### Question:
Impression implements Serializable { public Long getTotal() { return h0.getT() + h1.getT() + h2.getT() + h3.getT(); } Impression();  Impression(H0 h0, H1 h1, H2 h2, H3 h3);  Impression(Double[] dayCounts);  Impression(double[] dayCounts);  Impression(Map map); Long getTotal(); double getValueForHIndex(int h_index); long countImpressions(double price, TargetingChannel.PriceModel priceModel); H1 getH1(); void setH1(H1 h1); H0 getH0(); void setH0(H0 h0); H2 getH2(); void setH2(H2 h2); H3 getH3(); void setH3(H3 h3); Integer getH_index(); void setH_index(Integer h_index); void adjustPositive(); List<Double> getHs(); static Impression add(Impression i1, Impression i2); static Impression subtract(Impression i1, Impression i2); static Impression multiply(Impression i1, double r); long getCountByPriceCategory(int priceCategory); long getIndividualHistogramCountByPriceCategory(int priceCategory); void adjustValue(int priceCategory, long t); @Override String toString(); static final int TOTAL_NUM_OF_PRICE_CATEGORIES; }### Answer:
@Test public void getTotal() { H0 h0 = new H0(); h0.setH("00"); h0.setT((long) 0); H1 h1 = new H1(); h1.setH("01"); h1.setT((long) 1); H2 h2 = new H2(); h2.setH("02"); h2.setT((long) 2); H3 h3 = new H3(); h3.setH("03"); h3.setT((long) 3); Impression imp = new Impression(h0, h1, h2, h3); assertEquals(6, imp.getTotal(), 0); Impression imp2 = new Impression(); assertEquals(0, imp2.getTotal(), 0); }