod`);
var ins = new TextClass();
expect(ins).toBe(jasmine.any(TestClass)) // success
expect(ins.prop).toBe('runtime prop'); // success
expect(ins.instanceMethod.toHaveBeenCalledWith(1)) // success