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Agile Software Dev

BDD in 2020

It’s 2020: can we officially declare Behaviour Driven Development (BDD) dead?

How did we get here?

“There is no trap so deadly as the trap you set for yourself.”

Raymond Chandler, Long Goodbye

BDD’s lure was the promised land of collaboration between business and technology defining expected behaviour as executable specifications (automated tests). These automated tests defined our software development processes: outside-in software development, behaviour driven development, acceptance driven test development and specifications by example.

BDD’s trap was a bunch of Cucumber specifications written after the fact that create another layer to automate tests in a browser, hidden away in source code which are seldom, if ever, seen by the business, and either too comprehensive, flaky and expensive, or narrowly focused but lacking in enough detail for a complete executable specification of a system.

Sure BDD tests can drive things besides the browser, but the overhead and complexity of maintaining these outweighs the benefits they serve, especially when there is still a need for more expensive integration/e2e tests anyway.

So what actually works in 2020?

I’ve found this process seems to work really well for modern software development in 2020:

  1. Every new piece of work has a kick-off discussion with the product owner, the tester and the developer(s)
  2. The tester usually facilitates this meeting and aims to produce written lightweight documentation during the discussion containing the following information: background info, scenarios, business rules, examples (edge cases), questions and decisions.
  3. This documentation is enough for development work to begin, and the tester to plan how they’ll test it.
  4. The documentation is updated as work progresses: questions arise and decisions are made (and documented).
  5. The developer(s) is/are responsible for making sure there is automated test coverage for these business rules at the cheapest level of testing, these are typically automated unit and/or automated integration tests. These aren’t written in business readable language, they’re test code alongside production code.
  6. The developer also needs to ensure any existing automated end-to-end (e2e) tests are updated for the work that is happening – CI builds highlight these impacts/failures.
  7. When the feature, or a working part of the feature, is ready for testing the developer and tester do a quick handover/walkthrough making sure what was done is what was discussed.
  8. The tester uses the lightweight documentation as a basis for their testing, but adds extra rigour in testing edge cases/unknowns, other impacted areas, different browsers, performance, and devices and anything else they think could be risky.
  9. Bugs that are found and determined by the product owner to be crucial are fixed immediately, some bugs become “fast follows” which are the next thing to ship. Some bugs aren’t fixed.
  10. The tester gives a walkthrough to the product owner and sometimes UX designer to make sure what’s been done is acceptable – if the feature is new/risky it’s launched to a subset of customers and can be disabled at a flick of a toggle.
  11. When an entirely new feature is added to the system and it’s important enough to warrant an (expensive) automated e2e test – the tester works on adding that in amongst their other work. This isn’t a blocker to release and provides a safety blanket for future changes. This isn’t a comprehensive specification of the system – it’s an e2e automated test that covers a business critical flow over multiple moving parts and again doesn’t need to be business readable.
  12. The specifications/documentation lives on in a wiki page and can be referred back to when testing future changes to this feature, or when support tickets or bugs are found in production.

BDD isn’t working for us, what can I do now?

  1. Make sure you commit to having kick-offs and encourage robust discussion creating lightweight documentation as you go – remove uncertainty and create clarity by making and documenting questions and decisions.
  2. Keep your lightweight specifications up to date as you go – don’t worry about making them executable – let people write automated tests in the way that is the most efficient for them.
  3. Only use automated e2e tests to cover key user flows in the most efficient way – don’t use these to create/maintain comprehensive living documentation.

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