Mocking Java enum to add a value to test fail case

Question

I have an enum switch more or less like this:

public static enum MyEnum {A, B}

public int foo(MyEnum value) {
    switch(value) {
        case(A):          


        

Answer 1

I would put the default case with one of enum cases:

  public static enum MyEnum {A, B}

  public int foo(MyEnum value) {
    if (value == null) throw new IllegalArgumentException("Do not know how to handle " + value);

    switch(value) {
        case(A):
           return calculateSomething();
        case(B):
        default:
           return calculateSomethingElse();
    }
  }