Tuesday, 27 February 2018

Verification of Sitecore Helix Architecture via a Fitness Function

Recently I've been reading - and recommend - the book Building Evolutionary Architectures by by Neal Ford,‎ Rebecca Parsons and Patrick Kua, where they discuss the concept of a fitness function. The idea here is that, as well as implementing the business requirements, a solution will also need to address certain non-functional concerns, such as security, performance, reliability and maintainability. Some of these can be measured or validated, and therefore tested, and ideally, tested in an automated way.

Within a Sitecore project I'm working on, we are adhering to the Helix principles that in part addresses the organisation of projects with a Visual Studio solution. You end up with many individual projects, each within a layer - foundation, feature and project.

  • The foundation layer is considered the highest level and most stable. Projects within this layer may have dependencies on each other, but not on any at the lower levels.
  • Feature layer projects are intended to be cohesive and swappable, in the sense that they can be reused across solutions with minimal impact on other projects. They can depend on foundation projects, but not any other feature ones, nor any at the lowest level.
    With a couple of caveats. In our solution, some features are themselves broken into one or more projects, which we call sub-features. It's OK and necessary that they have dependencies between them. We also of course allow test projects to reference their associated feature project.
  • The lowest level is the project layer, containing one (or more) projects representing the website(s) themselves. They can depend on feature and foundation projects, but not on each other.

Ensuring developers adhere to this and don't create inappropriate project references is an ideal job for an automated fitness function, which I've put together as a unit test using MSTest. There's a strict naming convention we follow with the projects within the solution and I'm leaning on that in order to write the test - of the form SolutionName.LayerName.ProjectName, e.g. MySolution.Foundation.Analytics.

The code for this can be found in the following gist:

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