@Test public void shouldReturnUnmodifiableComponentsWhenLocked() { // Given final ElementAggregator aggregator = new ElementAggregator(); // When aggregator.lock(); final List<TupleAdaptedBinaryOperator<String, ?>> components = aggregator.getComponents(); // Then try { components.add(null); fail("Exception expected"); } catch (final UnsupportedOperationException e) { assertNotNull(e); } }