A fellow ThoughtWorker James Crisp recently wrote an interesting article about his take on an automated test pyramid.
Some of the terminology he used was interesting, which is what I believe led to some questioning comments and a follow up article by another fellow ThoughtWorker, Dean Cornish, who stated the pyramid “oversimplifies a complex problem of how many tests you need to reach a point of feeling satisfied about your test coverage“.
I believe that one of the most unclear areas of James’s pyramid is the use of the term Acceptance tests, which James equates to roughly 10% of the automated test suite. One commenter stated these should instead be called functional tests, but as James points out, aren’t all tests functional in nature? I would also argue that all tests are about acceptance (to different people), so I would rephrase the term to express what is being tested, which in his case is the GUI.
The other fundamental issue I see with James testing pyramid is that it is missing exploratory/session based testing. The only mention of exploratory testing is when James states ‘if defects come to light from exploratory testing, then discover how they slipped through the testing net’, but I feel this could be better represented on the pyramid. Exploratory, or session based testing, ensures confidence in the automated tests that are being developed and run. Without it, an automated testing strategy is fundamentally flawed. That’s why I include it in my automated testing pyramid as the Eye of Providence (I originally got the ‘eye’ idea from another ThoughtWorker Darren Smith).
Show me the Pyramid
Without further ado, here’s my automated test pyramid. It shows what the automated tests use to test: being the GUI, APIs, Integration Points, Components & Units. I’ve put dotted lines between components, integration points and APIs, as these are similar and it might be a case of testing not all of these.
Another way of looking at this, is looking at the intention of the tests. Manual exploratory tests and automated GUI tests are business facing, in that they strive to answer the question: “are we building the right system?”. Unit, integration and component tests are technology facing, in that they strive to answer the question: “are we building the system right?”. So, another version of the automated testing pyramid could simply plot these two styles of tests on the pyramid, showing that you’ll need more technology facing than business facing automated tests, as the business facing tests are more difficult to maintain.
By removing the term acceptance, and showing what the automated tests test, I believe the first automated test pyramid shows a solid approach to automated testing. Acceptance tests and functional tests can be anywhere in the pyramid, but you should limit your GUI tests, often by increasing your unit test coverage.
The second pyramid is another way to view the intention of the tests, but I believe both resolve most of the issues Dean has with James’s pyramid. Additionally they both include manual session based testing, a key ingredient in an automated test strategy that should be shown on the pyramid so it is not forgotton.
I welcome your feedback.