@Override
    public void rotate(IndexSet indexSet) {
        indexRotator.rotate(indexSet, this::shouldRotate);
    }
@Test
    public void shouldRotateThrowsISEIfIndexIsEmpty() {
        when(indexSet.getConfig()).thenReturn(indexSetConfig);
        when(indexSet.getNewestIndex()).thenReturn("");

        expectedException.expect(IllegalStateException.class);
        expectedException.expectMessage("Index name must not be null or empty");

        rotationStrategy.rotate(indexSet);
    }