Mocking new enum value to test default case in switch

Question

I'm trying to test a default case in a switch that checks an enum. I've seen a few posts and got to this solution:

int nValues = EnumType.values().length;
try (MockedStatic<EnumType> mocked = mockStatic(EnumType.class)) {
  val UNSUPPORTED = mock(EnumType.class);
  doReturn(nValues).when(UNSUPPORTED).ordinal();
  doReturn(nValues).when(UNSUPPORTED).getValue();
  doReturn("UNSUPPORTED").when(UNSUPPORTED).name();
  mocked.when(EnumType::values).thenReturn(new EnumType[] {
          EnumType.A,
          EnumType.B,
          EnumType.C,
          EnumType.D,
          UNSUPPORTED});

  assertThatThrownBy(() -> mapper.callSwitch(UNSUPPORTED))
          .isInstanceOf(CustomException.class);
}

However this gives me the following error on the switch statement

Java.lang.ArrayIndexOutOfBoundsException: Index 4 out of bounds for length 4

One of the comments on this answer https://stackoverflow.com/a/7233572/2696646 seems to describe a solution to my problem, but as far as I can see I did exactly that.

Here's my enum and switch:

public enum EnumType{
  A(0),
  B(1),
  C(2),
  D(3);
}

switch (status) {
  case A:
    return "aaaa";
  case B:
    return "bbbb";
  case C:
    return "cccc";
  case D:
    return "dddd";
  default:
    // throw some custom exception
}

Can anyone explain to me what I'm doing wrong?