A Ratio between Tests

During one of my recent projects I was considering the ratio between the checks and the tests – that is the ratio between those tests, that are primarily simple binary confirmations, and those tests that are more tacit questions. This blog is about my considerations on the idea/experiment/model.

First I observed, that we have a range of different items in our requirements – some of them are [actual copy of the current specification]:

Binary Confirmations

• It must be possible to add a customer ticket reference
• It must be possible to copy the ticket number

Tacit Questions

• You must be able to navigate displayed lists easily
• It must be easy to compare work log and audit log

You could argue that they need refinement, more testability and less “easy“. But this is what we have to work with for now. Even if we had all the time in the world (we don’t) – we would not be able to write all of the requirements in a perfect form (if such a form exists).

As the system under test is a commercial standard system, some of the requirements are even given as “Out of the Box”, we will probably not even be testing those explicitly. Our coverage criteria is not ALL OF THEM.

Ordering the tests

It is a deliberate experiment from my side to divide the requirements (and hence the tests) into the piles of Closed and Open Questions. Perhaps there is even three piles – Rapid Software Testing has: human checking, machine checking and human/machine checking , Wardley has Pioneers, Settlers and Town Planners. Perhaps the Rule of Three applies here too.. perhaps it’s an continuum … let’s see.

Perhaps it’s a continuum

As part of the requirement workshops I will label the requirements and align with the stakeholders to get the expectations right – with the help of a few friends. This a context/project based “operationalization“.

I wrote about this ratio on my blog post around the Test Automation Pyramid, as I will use the labels to automate the confirmations (and only the confirmations). The assumption is, that there are significantly more of the binary requirements tested by machine checking – and more human tested tacit questions. If we can get all the tedious tasks automated – that is the really the end goal.

Automate all the things that should be automated

Alan Page

Every project/context will have it’s own ratio, depending on a range of factors. Saying there should always be more of one type than the other would not hold. As the above project is the configuration and implementation of a standard commercial business software package (like SAP, SalesForce etc), my expectation is that most of the requirements are binary. Also considering that this project is heavy on the right hand side of the Wardley Map scale of evolution.

It’s a Reduction in Context

I am well aware that the two/three piles are an approximation / reduction. Especially when looking at the “binary” requirements and “only” testing these by confirmation. They could as easily be explored to find further unknown unknowns. If we prioritize to do so – it all about our choice of risk.

It is also an limitation as “perfect testing” should consist of both testing and checking. I factor this into the test strategy, by insisting that all of the requirements are tested both explicitly and implicitly. First of all most of our binary requirements are on the configuration and customization of the out-of-the-box software solution. So when the subject matter experts are performing the testing of the business flows, they are also evaluating the configuration and customization. And I do want them to spot when something is odd

The binary configuration is ok, but human know-how tells us otherwise.

Ultimately I want to use the experts to do the thinking and the machines to do the both the confirmations and the tedious tasks.