### Question:
UserHistoryProcessor { public List<Tuple> updateUserHistory(Tuple input) { List<Tuple> results = new ArrayList<>(); String user = input.getString("user"); String prod1 = input.getString("product"); String cat1 = input.getString("category"); String prodKey = prod1 + ":" + cat1; Set<String> productsNavigated = getUserNavigationHistory(user); if (!productsNavigated.contains(prodKey)) { for (String other : productsNavigated) { String[] ot = other.split(":"); String prod2 = ot[0]; String cat2 = ot[1]; results.add(TupleBuilder.tuple().of("product", prod1, "category", cat2)); results.add(TupleBuilder.tuple().of("product", prod2, "category",cat1)); } addProductToHistory(user, prodKey); } return results; } UserHistoryProcessor(RedisTemplate<String, String> redisTemplate); List<Tuple> updateUserHistory(Tuple input);  }### Answer:
@Test public void testUpdateUserHistory() { String content = "{\"user\":\"John\",\"product\":\"8\",\"type\":\"PRODUCT\", \"category\":\"Phones\"}"; Tuple event = TupleBuilder.fromString(content); Map<String, Set<String>> items = new HashMap<>(); Set<String> views = new HashSet<>(); views.add("0:Players"); views.add("2:Players"); views.add("17:TVs"); views.add("21:Mounts"); items.put("John", views); userHistoryProcessor.setUserNavigatedItems(items); List<Tuple> results = userHistoryProcessor.updateUserHistory(event); assertThat(results.size(), is(8)); int count8 = 0; int countPhones = 0; for (Tuple t : results) { int val; val = t.getInt("product"); if (val == 8) { assertThat(t.getString("category"), anyOf(is("Players"), is("TVs"), is("Mounts"))); count8++; } else { for (int product : new int[] {0, 2, 17, 21}) { if (val == product) { assertThat(t.getString("category"), is("Phones")); countPhones++; break; } } } } assertThat(count8, is(4)); assertThat(countPhones, is(4)); Set<String> history = redisTemplate.boundSetOps("history:John").members(); assertThat(history.size(), is(1)); assertThat(history.iterator().next(), is("8:Phones")); }