### Question:
MapFileDriver implements PlinkFileParser { public long getNrOfElements() throws IOException { if (nrElements == -1) nrElements = getNumberOfNonEmptyLines(file, FILE_ENCODING); return nrElements; } MapFileDriver(File mapFile);  MapFileDriver(File mapFile, char separator);  MapFileDriver(File mapFile, String separators); List<MapEntry> getEntries(final long from, final long to); List<MapEntry> getAllEntries(); static MapEntry parseEntry(String line, String separators); long getNrOfElements(); @Override void close(); void reset();  }### Answer:
@Test public void MAP_construct() throws Exception { assertEquals(10, mapfd.getNrOfElements()); }