Navigating Babylon Part II

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How to Introduce DomainSpeak in Testing

First, let’s start with a quick overview of the problem I discussed in Navigating Babylon Part I. Microservices create efficiencies in development in a world dependent on remote work environments and teams. Unfortunately, the separation of workers and teams results in the tendency for microservices to encourage the development of multiple languages or dialects that obfuscate communication and further complicating testing. We have our anti-corruption layer and we don’t want to pollute our code by spilling in sub-system language.

A Domain-specific Vocabulary for Testing: DomainSpeak

There is, however, a pragmatic solution: we can build on the anti-corruption layer by creating tests in a specific language that has been created to clearly describe business concepts. We can and should create DomainSpeak, a domain-specific vocabulary or language, to be used for testing. Once we publish information in this language it can be shared across microservices and thus influence the workflow. Periodically, as is done in the English language, we may need to improve definitions of certain vocabulary, by re-defining usage and disseminating it widely, thus influence its meaning.

How will this DomainSpeak improve testing?

For integration tests, all the different dialects should not permeate your integration tests. You need to be very clear that a word can only have a single meaning. This requires a two-part process:

  1. You need to verify that you are not inconsistently naming anything inside an actual test; and,
  2. You need to do translations in an anti-corruption layer so everything inside is consistent.

What does DomainSpeak look like in a practical sense?

When you consider how brands influence pop culture, it is through language.

In the business world, marketing professionals use domain specific languages to create a brand vocabulary or a BrandSpeak. All major and influential brands and even smaller yet influential brands have a specific vocabulary, with specific definitions and meanings, to communicate their brand to the public. All communications materials are integrated into this system.

Brand specific, intentional vocabulary, has the ability to invade and permeate. Many people are completely unaware that it was a DeBeers commercial in the 1940s that created the cultural tradition “a diamond is forever.” Other examples, “Don’t mess with Texas” came from an anti-litter campaign and although we know it’s a marketing ploy, just about everyone is on board with the idea that “What happens in Vegas, stays in Vegas.” On an international level, if you order a “coke” you will most likely get a carbonated beverage, but you won’t necessarily get a Coca-cola.

As I referenced in my first discussion on Navigating Babylon, I recommend implementing a mapping layer between the microservices and the test cases. Next, when deciding to address the language used, we take it a step further. Now focus in on the language or the DomainSpeak and how this domain-specific vocabulary improves the associated output of the test cases. This means that for example, a Customer, a User, and a Client all have specific meanings and that they cannot be interchanged.

What is the process to create this language?

The initial process is an exploratory step. To create your own DomainSpeak your testing department will need to communicate regularly with the business owners and developers. Their goal will not be to dictate what words the business owners and developers use, but to learn what words already have meanings and to document these usages. The more your communicate, recognize and document adopted meanings, the more you will discover how, where and why meanings differentiate.

For instance, the business may see a Customer as a User with an active subscription, whereas a microservice might use the words interchangeably as they do not have the concept of a subscription. You will also notice that sometimes situations may give rise to conflicting meanings. A developer may have picked up the word “Client” from a third party API he integrated with for “User,” whereas the business may use “Client” for a specific construct in a billing submodule for “customers of their customer.” In such situations, to avoid confusion and broken stuff, you will need to specify which definition is to be used and possibly introduce a new concept or word to account for the narrowing of the definition. Perhaps the “customers of their customer” will now be a “vendee” instead of a “client.” Don’t dismay if there is not an existing word that accurately matches your concept, you can always create a new word or make a composite word to meet your needs.

Indeed, by being consistent and by distributing your use of language to a wide audience you can introduce new words and shape the meaning of existing words. This means that your tests have to be very close to a formal and structured form of English. This can be accomplished by using Aspect-oriented testing or by creating fluid API wrappers on top of the microservices. Aspect-oriented testing would look like this (cucumber syntax):

Given a User
When the user adds a Subscriptions
Then User is a Customer
Whereas a fluid API would be something like this (C# syntax)
User user1 = UserManager.CreateNewUser();
SubscriptionManager.AddNewSubscriptionFor(user1);
Assert(UserManage.Get(user1).IsCustomer());

This creates a lot of focus on syntactic sugar* and writing code behind the scenes to ensure that your code incorporates your business logic (your test) and looks the way you want it to. Every language has their own way to solve this challenge. Even in C, you could use macros to take a pseudo code and turn it into something that would compile, and chances are that your results would be far superior to that of your current language usage.

For my uses, the cucumber syntax, with a side of extra syntactic sugar that allows me to define variables, is very effective. (I will get into this in more detail another day.) Whichever language you use, keep in mind that the goal of creating a DomainSpeak vocabulary is not to make your code look pretty, but rather to ensure that your code communicates clearly to the business and developers and that meanings are defined with precise and consistent language.

The End Goal is Efficient Quality Assurance

The goal, after all, is to improve productivity and deliver a quality product. Clear communication will not only benefit your team internally, it will also influence other teams. By communicating your results in consistently clear and concise language to a wide audience, you will influence their behavior. You will be able to efficiently respond to questions along the lines of “we use ‘customer’ for all our ‘users.’” You will also be able to easily define and answer where the rule may not hold and why you use the word you use. Again, the goal is not to dictate to folks what words to use, but to explain the meanings of words and to encourage consistent usage. Adoption will follow slowly, and over time usage will become a matter of habit. Over time services will be rewritten and you should be able to delete a few lines from your anti-corruption layer every time one gets rewritten.

*syntactic sugar allows you to do something more esthetically, but not in a necessarily new way. Different ways of saying the same thing. Just looks different. Not important because it’s not new, but significant because it makes things more readable and understandable. Clean up language/clearer code and therefore easier to find a bug.

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