如何在Mockito中模拟enum.values（）

Question

First of all i'm learning java and mockito, did search and cannot find proper answer yet.

The pseudo code is like this

public enum ProdEnum {
    PROD1(1, "prod1"),
    PROD2(2, "prod2"),
    ......
    PROD99(2, "prod2");

    private final int id;
    private final String name;

    private ProdEnum(int id, String name) {
        this.id = id;
        this.name = name;
    }

    prublic String getName() { return this.name; }
}


public class enum1 {
   public static void main(String[] args) {
      // Prints "Hello, World" in the terminal window.
      System.out.println("Hello, World");

      List<String> prodNames = Array.stream(ProdEnum.values())
            .map(prodEnum::getName)
            .collect(Collectors.toList());

      // verify(prodNames);
   }
}

My question is in unit test, how to generate mocked prodNames ? Only 2 or 3 of the products needed for testing, In my unit test i tried this

List<ProdEnum> newProds = Arrays.asList(ProdEnum.PROD1, ProdEnum.PROD2);
when(ProdEnum.values()).thenReturn(newProds);

but it says Cannot resolve method 'thenReturn(java.util.List<...ProdEnum>)'

Thanks !

Answer 1

You cannot mock statics in vanilla Mockito.

If your up for a little refactor then:

1) Move enum.values() call into a package level method:

..
List<String> prodNames = Array.stream(getProdNames())
            .map(prodEnum::getName)
            .collect(Collectors.toList());
..

List<String> getProdNames(){
  return ProdEnum.values();
}

2) Spy on your SUT:

enum1 enumOneSpy = Mockito.spy(new enum1());

3) Mock the getProdNames() method:

doReturn(newProds).when(enumOneSpy).getProdNames();