David E. Wheeler
and 1 contributors


Test.Builder - Back end for building test libraries


  var Test = new Test.Builder();

  function ok (test, description) {
      Test.ok(test, description);


Test.Builder provides the buildings block upon which to write test libraries like Test.Simple and Test.More that can work together. All tests are expected to use a plan and to be run in an HTML element with its "id" attribute set to "test". See Test.Simple and Test.More for details. Users of this class, however, are expected to be folks who want to write test functions that interoperate with Test.Simple and Test.More.



This constant contains a string that defines the platform in which the tests are currently running. Possible values are:


A Web browser.


Adobe Director.


Windows Scripting Host.


  var Test = new Test.Builder();

Returns a new Test.Builder object. Since you generally only run one test per program, there should be one and only one Test.Builder object. So, in general, you should call Test.Builder.instance() to get at the singleton object used for all tests. Only use new Test.Builder() if you need to create a new Test.Builder object to, for example, test a Test.Builder-based test library.

  var Test = Test.Builder.instance();

Returns a Test.Builder object representing the current state of the test. No matter how many times you call Test.Builder.instance(), you'll get the same object. (This is called a singleton).


Reinitializes the Test.Builder singleton to its original state. Mostly useful for tests run in persistent environments where the same test might be run multiple times in the same process.

Setting up tests

These methods are for setting up tests and declaring how many there are. You usually only want to call one of these methods.

  Test.plan({ noPlan:  true     });
  Test.plan({ skipAll: reason   });
  Test.plan({ tests:   numTests });

A convenient way to set up your tests. Call this method and Test.Builder will print the appropriate headers and take the appropriate actions.

If you call plan(), don't call any of the other test setup methods.

    var max = Test.expectedTests();

Gets/sets the number of tests we expect this test to run and prints out the appropriate headers.


Declares that this test will run an indeterminate number tests.

  var plan = Test.hasPlan();

Find out whether a plan has been defined. plan is either null (no plan has been set) "noPlan" (indeterminate number of tests) or an integer (the number of expected tests).


Skips all the tests in the test file, using the given reason.

Running tests

These methods actually run the tests. The description argument is always optional.

  Test.ok(test, description);

Your basic test. Pass if test is true, fail if test is false. Returns a boolean indicating passage or failure.

  Test.isEq(got, expect, description);

Tests to see whether got is equivalent to expect.

  Test.isNum(got, expect, description);

Tests to see whether the numeric form of got is equivalent to the numeric form of expect as converted by Number().

  Test.isntEq(got, dontExpect, description);

The opposite of isEq(). Tests to see whether got is not equivalent to dontExpect.

  Test.isntNum(got, dontExpect, description);

The opposite of isNum(). Tests to see whether the numeric form of got is not equivalent to the numeric form of dontExpect as converted by Number().

  Test.like(got, /regex/, description);
  Test.like(got, 'regex', description);

Tests to see whether got matches the regular expression in regex. If a string is passed for the regex argument, it will be converted to a regular expression object for testing. If <got> is not a string, the test will fail.

  Test.unlike(got, /regex/, description);
  Test.unlike(got, 'regex', description);

The opposite of unlike(). Tests to see whether got does not match the regular expression in regex. If a string is passed for the regex argument, it will be converted to a regular expression object for testing. If <got> is not a string, the test will pass.

  Test.cmpOK(got, op, expect, description);

Performs a comparison of two values, got and expect. Specify any binary comparison operator as a string via the op argument. In addition to the usual JavaScript operators, cmpOK() also supports the Perl-style string comparison operators:

eq - String equal
ne - String not equal
lt - String less than
gt - String greater than
le - String less than or equal
ge - String greater than or equal

Indicates to the Test.Harness that things are going so badly all testing should terminate. This includes running any additional test files.


Skips the current test, reporting why.


Like skip(), only it will declare the test as failing and TODO.


Like skip(), only it skips all the rest of the tests you plan to run and terminates the test.

If you're running under "noPlan", it skips once and terminates the test.

Test style


Whether or not the test should output numbers. That is, this if true:

  ok 1
  ok 2
  ok 3

or this if false


Most useful when you can't depend on the test output order. Test.Harness will accept either, but avoid mixing the two styles. Defaults to true.


If set to true, no "1..N" header will be printed.


Normally, Test.Builder does some extra diagnostics when the test ends. It also changes the exit code as described below. If this is true, none of that will be done.


Controlling where the test output goes. It's ok for your test to change where document.write points to; Test.Builder's default output settings will not be affected.

    Test.diag(msg, msg2, msg3);

Prints out all of its arguments. All arguments are simply appended together for output.

Normally, it uses the failureOutput() handle, but if this is for a TODO test, the todoOutput() handle is used.

Output will be indented and marked with a "#" so as not to interfere with test output. A newline will be put on the end if there isn't one already.

We encourage using this method rather than outputting diagnostics directly.

Returns false. Why? Because diag() is often used in conjunction with a failing test (ok() || diag()) it "passes through" the failure.

    return ok(...) || diag(...);


These methods specify where test output and diagnostics will be sent. By default, in a browser they all default to appending to the element with the "test" ID or, failing that, to using document.write(). In Adobe Director, they use trace() for their output, and in Windows Scripting Host, they use WScript.StdOut.writeline(). If you wish to specify other functions that lack the apply() method, you'll need to supply them instead as custom anonymous functions that take a single argument (multiple arguments will be concatenated before being passed to the output function):

  Test.output(function (msg) { foo(msg) });

Function to call with normal "ok/not ok" test output.


