If you don’t know what Pester is, it’s a test framework for PowerShell. In the simplest explanation, using their Domain-Specific Language (DSL) you describe how things should look. If all looks good it returns output in green and if it doesn’t you get red output. There are a lot of great use cases for Pester, like using it to ensure your code does what it’s supposed to, using it to validate your SQL Server environment (dbachecks), or in this example using it to make sure your demos are setup and ready to go.
When I’m preparing for a presentation I go through the demos over and over again, so it’s easy to accidentally leave things in a state that will cause issues when I go to do my demos in the presentation. If you’re creating a table, for example, during the demo and you already created it practicing and then forgot to drop it, the demo gods will strike and it’ll fail when it matters most! A simple Pester test to check whether the table exists will solve this issue.
Even if you aren’t giving talks in public (or inside your company), Pester is a useful tool for ensuring that the thing you expect to be the case actually is the case.