return NO_CHARS;
          }
        };
    EscaperAsserts.assertBasic(escaper);
    assertEquals("<tab>Fish <and> Chips<newline>", escaper.escape("\tFish & Chips\n"));

    // Verify that everything else is left unescaped.
    String safeChars = "\0\u0100\uD800\uDC00\uFFFF";
    assertEquals(safeChars, escaper.escape(safeChars));

    // Ensure that Unicode escapers behave correctly wrt badly formed input.

            return NO_CHARS;
          }
        };
    EscaperAsserts.assertBasic(escaper);
    assertEquals("<tab>Fish <and> Chips<newline>", escaper.escape("\tFish & Chips\n"));

    // Verify that everything else is left unescaped.
    String safeChars = "\0\u0100\uD800\uDC00\uFFFF";
    assertEquals(safeChars, escaper.escape(safeChars));

    // Ensure that Unicode escapers behave correctly wrt badly formed input.