Category Archives: Code

Software Development

A javascript unit testing framework in 50 lines – plus some assertions

Surprised by a TDD session at XP-Man in which we rolled our own unit test framework from scratch – using the growing framework itself to test itself as it grew – I added some basic assertions to my 50 line javascript test runner.

I suggest that assertions should be thought of as separate to a test runner. Assertions are at the heart of – and should grow into – your domain specific testing language. So you should think of assretions as owned by your application, not the testing framework. As your application grows, so domain specific assertions should grow. A testing framework should probably provide minimal assertions for the language it runs on: the ‘primitive’ true/false/equal/notEqual assertions which will be used to define more domain specific assertions; and doing the legwork of tedious but common cases, such as testing equality by value of complex objects and collections.

In the case of javascript, the below might do. The tricky thing for assertions is to come up with something that is fluent and not verbose. C# extension methods are perfect for this. In javascript one could add methods to Object.prototype, but that doesn’t have the same scoping restriction as C# so feels too much like trampling all over everyone else’s garden: it’s poor namespacing and a failure of good manners.

/* Assertions for a test framework. */

function Assert(actual, assertionGender){
    this.Expected=  assertionGender ? "Expected" : "Did not expect";

function assert(actual){return new Assert(actual, true);}
function assertNot(actual){return new Assert(actual, false);}

Assert.prototype.IsTrue = function(msg){
    if( this.actual == this.notted ){ throw msg||this.Expected + " true.";}

Assert.prototype.Equals = function(expected,msg){
    if( (this.actual==expected) == this.notted ){
        throw msg|| this.Expected + " " + this.actual + " to equal " + expected ;

Assert.prototype.EqualsByPropertyValue = function(expected,msg){
    var actualValue =  JSON.stringify( this.actual );
    var expectedValue = JSON.stringify( expected );
    if( (actualValue == expectedValue) == this.notted ){
        throw msg|| this.Expected + " " + actualValue + " to equal " + expectedValue + " by value";

    new Specification("SpecificationsForPrimitiveAssertionPasses",{
        isTrueShouldBeTrueForTrue : function(){
        equalsShouldPassForEqualArguments : function(){
            assert( 1+1 ).Equals( 2 );
        equalsByPropertyValueShouldPassForValueEqualArguments : function(){
            assert( { a: "a", b : function(){ return "b";}} )
                .EqualsByPropertyValue( { a: "a", b : function(){ return "b";}} );
        assertNotShouldReverseTheOutcomeOfAnAssertion : function(){
            assertNot({ a: "a"}).EqualsByPropertyValue( { a: "b"});

    new Specification("SpecificationsForPrimitiveAssertion_Failures",{
        isTrueShouldNotBeTrueForFalse : function(){
        equalsShouldFailForNonEqualArguments : function(){
        equalsByPropertyValueShouldFailForDifferingPropertyValues : function(){
            assert( { a: "a" } ).EqualsByPropertyValue( { a: "A" } );
        equalsByPropertyValueShouldFailForDifferingProperties : function(){
            assert( { a: "a" } ).EqualsByPropertyValue( { aa: "a" } );
        assertNotShouldReverseTheOutcomeOfIsTrue : function(){
            assertNot({ a: "a"}).EqualsByPropertyValue( { a: "a"});
        assertNotShouldReverseTheOutcomeOfEquals : function(){
        assertNotShouldReverseTheOutcomeOfEqualsByValue : function(){
            assertNot({ a: "a"}).EqualsByPropertyValue( { a: "a"});
        assertTrueFailureWithCustomerMessageShouldOutputCustomMessage : function(){
            assert(false).IsTrue("This assertion failure should output this custom message");
        assertEqualsFailureWithCustomerMessageShouldOutputCustomMessage : function(){
            assert(1).Equals(2, "This assertion failure should output this custom message");
        assertEqualsByValueFailureWithCustomerMessageShouldOutputCustomMessage : function(){
            assert({a:"a"}).EqualsByPropertyValue( 1, "This assertion failure should output this custom message");


A javascript unit testing framework in 50 lines

Last week at xp-man we did some TDD practise – by writing a tdd framework from scratch. The surprise was, how easy it was. So here, to my surprise, a very-bare-bones javascript unit test framework in 50 lines of code including the passing unit tests for the framework itself.

