### Question:
CallDepth { public int decrement() { int depth = get() - 1; set(depth); assert depth >= 0; return depth; } private  CallDepth(); static CallDepth get(Class<?> adviceClass); int increment(); boolean isNestedCallAndIncrement(); int decrement(); boolean isNestedCallAndDecrement();  }### Answer:
@Test void testNegativeCount() { assertThatThrownBy(() -> callDepth.decrement()).isInstanceOf(AssertionError.class); }