assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"
            + "abcdefghijklmnopqrstuvwxyz"
            + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "1234567890";
    assertEquals(s, xmlEscaper.escape(s));

    // Test ASCII control characters.
    for (char ch = 0; ch < 0x20; ch++) {