### Question:
RegionFile implements AutoCloseable { public synchronized byte[] read(int chunkX, int chunkY, int chunkZ) throws IOException { int startSector = chunkStartSectors[getChunkIndex(chunkX, chunkY, chunkZ)]; if (startSector == -1) { return null; } int sectorPosition = getSectorPosition(startSector); file.seek(sectorPosition); int length = file.readInt(); byte[] data = new byte[length]; file.read(data); return data; } RegionFile(File file); synchronized void write(int chunkX, int chunkY, int chunkZ, byte[] data, int length); synchronized byte[] read(int chunkX, int chunkY, int chunkZ); boolean hasChunk(int chunkX, int chunkY, int chunkZ); @Override void close();  }### Answer:
@Test void read() throws IOException { assertArrayEquals(oneSectorData, regionFile.read(0, 0, 0)); assertArrayEquals(twoSectorData, regionFile.read(15, 0, 0)); assertArrayEquals(oneAndHalfSectorData, regionFile.read(0, 15, 0)); }