Today it’s a quick one. It bite me few times already so it deserves a post, if not to help you, then to make me remember.
Sometimes I write simple test for parameter-less function and then
jasmine-node sees the test, but do not recognize assertion, reporting something like
1 tests, 0 assertions, 0 failures
while clearly I have some assertions (a.k.a. expectations) defined! See code below:
I’m so used to
CoffeeScript right now that all seems to be OK for this code. Yet there is an issue in here.
TDD want’s me to write failing test first so it is easy to spot that test passes even though it should not so seeing green test when I expect it to be red indicates that something is wrong). Can you see what’s wrong?
CoffeeScript allows to call function without using parenthesis – it automatically adds them to include all rest of line as parameters. Pretty nice when used good, code seems clearer, more readable once you get used to it (at least to me, at least now). But here it bites us. You see, when function takes no parameters providing parenthesis to call is obligatory – they won’t be added automatically since it would make returning function impossible (or it would require different language feature to return function pointer, which would not be obvious for developers).
Correct code, that actually calls assertsions is presented below:
See what changes? Two sets of parenthesis added: one to call
getValue and the other to
toBeNull – since both are parameter-less! Now we finally get red test, as expected. Hope I will remember it next time.
Last time I’ve shown how to configure everything so that multiple files can easily be used to separate classes and how tests can include all required code by taking advantage of
nodeJs test runner. We left it with test running fine but noting that this will not work for
html test runner. Let’s see how it should be configured to check if I was right
First thing we will need will be
jasmine code to make it all work – obviously. We can get it for free (awsome
MIT license) from github: jasmine downloads (if it is not working go to main project page jasmine and try to find where they moved download page). I’ve downloaded latest version available (1.3.1 at the time of writting this post) and unpacked it in my
./spec directory. This zip file contained required
SpecRunner.html file with preconfigured file and dependencies for fast and easy runnig specifications. There were also included some example specs and source codes but I’ve removed those as not needed.
SpecRunner.html file we can see that it’s just an ordinary
jasmine so that everything is working and looking nice. There are also example of specifications and source code inclusions – but I’ve removed those since I’ve removed sample files, like said before. Closer to the bottom we can also see
Seeing two sections – one for source files and the other for specifications – I’ve added references to my files I wish to run in this test runner.
As you can see those references lead to
lib directory – it is output directory for my compiled files (which I compiled simply by calling
coffee --output .\lib --compile .). Suppose that you do nothing more and just open the file in web browser – it should run all specs included. Try that and see.
I did and I got empty page and few
require is not defined. Sure it’s not – it is
nodeJs function not present in
jasmine by default. And we do use it in our specifications and classes. More – even if this method was defined it probably would not work as we hope it would –
exports class would also not be defined as we use
window object to pass references to our classes when running outside
nodeJs (see previous blog).
But think about that for a second – what’s the point of using
require function in first place? To include other files. But we already included them in
html definition so they are ready to use. We’ve taken care of
exports object not being defined also by using
window object. Solution to the problem seems pretty easy – write simple require function that will return reference to
window object and rest of the code can stay unchanged. So I did – added this little snippet below
jasmine references in runner file:
Why does it work? Because
require function – cool I have one, I will run it! It does not even care that function signature does not match – apparently it does not need all those arguments you’ve provided so why bother. Return value type is different (
window is for sure different class than
exports) – not a problem, I don’t care – it says – I just hope you know what you’re doing. And we sure know – just accessing properties that we’ve attached ourselves to the object. We’ll be fine.
SpecRunner.html file in web browser again shows us report from test running – all specifications passing (hopefully!) and everything is green. Cool!
And that’s why dynamic languages are so fun – no need to worry about interfaces, types and everything else when all you need to do is some small hack to make some libraries work in different environments. Pretty clean hack I think in this case. Of course including to many of those is not a good idea. One still needs to follow good practices of development process. But that’s not the point. The point is when you need to do something simple – it is exactly this – simple! All script languages should be like this – and not some weird
C implementations with all kind if limitations and stuff you need to worry about
So that one was simple. I think my code files organization needs some small update for better looking references – but that’s simple. I’m just happy to see everything running OK with so little work required. We will see what’s further on the road. ’till next time!
I’ve recently started working with
CoffeeScript and wanted to do things right. This means writting some tests and generally trying to follow
Code needs to be modular – that’s pretty obvious for anyone who ever worked with something else then tiny “hello world”-like programs. Having 1k Lines of Code in a file is pain. With 5k LoC it seems almost impossible to work effectively. And even more – I definitely like having my tests in separate files than my production code. So I my project structure like this:
For now it seems enough. Spec directory holds test files (aka. specifications). In main directory there are classes and everything else. It will probably change when project will start getting bigger, but for now it’s good. Lets just take a look at files content:
A simple class and test. It doesn’t get any simpler than that, does it? BTW, if you don’t know how the specifications work – take a look at Jasmine tutorial – it’s all pretty easy and nice.
How do I run those tests? Well,
Jasmine says that I should create test running
html file and include required scripts in there. Simple, sure, but – boooring. Who likes going to the browser to see if test are passing? No – I wanted to be able to run them from command line. In future this will make it easy to include them in some
Continuous Integration and what else.
Jasmine-node comes to help! It allows running
Jasmine specifications using
nodeJs. Exactly what I was looking for.
So I installed it:
npm install -g jasmine-node
and tried running the tests:
jasmine-node --coffee ./spec
--coffee parameter indicates that specifications are written using
CoffeeScript, second parameter is simply path to directory containing specifications that needs to be run. After spending some time fighting with this tool (there is a bug that suppresses any error messages when running under
nodeJs 0.10 so it wasn’t notifying me on compilation errors – workaround – try first compiling
spec.coffee files manually if you see that
jasmine-node quit with no error or output at all) it run my tests. And they failed.
Reason for this is pretty obvious – there is no reference for
Ball class in specification. In
C# we would need to add
using statement, but what about
Ball would be defined in different block of code and would not be visible outside of it.
CoffeeScirpt proposes attaching the class to some global variable (like window) or exporting it using
nodeJs exporting mechanism. First solution will work when running in browser. Second when in
nodeJs context. But I want both – tests in
nodeJs and normal code in browser!
In this case there is no other way but to decide on runtime which export mechanism is to be used. And since
root = exports ? this
root.Ball = Ball
CoffeeScript existing operator – it checks if variable is defined (i.e. is not undefined and not null) and returns that variable if defined. If variable does not exist – it returns statement on the right.
this is object which is used to create class definition – in browser it will be
window instance – who would’ve guessed? In second line we assign our class to property on exporting point – how I love dynamic languages!
OK, exporting is covered. But how to import this in specifications? It’s simple since we assume our specifications will be run only from
nodeJs – then we can use
require method and get what we want. Below is final code:
Require returns exports object. To this object we have attached our
Ball class and now we can retrieve it and use it in our code. Re-running
jasmine-node tool proves that everything is OK now – test passes. Problem solved!
What’s left? Well – it won’t work if we will try using normal
jasmine html runner. But I think I have an idea on how to solve this as well – with a little hack, but it should be fine, I hope. We will see how it turned out in next blog post. Take care!