### Question:
MaxFunction extends AggregateFunction<JsonNode, Double> { @Override public Double compute() { return maxValue; }  @Override AggregateFunction addValue(JsonNode value); @Override Double compute(); @Override AggregateFunction<JsonNode, Double> merge(AggregateFunction<JsonNode, Double> newValue);  }### Answer:
@Test public void shouldReturnNaNWhenNoValue() { MaxFunction maxFunction =new MaxFunction(); assertThat(maxFunction.compute()).isEqualTo(Double.NaN); }