Getting Started

use : rely on EasyMock or Mockito and a test framework

Bypass Encapsulation mock 繞過封裝

翻譯自
https://github.com/powermock/powermock/wiki/Bypass-Encapsulation

Quick summary

Whitebox

class provides a set of methods which could you help bypass encapsulation if it required. Usually, it's not a good idea to get/modify non-public fields, but sometimes it's only way to cover code by test for future refactoring.

1. Use Whitebox.setInternalState(..) to set a non-public member of an instance or class. 設(shè)置內(nèi)部私有成員
2. Use Whitebox.getInternalState(..) to get a non-public member of an instance or class. 獲取內(nèi)部私有成員
3. Use Whitebox.invokeMethod(..) to invoke a non-public method of an instance or class. 調(diào)用私有方法
4. Use Whitebox.invokeConstructor(..) to create an instance of a class with a private constructor. 調(diào)用私有構(gòu)造函數(shù)

舉例

• 1 調(diào)用私有方法

private int sum(int a, int b) {
    return a+b;
}

int sum = Whitebox.<Integer> invokeMethod(myInstance, "sum", 1, 2);

• 2 私有方法重載情況

...
private int myMethod(int id) {      
    return 2*id;
}

private int myMethod(Integer id) {      
        return 3*id;
}
...

根據(jù)傳入?yún)?shù)class判斷用哪個(gè)

int result = Whitebox.<Integer> invokeMethod(myInstance, new Class<?>[]{int.class}, "myMethod", 1);

• 3 調(diào)用私有構(gòu)造器

public class PrivateConstructorInstantiationDemo {

    private final int state;

    private PrivateConstructorInstantiationDemo(int state) {
        this.state = state;
    }

    public int getState() {
        return state;
    }
}

調(diào)用：

PrivateConstructorInstantiationDemo instance =  WhiteBox.invokeConstructor(
                PrivateConstructorInstantiationDemo.class, 43);

• 4. 構(gòu)造器重載的情況

public class PrivateConstructorInstantiationDemo {

    private final int state;

    private PrivateConstructorInstantiationDemo(int state) {
        this.state = state;
    }

    private PrivateConstructorInstantiationDemo(Integer state) {
              this.state = state;
              // do something else
    }

    public int getState() {
        return state;
    }
}

調(diào)用：

PrivateConstructorInstantiationDemo instance = Whitebox.invokeConstructor(PrivateConstructorInstantiationDemo.class, new Class<?>[]{Integer.class}, 43);