To display version information about .NET Core on versionsof.net, I had to decode the releases.json files in the dotnet/core repo. Not a big problem, you'd think. These are just JSON files, how hard can it be? That's fair, but the schema, nor the data of these files turned out to be really consistent. To help with this, I created the NetCore.Versions.Checks GitHub app that checks these files on every commit.
The schema I use is available on NuGet as a package containing the schema expressed in F# records and decoders for use with Thoth.Json.Net. One of the biggest benefits of using Thoth.Json are its crystal clear error messages, explaining exactly what is wrong with the provided JSON files. This was really helpful for building the GitHub app.
To help with the consistency of the releases.json files, I created a GitHub app that runs a set of checks on every commit. It is implemented as a Giraffe web app, running on the free Azure App Service tier. To execute the checks, I created a small testing framework with support for tree structured tests on data objects, using the excellent Unquote library to provide clear error messages.