### Question:
BeanBackedELResolver extends AbstractELResolver { @Override protected boolean isAvailable() { return getBean() != null; }    }### Answer:
@Test public void shouldBeAvailableOnlyWhenHasBean() throws Exception { assertThat(this.resolver.isAvailable(), is(true)); this.bean = null; assertThat(this.resolver.isAvailable(), is(false)); }