如何在angular 2中测试私有函数?
class FooBar {
private _status: number;
constructor( private foo : Bar ) {
this.initFooBar();
}
private initFooBar(){
this.foo.bar( "data" );
this._status = this.fooo.foo();
}
public get status(){
return this._status;
}
}
我找到了解决办法
将测试代码本身放在闭包中，或者在闭包中添加代码，以存储外部作用域中现有对象上局部变量的引用。
稍后使用工具提取测试代码。
http://philipwalton.com/articles/how-to-unit-test-private-functions-in-javascript/
如果你做过这个问题，请给我一个更好的解决方法。
P.S
大多数类似类型的问题的答案都没有给出问题的解决方案，这就是我问这个问题的原因
大多数开发人员说不要测试私有函数，但我不会说它们是错的还是对的，但我的案例中有必要测试私有函数。
正如许多人已经指出的那样，尽管您想要测试私有方法，但您不应该通过修改代码或编译器来让它为您工作。现代的TypeScript会拒绝人们迄今为止提供的大部分hack。
解决方案
TLDR;如果一个方法需要测试，那么您应该将代码解耦到一个类中，以便将该方法公开以供测试。
你拥有私有方法的原因是因为功能不一定属于那个类，因此如果功能不属于那里，它应该解耦到它自己的类中。
例子
我偶然看到了这篇文章，它很好地解释了应该如何处理私有方法的测试。它甚至涵盖了这里的一些方法，以及为什么它们是糟糕的实现。
https://patrickdesjardins.com/blog/how-to-unit-test-private-method-in-typescript-part-2
注意:这段代码摘自上面链接的博客(我复制了以防链接后面的内容发生变化)
之前
class User {
public getUserInformationToDisplay() {
//...
this.getUserAddress();
//...
}
private getUserAddress() {
//...
this.formatStreet();
//...
}
private formatStreet() {
//...
}
}
后
class User {
private address: Address;
public getUserInformationToDisplay() {
//...
address.format();
//...
}
}
class Address {
private format: StreetFormatter;
public format() {
//...
format.toString();
//...
}
}
class StreetFormatter {
public toString() {
// ...
}
}
结束笔记
You can implicitly test your private methods by making sure that conditions are met such that the code is called through the public interface. If the public interface does not call out to the private methods then that code is not providing any function and should be removed. In the example above there should be some effect that calling the private method should return ie: an object with an address. If there's not, for example the code emits an event in a private method, then you should start looking to decouple that so that it can be tested -- even in that example you would likely listen/subscribe to that event and would be able to test it that way. Decoupling leads to better testability and easier code maintenance later down the road as well.
正如许多人已经指出的那样，尽管您想要测试私有方法，但您不应该通过修改代码或编译器来让它为您工作。现代的TypeScript会拒绝人们迄今为止提供的大部分hack。
解决方案
TLDR;如果一个方法需要测试，那么您应该将代码解耦到一个类中，以便将该方法公开以供测试。
你拥有私有方法的原因是因为功能不一定属于那个类，因此如果功能不属于那里，它应该解耦到它自己的类中。
例子
我偶然看到了这篇文章，它很好地解释了应该如何处理私有方法的测试。它甚至涵盖了这里的一些方法，以及为什么它们是糟糕的实现。
https://patrickdesjardins.com/blog/how-to-unit-test-private-method-in-typescript-part-2
注意:这段代码摘自上面链接的博客(我复制了以防链接后面的内容发生变化)
之前
class User {
public getUserInformationToDisplay() {
//...
this.getUserAddress();
//...
}
private getUserAddress() {
//...
this.formatStreet();
//...
}
private formatStreet() {
//...
}
}
后
class User {
private address: Address;
public getUserInformationToDisplay() {
//...
address.format();
//...
}
}
class Address {
private format: StreetFormatter;
public format() {
//...
format.toString();
//...
}
}
class StreetFormatter {
public toString() {
// ...
}
}
结束笔记
You can implicitly test your private methods by making sure that conditions are met such that the code is called through the public interface. If the public interface does not call out to the private methods then that code is not providing any function and should be removed. In the example above there should be some effect that calling the private method should return ie: an object with an address. If there's not, for example the code emits an event in a private method, then you should start looking to decouple that so that it can be tested -- even in that example you would likely listen/subscribe to that event and would be able to test it that way. Decoupling leads to better testability and easier code maintenance later down the road as well.
“不要测试私有方法”的重点实际上是像使用它的人那样测试类。
如果你有一个带有5个方法的公共API，你的类的任何消费者都可以使用这些方法，因此你应该测试它们。使用者不应该访问类的私有方法/属性，这意味着在公共公开功能保持不变的情况下，可以更改私有成员。
如果依赖内部可扩展功能，请使用protected而不是private。
注意protected仍然是一个公共API(!)，只是使用方式不同。
class OverlyComplicatedCalculator {
public add(...numbers: number[]): number {
return this.calculate((a, b) => a + b, numbers);
}
// can't be used or tested via ".calculate()", but it is still part of your public API!
protected calculate(operation, operands) {
let result = operands[0];
for (let i = 1; i < operands.length; operands++) {
result = operation(result, operands[i]);
}
return result;
}
}
单元测试保护的属性与消费者使用它们的方式相同，通过子类化:
it('should be extensible via calculate()', () => {
class TestCalculator extends OverlyComplicatedCalculator {
public testWithArrays(array: any[]): any[] {
const concat = (a, b) => [].concat(a, b);
// tests the protected method
return this.calculate(concat, array);
}
}
let testCalc = new TestCalculator();
let result = testCalc.testWithArrays([1, 'two', 3]);
expect(result).toEqual([1, 'two', 3]);
});
你可以调用私有方法!
如果您遇到以下错误:
expect(new FooBar(/*...*/).initFooBar()).toEqual(/*...*/)
// TS2341: Property 'initFooBar' is private and only accessible within class 'FooBar'
只需使用// @ts-ignore:
// @ts-ignore
expect(new FooBar(/*...*/).initFooBar()).toEqual(/*...*/)
感谢@Moff452的评论。你也可以这样写:
expect(new FooBar(/*...*/)['initFooBar']()).toEqual(/*...*/)
更新:
@ts-expect-error是@ts-ignore的更好选择。看到的:
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-9.html#ts-ignore-or-ts-expect-error
