meteor/packages/html/tokenize_tests.js

var Scanner = HTML._$.Scanner;
var getComment = HTML._$.getComment;

Tinytest.add("html - comments", function (test) {
  var succeed = function (input, content) {
    var scanner = new Scanner(input);
    var result = getComment(scanner);
    test.isTrue(result);
    test.equal(scanner.pos, content.length + 7);
    test.equal(result, {
      t: 'Comment',
      v: content
    });
  };

  var ignore = function (input) {
    var scanner = new Scanner(input);
    var result = getComment(scanner);;
    test.isFalse(result);
    test.equal(scanner.pos, 0);
  };

  var fatal = function (input, messageContains) {
    var scanner = new Scanner(input);
    var error;
    try {
      getComment(scanner);
    } catch (e) {
      error = e;
    }
    test.isTrue(error);
    if (error)
      test.isTrue(messageContains && error.message.indexOf(messageContains) >= 0, error.message);
  };

  ignore("<!DOCTYPE>");
  ignore("<!-a");
  ignore("<--");
  ignore("<!");
  ignore("abc");
  ignore("<a");

  fatal('<!--', 'Unclosed');
  fatal('<!---', 'Unclosed');
  fatal('<!----', 'Unclosed');
  fatal('<!-- -', 'Unclosed');
  fatal('<!-- --', 'Unclosed');
  fatal('<!-- -- abcd', 'Unclosed');
  fatal('<!-- ->', 'Unclosed');
  fatal('<!-- a--b -->', 'cannot contain');
  fatal('<!--x--->', 'must end at first');

  fatal('<!-- a\u0000b -->', 'cannot contain');
  fatal('<!--\u0000 x-->', 'cannot contain');

  succeed('<!---->', '');
  succeed('<!---x-->', '-x');
  succeed('<!--x-->', 'x');
  succeed('<!-- hello - - world -->', ' hello - - world ');
});