Showing posts with label Mockbox. Show all posts
Showing posts with label Mockbox. Show all posts

Sunday 19 April 2015

PHP: unit testing private methods (a bit of reflection)

Yes, I still do PHP as well as Lucee. Well, indeed, I don't do Lucee, I just seem to "invest" my time blogging about it. I am very much doing PHP all day every day again now.

Recently I revisited the notion of unit testing private methods. I realise a lot of people poopoo this notion as one is only supposed to unit test the interface, so only public methods. However when doing TDD, one needs to maintain one's private methods too, so this means one needs to test the behaviour of the change before making it.

Some argue these days that one should not have private methods: having them suggests bad class composition and a private method should be a public method of another class. I can see where they're coming from, but I also suspect the person deciding this was a Java developer and revels in the theory of OO put into practice, rather than... you know... getting shit done. I am in the "getting shit done" camp. I see no benefit in making classes for the sake of it, and I also like the idea of having code as close as possible to where it'll be used. So private helper methods have their place. And they need to be tested whilst being developed.

Others make the very good point that what actually needs testing is the nature of the impact on the result of the public method is what's important, so a private method ought to be tested "by proxy": call the public method, give it inputs that will invoke the to-be-developed new behaviour, and don't care - at test level - where the code happens to be. I have come to appreciate this idea, and it's how we approach a lot of our testing now.

One hitch with this is sometimes it's difficult to only hit the new functionality without also having to horse around appeasing other bits of functionality on the way through. Mocking makes this a lot easier, but not everything can be mocked, and even mocking stuff can be time and effort consuming. I guess if our code was perfect we'd not have this issue so much, but it's not (we're not), so we need to deal with that reality.

Sometimes it's just bloody easier to test a private method.

Back in my CFML days this was piss-easy. MockBox comes with a method makePublic(), which simply makes a private method public. It achieves this by injecting a proxy into the object under test which is public, and this wraps a call to the private method. One then calls that proxy in one's test.

Using makePublic() is as easy as:

mockbox.makePublic(object, "methodName");

Then continue to call methodName as per usual in one's tests. Cool.

This ain't so easy in PHP. One cannot just inject proxy functions into one's methods. However one can use reflection to make changes to an object's existing methods, including its access restrictions.

So what I set out to do was to make my own makePublic() method.

I arrived at this:

private function makePublic($object, $method){
    $reflectedMethod = new \ReflectionMethod($object, $method);
    return $reflectedMethod;        

(it's private as it's just inline in my test class, the entire code for which can be seen here: SomeClassTest.php SomeClass.php).

This is simple enough. However actually using it is inelegant compared to the MockBox approach:

@covers isIndexedArray
function testIsIndexedArray(){
    $testValue = [53,59,61];
    $exposedMethod = $this->makePublic($this->testObject, 'isIndexedArray');
    $actual = $exposedMethod->invoke($this->testObject, $testValue);

That's no so clear.

So I decided to abandon that approach, instead coming up with this method:

private function executePrivateMethod($object, $method, $arguments){
    $reflectedMethod = new \ReflectionMethod($object, $method);

    $result = $reflectedMethod->invoke($object, ...$arguments);
    return $result;        

This does the same thing, but it looks far more understandable in the calling code:

@covers isIndexedArray

function testIsIndexedArray_withAssociativeArray(){
    $testValue = ['a'=>67,'b'=>71,'c'=>73];

    $actual = $this->executePrivateMethod($this->testObject, 'isIndexedArray', [$testValue]);

It's really clear what executePrivateMethod does, I reckon.

I'mm going to show this to the lads at work tomorrow, and see what they think. Note: my position in general will be to test via the public interface, but in those situations where this is going to be a lot of work, or make the testing unclear, hopefully we can use this instead.



Monday 30 December 2013

Unit Testing / TDD: not testing stuff

It's about bloody time I got back to this series on TDD and unit testing. I've already got the next few articles semi-planned in my head: topic, if not content. I have to say I am not in the most inspired writing mood today, and the words aren't exactly flowing from fingers through keyboard to screen - this is the third attempt at this paragraph - but we'll see how I go.

To find inspiration and to free up the fingers a bit, I'm at my local pub in Merlin Park in Galway, which - today - has shown its true colours as a football pub (to you Americans, that's "soccer". To me, it's "shite"). I've tried to like football, but it all just seems too effeminate to me. The place is chock-full of colours-wearing lads yelling at the screen. Either for or against one of Chelsea or Liverpool (the former lead 2-1 at half time). It's not conducive to writing, but the Guinness next to me will be.

I'll not list the previous articles in the series as it will take up too much room. They're all tagged with "TDD" and "unit testing" though.

On with the show...

Tuesday 23 July 2013

Two things: I'm thick; and one cannot use a Mockbox mocked method as a callback

And to think someone said on Twitter the other day that I'm one of those people who are never wrong (the subtext being "actually you are, but just will never admit it"). Well here's an example of me being wrong, happily admitting it, and admitting to being a bit stupid to boot.

Thursday 11 July 2013

Weird issue with MockBox and interfaces: issue identified

A coupla days back I wrote a vague article "Weird issue with Mockbox and interfaces", which detailed some weirdness I was seeing with using Mockbox to mock methods in CFCs which implement an interface.  The short version is that on the first use of a method mocked this way, I was getting this error:

coldfusion.runtime.InterfaceRuntimeExceptions$ArgumentsMistmatchException: Function argument mismatch.[etc]

However if one just re-ran the test, the problem went away. In fact it was only the first usage of the mocked method after ColdFusion was started that caused the problem. Subsequent runs: all good. Restart CF: problem. This is on ColdFusion 9 & 10, but not Railo.

Tuesday 9 July 2013

Weird issue with Mockbox and interfaces

This is not gonna be a very well-realised article, as it's posing a question that I've not really been able to flesh out yet.

Thursday 4 July 2013

Repro case for "contains" pseudo-reserved-word interfering with Mockbox

This is mostly for Brad Wood, but it might be of passable interest to others, so I'll plonk it here.

Yesterday's article discussed how contains is kind of a reserved word, but kind of not in ColdFusion (it's just not in Railo). I observed to Brad that this actually bites us on the bum with Mockbox, and he asked for more info, so here it is.

Basically we use a caching system which has a method "contains" which checks to see if there's an item with a given key already in the cache, before trying to fetch it. We've actually since revised this approach, but we have some legacy code still using methods called "contains". So we need to unit test them, and indeed their responses play a part in other methods we test. When testing these other methods which use the caching system, we mock-out the cache, and the methods within it, and we use Mockbox to do this. Mockbox is cool, btw. You should be using it if yer not already.

We're still using Mockbox 1.3 (more about why further down), and it is impossible to directly mock a method called contains using Mockbox. We've worked around this, but it took a bloody long time to work out what the hell was going on, and that there was working-around to do.