assertEqualsSame(expected, in, anyOf("-#").collapseFrom(in, replacement));
      assertEqualsSame(expected, in, anyOf("-#123").collapseFrom(in, replacement));
    }
  }

  private void doTestCollapseWithNoChange(String inout) {
    assertSame(inout, is('-').collapseFrom(inout, '_'));
    assertSame(inout, is('-').or(is('#')).collapseFrom(inout, '_'));

      assertEqualsSame(expected, in, anyOf("-#").collapseFrom(in, replacement));
      assertEqualsSame(expected, in, anyOf("-#123").collapseFrom(in, replacement));
    }
  }

  private void doTestCollapseWithNoChange(String inout) {
    assertSame(inout, is('-').collapseFrom(inout, '_'));
    assertSame(inout, is('-').or(is('#')).collapseFrom(inout, '_'));

   * BMP characters replaced by a single replacement character. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')
   * }
   *
   * ... returns {@code "b-p-r"}.
   *
   * <p>The default implementation uses {@link #indexIn(CharSequence)} to find the first matching