使用 Mockito 模拟方法的局部变量

问题描述

我有一个需要测试的类A.以下是A的定义:

I have a class A that needs to the tested. The following is the definition of A:

public class A {
    public void methodOne(int argument) {
        //some operations
        methodTwo(int argument);
        //some operations
    }

    private void methodTwo(int argument) {
        DateTime dateTime = new DateTime();
        //use dateTime to perform some operations
    }
}

并且基于 dateTime 值，一些数据将被操作，从数据库中检索.对于此数据库，这些值通过 JSON 文件进行持久化.

And based on the dateTime value some data is to be manipulated, retrieved from the database. For this database, the values are persisted via a JSON file.

这使事情变得复杂.我需要的是在测试时将 dateTime 设置为某个特定日期.有没有办法可以使用 mockito 模拟局部变量的值?

This complicates things. What I need is to set the dateTime to some specific date while it is being tested. Is there a way I can mock a local variable's value using mockito?

推荐答案

你不能模拟一个局部变量.但是，您可以做的是将其创建提取到 protected 方法并 spy 它:

You cannot mock a local variable. What you could do, however, is extract its creation to a protected method and spy it:

public class A {
  public void methodOne(int argument) {
    //some operations
    methodTwo(int argument);
    //some operations
  }

  private void methodTwo(int argument) {
    DateTime dateTime = createDateTime();
    //use dateTime to perform some operations
  }

  protected DateTime createDateTime() {
    return new DateTime();
  }
}

public class ATest {
  @Test
  public void testMethodOne() {
    DateTime dt = new DateTime (/* some known parameters... */);
    A a = Mockito.spy(new A());
    doReturn(dt).when(a).createDateTime();
    int arg = 0; // Or some meaningful value...
    a.methodOne(arg);
    // assert the result
}

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