The notion that Test Coverage alone can provide an adequate metric for determining how well a particular piece of code, or worse, an entire codebase, is being tested has always troubled me as, in my experience, this can be a very misleading assumption.

Like so many of my previous themes, with Test Coverage context trully is key as, relying on a predetermined percentage threshold as a true measure of successful testing fails to take into account the numerous factors involved. For example, the preceived thoroughness of a systems tests can easily be increased – beit mistakenly or intentionally – by testing parts of the system which could be considered irrelevant; such as getters, setters and the like.

Personally, I prefer (and advocate) focusing first on testing the most critical behaviors and state of a particular piece of code. The tests should not be limited to just testing the expected cases but also, and of equal importance, the testing of exceptional and negative tests.

I could go on about this in great detail however I recently came across a really good post from googletesting (which I found via Mike Labriola) which I think pretty much sums it up.

Often I come across what I like to call “Misplaced Code”, that is, code which should be refactored to a specific, independent concern rather than mistakenly being defined in an incorrect context.

For instance, consider the following example to get a better idea of what I mean:

Taking the above example into a broader context, it is quite common to see code such as this scattered throughout a codebase; particularly in the context of view concerns. At best this could become hard to maintain and, at worst, it will result in unexpected bugs down the road. In most cases (as in the above example) the actual code itself is not necessarily bad, however it is the context in which it is placed which is what I would like to highlight as it will almost certainly cause technical debt to some extent.

Considering the above example, should code such as this become redundantly implemented throughout a codebase it is quite easy to see how it can become a maintenance issue as, something as simple as a change to a hostname would require multiple refactorings. A much more appropriate solution would be to encapsulate this logic within a specific class whose purpose is to provide a facility from which this information can be determined. In this manner unnecessary redundancy would be eliminated (as well as risk) and valuable development time would be regained as the code would need only be tested and written once – in one place.

So again, using the above example, this could be refactored to a specific API and client code would leverage the API as in the following:

This may appear quite straightforward, however, I have seen examples (this one in particular) in numerous projects over the years and it is worth pointing out. Always take the context to which code is placed into consideration and you will reap the maintenance benefits in the long run.

Back in September 2008 I published a post on Class Annotations in Flex, through which I provided an API allowing for a unified approach for working with AS3 metadata. Just recently I intended to use the Metadata API in a Flex 4 project when I noticed it no longer seemed to work as expected. After a bit of debugging, I realized the bug appeared to be related to changes in the result returned from describeType; specifically, the addition of the “__go_to_definition_help” metadata. Considering the Metadata API leverages describeType in order to introspect metadata definitions, this made sense.

I made some simple modifications to the API to work with the new metadata returned from describeType and this resolved the issue. While I was in the process I also refactored operations to return Vectors as opposed to ArrayCollections, as was the case in the original design; effectively optimizing the API for Flex 4 (as well as Flex SDK 3.4).

You can download the source/tests/swc/docs dist here; all of which will be available soon via SVN and a public Maven repository, more on that once it’s ready.

A week or so prior to MAX, the Cairngorm committee had a rather interesting discussion, during which Alex outlined what the team at Adobe Technical Services had been considering for Cairngorm 3. The meeting was focused on providing everyone with an overview of the collective ideas which Adobe had been gathering internally for some time now, and to also inquire feedback prior to the public announcement of Cairngorm 3.

Prior to the meeting I had anticipated the discussion would be based around a few new patterns and best practices which are currently being advocated, and possibly some additional libraries which help to address recent challenges in RIA development. However, what we discussed was actually quite different – in a good way.

As you are probably aware by now, Cairngorm 3 is focused around tried and tested best practices and guidelines which aid Flex developers in providing solutions to their day to day RIA challenges. These guidelines are primarily based upon that which has been realized by Adobe Technical Services, and also from the Flex community at large. Teams can leverage these guidelines where applicable to help deliver successful RIAs using frameworks of their choosing. While there may be specific frameworks and libraries recommended in Cairngorm 3, these are just that – recommendations. There is generally a framework agnostic approach which I must emphasize is highly preferable to that of suggesting one framework over another. This is precisely what I think is needed in the Flex community, for there is rarely a one size fits all approach to software architecture, especially in terms of specific framework implementations. This is a pretty easy concept to comprehend, as, what works for one team, in one context, may not always be appropriate for another team, or in another context.

Cairngorm 3 is a step forward towards what (IMHO) should be a general consensus in the Flex community at large; there are many existing frameworks out there which help address specific problems, with each providing unique qualities and solutions in their own right. This is the kind of thought leadership which helps a community progress and grow; it should be encouraged, as allowing for the shared knowledge of fundamental design principles and guidelines is something which provides value to all Flex developers, regardless of which framework they happen to prefer.

If there is one suggestion I would propose, it would be to have an entirely new name for these collections of best practices, guidelines and general Flex specific solutions. Personally, I would like to see the name Cairngorm (which, after all these years, I still pronounce as Care-in-gorm) refer to the original MVC framework, i.e. the framework implementation itself, as keeping the name the same while undergoing a different direction is bound to cause confusion to some extent. Whatever the new name would be is insignificant as long as the original name of Cairngorm applied to that of the actual framework implementation. This would perhaps be more intuitive as it would allow for the name Cairngorm to be used to describe a concrete framework as a potential solution, just as one could describe other frameworks; e.g. Spring ActionScript, Mate, Swiz, Parsley, Penne, Model-Glue, PureMVC, Flicc etc.

Most importantly, however, is the prospect of choice, as choice is always a good thing. Moreover, an initiative being lead by Adobe in this area sends a very good message to the Flex community as a whole. I happen to leverage a number of different frameworks and patterns which address different problems. As new problems arise, I employ new solutions where existing solutions may not suffice, or develop custom solutions where none are currently available; never blindly choosing one solution over another. However, in every case, there are typically some basic, fundamental guidelines which hold true and can be followed to help drive a design in the right direction. Regular readers of this blog have probably noticed that the basis of the majority of my posts are heavily rooted within these fundamental design principles, as it is from these fundamental design principles and guidelines that developers can utilize the frameworks which work best for them in order to and meet their specific challenges.

Essentially, Software Architecture is all about managing complexity, and there are many fundamental patterns and guidelines which can help developers mange this complexity. The specific framework implementations are of less concern, for it is the understanding of these patterns and principles – and more importantly, when to apply them, which will ultimately drive the decisions to leverage a one framework over another. In my experience, I have found that the only constant in software architecture is that a pragmatic approach should be taken whenever possible, whereby context is always key, and simplicity is favored as much as possible. Cairngorm 3, I feel, is a nice illustration of this principle.