PowerMockito+Junit - 模拟 System.getenv

Question

我试图在课堂上嘲笑的路线是：

String x[] = System.getenv("values").split(",")
for(int i=0;i<=x.length;i++){
  //do something
}

据我所写如下：

@RunWith(PowerMockRunner.class)
   @PrepareForTest({System.class})
   public class test{
           @Test
           public void junk(){

            PowerMockito.mockStatic(System.class);
            PowerMockito.when( System.getenv("values"))).thenReturn("ab,cd"); 
           }

         }

在调试时，我在 for 循环行中得到空指针。在代码库中检查 System.getenv("values") 时，仍然发现它为空

请赞成决议

编辑：确切的问题可复制场景：

package com.xyz.service.impl;

public class Junkclass {
    public String tests(){
        String xx[] = System.getenv("values").split(",");
        for (int i = 0; i < xx.length; i++) {
            return xx[i];
        }
        return null;
    }
}

package com.xyz.service.impl
@InjectMocks
@Autowired
Junkclass jclass;

@Test
    public void junk() {
        String x = "ab,cd";

        PowerMockito.mockStatic(System.class);

        // establish an expectation on System.getenv("values")
        PowerMockito.when(System.getenv("values")).thenReturn(x);

        // invoke System.getenv("values") and assert that your expectation was applied correctly
        Assert.assertEquals(x, System.getenv("values"));
        jclass.tests();

    }

Answer 1

在您的测试用例中，您正在调用，System.getenv("values").split(",")但您没有告诉 PowerMock 从中返回任何内容，System.getenv("values")因此您的代码在尝试调用split(",")来自System.getenv("values").

我不清楚您测试的目的，但以下测试将通过，并显示如何设置期望值System.getenv("values")：

@Test
public void junk() {
    String input = "ab,cd";

    PowerMockito.mockStatic(System.class);

    // establish an expectation on System.getenv("values")
    PowerMockito.when(System.getenv("values")).thenReturn(input);

    // invoke System.getenv("values") and assert that your expectation was applied correctly
    Assert.assertEquals(input, System.getenv("values"));

    String x[] = System.getenv("values").split(",");
    for (int i = 0; i < x.length; i++) {
        System.out.println(x[i]);
    }
}

上面的代码会打印出：

ab
cd

更新：

基于上述问题中“确切场景”的规定，以下测试将通过，即System.getenv("values")在junkclass.tests()...中调用时将返回模拟值。

@RunWith(PowerMockRunner.class)
@PrepareForTest({System.class, junkclass.class})
public class Wtf {

    @Test
    public void junk() {
        String x = "ab,cd";

        PowerMockito.mockStatic(System.class);

        // establish an expectation on System.getenv("values")
        PowerMockito.when(System.getenv("values")).thenReturn(x);

        // invoke System.getenv("values") and assert that your expectation was applied correctly
        Assert.assertEquals(x, System.getenv("values"));
        jclass.tests();
    }
}