Function to call with diagnostic output on test failures and diag.


Function to call with diagnostic about todo test failures and diag.


Function to call with warnings.


Function to which to pass any end messages (such as "Looks like you planed 8 tests but ran 2 extra").

Test Status and Info

    var currTest = Test.currentTest();

Gets/sets the current test number we're on. You usually shouldn't have to set this property.

If set forward, the details of the missing tests are filled in as "unknown". if set backward, the details of the intervening tests are deleted. You can erase history if you really want to.

    my @tests = Test.summary();

A simple summary of the tests so far returned as an array or boolean values, true for pass, false for fail. This is a logical pass/fail, so todos are passes.

Of course, test #1 is tests[0], etc...

    my @tests = Test.details();

Like summary(), but with a lot more detail.

  tests[testNum - 1] = {
      ok:        is the test considered a pass?
      actual_ok: did it literally say 'ok'?
      desc:      description of the test (if any)
      type:      type of test (if any, see below).
      reason:    reason for the above (if any)
  • "ok" is true if Test.Harness will consider the test to be a pass.

  • "actual_ok" is a reflection of whether or not the test literally printed "ok" or "not ok". This is for examining the result of "todo" tests.

  • "description is the description of the test.

  • "type" indicates if it was a special test. Normal tests have a type of "". Type can be one of the following:

    skip see skip()
    todo see todo()
    todo_skip see todoSkip()
    unknown see below

Sometimes the Test.Builder test counter is incremented without it printing any test output, for example, when currentTest() is changed. In these cases, Test.Builder doesn't know the result of the test, so it's type is "unknown". The details for these tests are filled in. They are considered ok, but the name and actual_ok is left null.

For example "not ok 23 - hole count # TODO insufficient donuts" would result in this structure:

  tests[22] = {          // 23 - 1, since arrays start from 0.
      ok:        1,      // logically, the test passed since it's todo
      actual_ok: 0,      // in absolute terms, it failed
      desc:      'hole count',
      type:      'todo',
      reason:    'insufficient donuts'
    TODO: {
        Test.todo(why, howMany);
        ...normal testing code goes here...

Declares a series of tests that you expect to fail and why. Perhaps it's because you haven't fixed a bug or haven't finished a new feature. The next howMany tests will be expected to fail and thus marked as "TODO" tests.

    var package = Test.caller();
    my(pack, file, line) = Test.caller();
    my(pack, file, line) = Test.caller(height);

Like the normal caller(), except it reports according to your level().

  var timeout = 3000;
  var asyncID = Test.beginAsync(timeout);
      function () {
          Test.ok(true, "Pass after 2 seconds");
      }, timeout - 1000

Sometimes you may need to run tests in an asynchronous process. Such processes can be started using window.setTimeout() or window.setInterval() in a browser, or by making an XMLHttpRequest call. In such cases, the tests might normally run after the test script has completed, and thus the summary message at the end of the test script will be incorrect--and the test results will appear after the summary.

To get around this problem, tell the Test.Builder object that you're running asyncronous tests by calling beginAsync(). The test script will not finish until you pass the ID returned by beginAsync() to endAsync(). If you've called beginAsync() with the optional timout argument, then the test will finish if endAsync() has not been called with the appropriate ID before the timeout has elapsed. The timeout can be specified in milliseconds.

  if (typeof JSAN != 'undefined') new JSAN().use('Test.Builder');
  else {
      if (typeof Test == 'undefined' || typeof Test.Builder == 'undefined')
          throw new Error(
              "You must load either JSAN or Test.Builder "
              + "before loading Test.Simple"

  Test.Simple = {};
  Test.Simple.EXPORT      = ['plan', 'ok'];
  Test.Simple.EXPORT_TAGS = { ':all': Test.Simple.EXPORT };
  Test.Simple.VERSION     = '0.29';

  // .... Declare exportable functions, then export them.

  if (typeof JSAN == 'undefined') Test.Builder.exporter(Test.Simple);

This method is used by Test.More and Test.Simple to export functions into the global namespace. It is only used if JSAN (http://www.openjsan.org/) is not available. Other test modules built with Test.Builder should also use this method to export functions. An optional second argument specifies the name space in which to export the functionls. If it is not defined, it defaults to the window object in browsers and the _global object in Director.


CPAN can provide the best examples. Test.Simple and Test.More both use Test.Builder.

See Also


Simple testing with a single testing function, ok(). Built with Test.Builder.


Offers a panoply of test functions for your testing pleasure. Also built with Test.Builder.


JSUnit: elaborate xUnit-style testing framework. Completely unrelated to Test.Builder.


  • Finish porting tests from Test::Simple.

  • Properly catch native exceptions, such as for syntax errors (is this even possible?).


Original Perl code by chromatic and maintained by Michael G Schwern <schwern@pobox.com>. Ported to JavaScript by David Wheeler <david@kineticode.com>.


Copyright 2002, 2004 by chromatic <chromatic@wgz.org> and Michael G Schwern <schwern@pobox.com>, 2005 by David Wheeler <david@kineticode.com>.

This program is free software; you can redistribute it and/or modify it under the terms of the Perl Artistic License or the GNU GPL.

See http://www.perl.com/perl/misc/Artistic.html and http://www.gnu.org/copyleft/gpl.html.

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