public void testNonEmpty_write_partial_fromBeforeEnd_singleBuffer() throws IOException {
      fillContent("22222222");
      assertEquals(3, file.write(6, buffer("111")));
      assertContentEquals("222222111", file);
    }
Actual test cases for testing RegularFiles.
jimfs/src/test/java/com/google/common/jimfs/RegularFileTest.java