[英]How to stub a constructor from an imported ES6 module?
I would like to stub the constructor of a class within a test file.我想在测试文件中存根类的构造函数。 Say I have the following:
说我有以下内容:
// Foo.js
export class Foo {}
and和
// myTestFile.js
import {Foo} from "./Foo.js";
import {functionThatUsesFoo} from "./functionThatUsesFoo.js";
class ReplacedFoo {}
// do something to replace `Foo` with `ReplacedFoo` here...
functionThatUsesFoo();
Is there some magic Object.setPrototypeOf()
or Foo.prototype = ReplacedFoo
sort of call that I can do to make sure functionThatUsesFoo()
uses my stubbed constructor.是否有一些神奇的
Object.setPrototypeOf()
或Foo.prototype = ReplacedFoo
之类的调用,我可以确保functionThatUsesFoo()
使用我的存根构造函数。 I'd prefer not to resort to dependency injection.我不想诉诸依赖注入。
Most resources I found about this topic were using nodejs require()
and a testing library that uses node:vm internally.我发现的关于这个主题的大多数资源都在使用 nodejs
require()
和一个在内部使用 node:vm 的测试库。 But I'm using Deno/browser environments where this is not easily available.但我正在使用不易获得的 Deno/浏览器环境。
Some things I tried:我尝试过的一些事情:
Foo.constructor = ReplacedFoo.constructor
Foo.prototype.constructor = ReplacedFoo.prototype.constructor
Foo.prototype = ReplacedFoo.prototype
Foo.prototype = ReplacedFoo
Object.setPrototypeOf(Foo, ReplacedFoo.prototype)
I made a library to solve situations like these that allows you to replace the contents of imported files.我制作了一个库来解决此类情况,允许您替换导入文件的内容。 But it has some inevitable limitations so I want to avoid it where possible.
但它有一些不可避免的限制,所以我想尽可能避免它。 Similarly, using import maps to solve this isn't really a satisfying solution either as it doesn't scale well and I might as well use the library at that point.
同样,使用导入映射来解决这个问题也不是一个真正令人满意的解决方案,因为它不能很好地扩展,我还不如在那时使用该库。
with .mjs you basically want to re-work your code to dependency injections everywhere.使用 .mjs,您基本上想重新编写代码以在任何地方进行依赖注入。 and functions to double fat arrows :P
和双胖箭头的功能:P
const makeFunctionThatUsesFoo = (fooInstance) => (funcAgs) => {
console.log('I feel secure, but stubs stoped working')
}
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