/* */

function Specification( name, tests, outputContainer ){ name;
    this.tests= tests;
    this.outputContainer= outputContainer || $('#testResults');

Specification.prototype = {
    name : 'UnnamedSpecification',
    tests : {},
    outputContainer : null,

    addMyselfToUI : function(){
        this.outputContainer.append( "<li><h3>" + +"</h3><ul id='" + + "'></ul></li>");

    testDomId:function (test) {
        return + "_" + test;

    addTestToUI : function addTestToUI( test ){
        $('#' + "<li id='" + this.testDomId(test) + "'>" + test + "<input type='checkbox'/></li>");

    markTestPassed : function( test ){
        $("#" + this.testDomId(test) + " input").prop("checked",true);

    markTestFailed : function( test, ex ){
        $("#" + this.testDomId(test) + " input").prop("checked",false);
        $("#" + this.testDomId(test) + " input").after("<ul>Output:<li>" + ex.toString() + "</li></ul>");

    runTest : function (test) {
        } catch(ex)  {
            this.markTestFailed(test, ex);

    runTests : function(){

        for (var test in this.tests) {
            if (this.tests.hasOwnProperty(test)) this.runTest( test );

     new Specification("TestFrameworkSpecifications", {

        aTestShouldAddItselfInTheTestResults:function() {},

        aPassingTestShouldTickTheCheckbox : function() {},

        aFailingTestShouldUntickTheCheckbox:function () {
            throw "This thrown exception should appear in the output, indicating a failure";

And the html doc to load and run it:

    <title>Minimal Javascript Test Framework</title>
    <script type="text/javascript" src="js/jquery-1.8.2.js"></script>
    <script type="text/javascript" src="js/wsl-testframework.js"></script>
<ul id="testResults">

As written, I admit a dependency on jQuery, but you can replace that with document.write(). The obvious omission is a bundle of pre-defined assertions, but if you are developing a domain specific testing language then assertions should be part of that package, not part of the test running framework.

The obvious oddity is that the test suite demonstrates its test failure behaviour by failing a test; and you see that that is the correct result by inspecting the output.

This has led me to think that the TDD way to learn a new language is … to write a TDD framework for it.

Fastest XML Editor

The really fasted XML editor I’ve ever used is XMLMarker which loads a 5MB file in a fraction of a second. When editing, it shows the XML simultaneously in tree, text and ‘Data Grid’ views which is quite impressive as are a couple of its other features:

  • You can edit data in the data view, not just in the text view
  • If you ‘break’ the document by editing the markup in text view, the data and tree views still work (arguably a dangerous feature: caveat user)

But I’m often doing RegEx search and replace, which XML Marker doesn’t do, and often editing text as well as xml. Notepad++ is quite speedy and can do regexes, but Sublime Text 2 does regex search and replace much better: it does live highlighting of what its found as you type, so you can ‘debug’ your regexing on the fly.

Everyone wants xml pretty printing (well, re-indenting), which for Sublime Text 2 is done by first installing the package manager and then installing the ‘Indent XML’ package. Package Management in Sublime Text is a bit command-liney, so do read Mr. Bond’s instructions.

sp_WhoLock – a T-SQL stored proc combining sp_who and sp_lock to show who’s locking what and how much

Run this query, or remove the comments to actually create a stored proc.
Note that SQL pre-2008 requires a field to be commented out of the query, as noted inline.

--Create Procedure WhoLock

if object_id('tempdb..#locksummary') is not null Drop table #locksummary
if object_id('tempdb..#lock') is not null Drop table #lock
create table #lock (    spid int,    dbid int,    objId int,    indId int,    Type char(4),    resource nchar(32),    Mode char(8),    status char(6))
Insert into #lock exec sp_lock
if object_id('tempdb..#who') is not null Drop table #who
create table #who (     spid int, ecid int, status char(30),
            loginame char(128), hostname char(128),
            blk char(5), dbname char(128), cmd char(16)
            , request_id INT --Remove this line for SQL 2005 or earlier
Insert into #who exec sp_who
Print '-----------------------------------------'
Print 'Lock Summary for ' + @@servername  + ' (excluding tempdb):'
Print '-----------------------------------------' + Char(10)
Select     left(loginame, 28) as loginame, 
    left(db_name(dbid),128) as DB,
    left(object_name(objID),30) as object,
    max(mode) as [ToLevel],
    Count(*) as [How Many],
    Max(Case When mode= 'X' Then cmd Else null End) as [Xclusive lock for command],
    l.spid, hostname
into #LockSummary
from #lock l join #who w on l.spid= w.spid
where dbID != db_id('tempdb') and l.status='GRANT'
group by dbID, objID, l.spid, hostname, loginame

