A Reusable Builder Class for Javascript Testing
- by Liam McLennan
Continuing on my series of builders for C# and Ruby here is the solution in Javascript. This is probably the implementation with which I am least happy. There are several parts that did not seem to fit the language. This time around I didn’t bother with a testing framework, I just append some values to the page with jQuery. Here is the test code: var initialiseBuilder = function() {
var builder = builderConstructor();
builder.configure({
'Person': function() { return {name: 'Liam', age: 26}},
'Property': function() { return {street: '127 Creek St', manager: builder.a('Person') }}
});
return builder;
};
var print = function(s) {
$('body').append(s + '<br/>');
};
var build = initialiseBuilder();
// get an object
liam = build.a('Person');
print(liam.name + ' is ' + liam.age);
// get a modified object
liam = build.a('Person', function(person) { person.age = 999; });
print(liam.name + ' is ' + liam.age);
home = build.a('Property');
print(home.street + ' manager: ' + home.manager.name);
and the implementation:
var builderConstructor = function() {
var that = {};
var defaults = {};
that.configure = function(d) {
defaults = d;
};
that.a = function(type, modifier) {
var o = defaults[type]();
if (modifier) {
modifier(o);
}
return o;
};
return that;
};
I still like javascript’s syntax for anonymous methods, defaults[type]() is much clearer than the Ruby equivalent @defaults[klass].call(). You can see the striking similarity between Ruby hashes and javascript objects. I also prefer modifier(o) to the equivalent Ruby, yield o.
