### Question:
DistrictHelper { public static String extractAbbrevFromKey(String key) { return key.substring(4); } private  DistrictHelper(); static boolean validateDistrictKey(String key); static int extractYearFromKey(String key); static String extractAbbrevFromKey(String key); static String generateKey(String districtAbbrev, int year);  }### Answer:
@Test public void testExtractAbbrevFromKey() { String key = "2015ne"; String abbrev = DistrictHelper.extractAbbrevFromKey(key); assertEquals(abbrev, "ne"); }