private variables are null that are assigned using @Value in spring boot junit case

Question

I have below java class for which i have to write a junit test.

@Service
class My {
    @Value("${emp.name}")
    private String name;

    public void printName() {
        StringBuilder sb = new StringBuilder(name);
        //do some stuff
    }
}

Now I'm writing a test class for this java class that is like below.

@PrepareforTest({My.class})
public class MyTest {
   @InjectMocks
   My my;

   @Test
   public void printNameTest() {
       //Test code
   }
}

The problem here is i'm getting null pointer exception on StringBuilder sb = new StringBuilder(name); and test is breaking.

Anyone know how to load properties values in the test using @Value or pass the values to instance. I tried using reflection but it also gave error.

Of course it is `null`. You are using mockito to create (and mock) and instance and not Spring. — M. Deinum, Jun 17 '20 at 12:33

score 0 · Answer 1 · answered Jun 17 '20 at 12:29

0

Do not use field Injection, but instead pass it in the constructor. Makes it easier to test.

@Service
class My {

    private String name;

    public My(@Value("${emp.name}") String name) {
        this.name = name;
    }

    public void printName() {
        StringBuilder sb = new StringBuilder(name);
        //do some stuff
    }

}

Alternatively, use the ReflectionTestUtils. See: https://stackoverflow.com/a/17355595/2082699

answered Jun 17 '20 at 12:29

Tom Cools

1,098
8
23

Will a class with a parameterized constructor work with `PrepareforTest`? Will PowerMock actually use it? – Sotirios Delimanolis Jun 17 '20 at 13:06
I tried using reflection. But it is not working. Could you please tell me the example how can i use reflectiontestutills? – Pirate Jun 17 '20 at 17:02

score 0 · Answer 2 · answered Jun 17 '20 at 12:54

0

There is no annotation to tell Mockito @InjectMocks to just inject that value without doing any mocking or spying.

So you have two option :

either autowire My class and let's handle everything by springboot.
or mock the printName() response

answered Jun 17 '20 at 12:54

Abhishek Mishra

611
4
11

private variables are null that are assigned using @Value in spring boot junit case

2 Answers2