Select * from #LockSummary order by [ToLevel] Desc, [How Many] Desc, loginame, DB, object

Print '--------'
Print 'Who is blocking:'
Print '--------' + char(10)
SELECT p.spid
,convert(char(12), db_name
, program_name
, p.loginame
, convert(char(12), hostname) hostname
, cmd
, p.status
, p.blocked
, login_time
, last_batch
, p.spid
FROM      master..sysprocesses p
JOIN      master..sysdatabases d ON p.dbid =  d.dbid
          FROM      master..sysprocesses p2
          WHERE     p2.blocked = p.spid )

Print '--------'
Print 'Details:'
Print '--------' + char(10)
Select     left(loginame, 30) as loginame,  l.spid,
    left(db_name(dbid),15) as DB,
    left(object_name(objID),40) as object,
    mode ,
from #lock l join #who w on l.spid= w.spid
where dbID != db_id('tempdb') and blk <>0
Order by mode desc, blk, loginame, dbID, objID, l.status

Although this is a bare metal approach to investigating sql contention, the query does show you actual login names, so it enables you to join up technical issues with affected/affecting customers.

F# on Mac and Linux

is not, in 2012, in a great state. There are 2 not-great options and I add here a third, also not-great option. It has the advantage of working, and not requiring you to learn emacs. (Jump straight to F# with Sublime)

F# on MonoDevelop

The F# language bindings for MonoDevelop broke after version 2.4. You can get MonoDevelop version 2.4 by consulting the wayback machine for the MonoDevelop Download page at July 2011. You can then use the fsharpbindings and instructions from
Personally I fould MonoDeveloper before 2.6 more prone to crashing, and I couldn’t get 2.4 working with FSharp.

F# on Aquamacs

If you’re an emacs fan, then you won’t need my help to find and install the f# mode for it.
For emacs newbies on the Mac with a day to burn on the learning curve, a couple of the answers on stackover gives you some clue as to how to get fsharp working:

F# with Sublime Text 2 (Quick and Dirty)

This was the best I could do in 2 hours:

  1. Get Sublime Text 2
  2. In the Sublime text menu : Tools – Build System – New Build System
    	"cmd": ["/usr/bin/fsharpcandrun", "$file"]

    and save as fsharp.sublime-build .

  3. At a terminal command line, use your favourite editor to save this file as /usr/bin/fsharpcandrun :
    fsharpc "$1" && nameafterquote=${1#\"} && exe=${nameafterquote%.*}.exe && mono "$exe" && echo done
  4. Make it executable, again from a terminal command line:
    sudo chmod a+x /usr/bin/fsharpcandrun

    The password that sudo asks your for is your login password.

  5. If your new favourite editor is in fact Sublime, you can save files in directories requiring sudo-ed permissions by putting a command line alias for sublime in your ~/.bash_profile script:
    alias edit='open -a /Applications/Sublime\ Text\\ Text\ 2'

    and typing edit foo.txt to open Sublime

  6. Choose Tool — build system — fsharp in Sublime
  7. Now, <f7> your file. It should compile and run. At least, it did for me.
  8. Get some kind of syntax colouring by creating a .fs file, and then choosing View — Syntax — Open all with current extension as … OCaml. This is because F# is near enough to OCaml for the colouring to be pretty good.

I wouldn’t call this great, but it will do for the moment. It only “builds” a single file, which is hardly a build system. But it does give you syntax colouring and compile-and-run for learning F#.

The next step forwards might be to modify the bash script to fsharpc a list of files, or all files in the directory of the file to be run.