Javascript 测试框架之 隐式声明 之 describe

为什么使用 javascript 测试框架时，没有显式导入 describe，却可以直接使用：？

https://*.com/questions/12209582/the-describe-keyword-in-javascript

问题：
So I am a newbie in javascript and i had been going through some one else's code and I found this..
我是 javascript  的新手，我遇到了别人写的代码如下：

describe('deviceready', function() {
    it('should report that it fired', function() {
        spyOn(app, 'report');
        app.deviceready();
        expect(app.report).toHaveBeenCalledWith('deviceready');
    });
});

What I don't understand is: What exactly does the describe keyword do?
我不明白的是：describe 关键字到底做了什么？


回答：
Describe is a function in the Jasmine testing framework. It simply describes the suite of test cases enumerated by the "it" functions.
Describe 是 Jasmine 测试框架的一个函数。它只是描述了一组用 it 函数枚举的测试用例。

Also used in the mochajs framework.
Describe 也被用在了 mochajs 测试框架中。



Describe is not part of Javascript, it is a function defined in the library you used (namely Jasmine)
Describe 不属于原生 Javascript 的一部分，它是定义在 Jasmine 框架的类库中。

http://jasmine.github.io/


--------------------------------------

引用

"A test suite begins with a call to the global Jasmine function describe with two parameters: a string and a function. The string is a name or title for a spec suite - usually what is being tested. The function is a block of code that implements the suite."

来源:
http://jasmine.github.io/2.0/introduction.html

-------------------------------------------------------


https://www.bignerdranch.com/blog/why-do-javascript-test-frameworks-use-describe-and-beforeeach/


-------------------------------------------------------
原理：

Nodejs Global Functions

https://*.com/questions/29544417/nodejs-global-functions

我有一个非常基础的函数，在 functions.js 文件中：

// functions.js
function echo(input){
    process.stdout.write(echo);
}

我在另一个文件中使用它：

// another_file.js
echo("hello!");

然后在 mainFile 文件中运行：

// main_file.js
require("functions.js");
require("another_file.js");

结果出错了：

ReferenceError: echo is not defined

Is there a way for me to make a function that is global like that without havingin to use exports?

有没有一个方法，可以不使用 exports 关键字，而使这个函数可以全局访问？


回答：

Inside functions.js you'll have access to node's global variable, which is like the window variable in a browser. As Plato suggested in a comment, you can add this to the global by simply doing echo = function echo(input){ ... }. However, this will throw an error if you're using strict mode, which is intended to catch common mistakes (like accidentally creating global variables).

在 functions.js 文件中，你可以访问 nodejs 的全局变量 global，
这跟浏览器里面的 window 变量差不多。

像 Plato 建议的是，你可以将它添加到 gobal 中，通过以下方法：

echo = function echo(input){ 
   process.stdout.write(echo);
};

// 注意：echo 变量前，没有任何修饰符。

但是，如果在 strict 模式下，这会报错。

-------------------------------------------------

One way to safely add echo as a global is to add it to the global global variable.
一个安全的方法是把 echo 添加到 global 变量中：

"use strict";

global.echo = function echo(input) {
    process.stdout.write(input);
}

https://*.com/questions/29544417/nodejs-global-functions

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