public void testEmpty_write_partialByteArray_atNonZeroPosition() throws IOException {
      byte[] bytes = bytes("2211111122");
      file.write(5, bytes, 2, 6);
      assertContentEquals("00000111111", file);
    }
Actual test cases for testing RegularFiles.
jimfs/src/test/java/com/google/common/jimfs/RegularFileTest.java