If you have ever seen the 1976 movie ‘All the President’s Men’ you may remember the phrase “follow the money.” The idea behind this is that political corruption could be exposed merely by looking at financial transfers between parties. In testing, I like to give a slight tweak on this phrase and say, ‘follow the revenue.’ What does this mean? Plainly, we should focus most of our testing efforts in the ways that we will see the most positive return.

Flaky tests are like meme stocks — many people have them, but no one knows what to do with them. Today, we will change that by diving into some common causes and, more importantly, solutions for flickering tests in Elixir. Elixir has many great primitives that let us run tests asynchronously, including immutable data, lightweight processes, and the Ecto SQL sandbox. Running tests asynchronously can greatly speed up your test suite, but can also increase the chance of flaky tests.

In software development, there’s almost nothing more stressful than a hotfix—when a customer reports a bug that’s so severe everyone stops what they’re doing (no matter what time of day) to fix the bug. Hotfixes interrupt workflows and seem to always happen at the worst times. Often, a series of hotfixes will drive software teams to ask themselves: why isn’t our QA team catching these, and how can we improve QA?