Escaper escaper = Escapers.builder().setSafeRange('a', 'z').build();
    assertThat(escaper.escape("The Quick Brown Fox")).isEqualTo("The Quick Brown Fox");
  }

  public void testBuilderInitialStateNoneUnsafe() {
    // No characters are unsafe by default (safeMin == 0, safeMax == 0xFFFF).
    Escaper escaper = Escapers.builder().setUnsafeReplacement("X").build();
    assertThat(escaper.escape("\0\uFFFF")).isEqualTo("\0\uFFFF");

    Escaper escaper = Escapers.builder().setSafeRange('a', 'z').build();
    assertThat(escaper.escape("The Quick Brown Fox")).isEqualTo("The Quick Brown Fox");
  }

  public void testBuilderInitialStateNoneUnsafe() {
    // No characters are unsafe by default (safeMin == 0, safeMax == 0xFFFF).
    Escaper escaper = Escapers.builder().setUnsafeReplacement("X").build();
    assertThat(escaper.escape("\0\uFFFF")).isEqualTo("\0\uFFFF");

    UnicodeEscaper e = (UnicodeEscaper) urlFormParameterEscaper();
    // Verify that these are the same escaper (as documented)
    assertThat(urlFormParameterEscaper()).isSameInstanceAs(e);
    assertBasicUrlEscaper(e);

    /*
     * Specified as safe by RFC 2396 but not by java.net.URLEncoder. These tests will start failing
     * when the escaper is made compliant with RFC 2396, but that's a good thing (just change them
     * to assertUnescaped).

    }
  }

  public void testFalsePositivesForNextEscapedIndex() {
    UnicodeEscaper e =
        new UnicodeEscaper() {
          // Canonical escaper method that only escapes lower case ASCII letters.
          @Override
          protected char @Nullable [] escape(int cp) {
            return ('a' <= cp && cp <= 'z') ? new char[] {Character.toUpperCase((char) cp)} : null;
          }

    UnicodeEscaper e = (UnicodeEscaper) urlFormParameterEscaper();
    // Verify that these are the same escaper (as documented)
    assertThat(urlFormParameterEscaper()).isSameInstanceAs(e);
    assertBasicUrlEscaper(e);

    /*
     * Specified as safe by RFC 2396 but not by java.net.URLEncoder. These tests will start failing
     * when the escaper is made compliant with RFC 2396, but that's a good thing (just change them
     * to assertUnescaped).

    assertUnicodeEscaping(e, "%F4%8F%BF%BF", '\uDBFF', '\uDFFF');

    // simple string tests
    assertThat(e.escape("")).isEqualTo("");
    assertThat(e.escape("safestring")).isEqualTo("safestring");
    assertThat(e.escape("embedded\0null")).isEqualTo("embedded%00null");
    assertThat(e.escape("max\uffffchar")).isEqualTo("max%EF%BF%BFchar");
  }

  /** Tests the various ways that the space character can be handled */

    assertUnicodeEscaping(e, "%F4%8F%BF%BF", '\uDBFF', '\uDFFF');

    // simple string tests
    assertThat(e.escape("")).isEqualTo("");
    assertThat(e.escape("safestring")).isEqualTo("safestring");
    assertThat(e.escape("embedded\0null")).isEqualTo("embedded%00null");
    assertThat(e.escape("max\uffffchar")).isEqualTo("max%EF%BF%BFchar");
  }

  /** Tests the various ways that the space character can be handled */

    assertThat(e.escape("")).isEqualTo("");
    assertThat(e.escape("safestring")).isEqualTo("safestring");
    assertThat(e.escape("embedded\0null")).isEqualTo("embedded%00null");
    assertThat(e.escape("max\uffffchar")).isEqualTo("max%EF%BF%BFchar");
  }

  // Helper to assert common expected behaviour of uri escapers.
  static void assertBasicUrlEscaper(UnicodeEscaper e) {

    assertThat(e.escape("")).isEqualTo("");
    assertThat(e.escape("safestring")).isEqualTo("safestring");
    assertThat(e.escape("embedded\0null")).isEqualTo("embedded%00null");
    assertThat(e.escape("max\uffffchar")).isEqualTo("max%EF%BF%BFchar");
  }

  // Helper to assert common expected behaviour of uri escapers.
  static void assertBasicUrlEscaper(UnicodeEscaper e) {

    // Test quotes are escaped.
    assertThat(xmlAttributeEscaper.escape("\"test\"")).isEqualTo(""test"");
    assertThat(xmlAttributeEscaper.escape("'test'")).isEqualTo("'test'");
    // Test all escapes
    assertThat(xmlAttributeEscaper.escape("a\"b<c>d&e\"f'"))
        .isEqualTo("a&quot;b&lt;c&gt;d&amp;e&quot;f&apos;");
    // Test '\t', '\n' and '\r' are escaped.