}
            return index;
          }
        };
    assertEquals("\0HELLO \uD800\uDC00 WORLD!\n", e.escape("\0HeLLo \uD800\uDC00 WorlD!\n"));
  }

  public void testCodePointAt_indexOutOfBoundsException() {
    assertThrows(
        IndexOutOfBoundsException.class, () -> UnicodeEscaper.codePointAt("Testing...", 4, 2));
  }

  private static String escapeAsString(Escaper e, String s) {

            }
            return index;
          }
        };
    assertEquals("\0HELLO \uD800\uDC00 WORLD!\n", e.escape("\0HeLLo \uD800\uDC00 WorlD!\n"));
  }

  public void testCodePointAt_indexOutOfBoundsException() {
    assertThrows(
        IndexOutOfBoundsException.class, () -> UnicodeEscaper.codePointAt("Testing...", 4, 2));
  }

  private static String escapeAsString(Escaper e, String s) {