map.put(key1, "value 1");
map.put(key2, "value 2");
map.put(key3, "value 3");
assertTrue(map.size() == 3);
assertTrue(map.containsKey(key1));
assertTrue(map.containsKey(key2));
assertTrue(map.containsKey(key3));
map.remove(key2);
assertTrue(map.size() == 2);
assertTrue(map.containsKey(key1));