public void testNonEmpty_read_all_byteArray() throws IOException {
      fillContent("222222");
      byte[] array = new byte[6];
      assertEquals(6, file.read(0, array, 0, array.length));
      assertArrayEquals(bytes("222222"), array);
    }
Actual test cases for testing RegularFiles.
jimfs/src/test/java/com/google/common/jimfs/RegularFileTest.java