go-internal

The Go team's emphasis on tooling in the service of software engineering is a boon to human and agentic development alike. Give yourself and your agents great tools. An example from one of my recent projects: https://github.com/verdverm/gmd/blob/main/Makefile (give agents simple "tool calls" instead of needing to divine the correct args/flags every time, essentially invocable agents.md content) One of the interesting things to call out from this is using build tags for testing { unit, coverage, recorded, real api }, with the buffet allowing the agent to iterate faster and more targeted. I tend to run the linting and coverage in a new session, have a report generated, and then another fresh session to start dealing with gaps. Another super cool testing tool in the Go internal source is `testscript`. Roger Peppe extracted a number of those

I believe go tooling is one of the top loved features among gophers, in particular gofmt. The best part is that all those command line utilities are also available for import. I've used them to create a license checker by walking the dep tree in code. There are also a ton of gems in the `./internal` directories, Roger Peppe has extracted them for reuse here: https://github.com/rogpeppe/go-internal

txtar is used in the testsuite package to make writing CLI (blackbox) tests really easy. It adds a header section for the steps to run and comparisons to make. Often you compare actual output with golden data. (https://github.com/golang/go/tree/master/src/cmd/go/testdata...) The tools have been extracted and made installable from here: https://github.com/rogpeppe/go-internal/tree/master/cmd This is really handy for any project to have people submit reproducers as a single file anyone can run. These tools make it so you can transform between txtar and files on disk, and then run the txtar (testscript) as a test or directory of tests. I have built them into my hof tool, "hof run [--mode test] file.txtar" so you run them as either test files or multifile scripts. The second option is handy if you want to eject a file onto the filesystem with

The Go compiler has a really interesting, black box testing tool called "testscript" You can find an extracted, installable version here: https://github.com/rogpeppe/go-internal/tree/master/cmd/test... For test cases, I would look to libraries in any language that has them in an easy to copy format

No idea if the technique was original, it’s been too long, but I wrote about it on the Cloudflare blog in 2016. https://blog.cloudflare.com/go-coverage-with-external-tests/ Anyway, very happy to see the team ship first class support for it. It immediately made coverage support in testscript much more natural, too. https://github.com/rogpeppe/go-internal/pull/201

Highly recommend Go, especially for that realm. Building something else that already exists can provide a good roadmap and reference for how things are / can be done. You could build a server, but I'd personally find something like https://nats.io (messaging) https://fission.io (serverless) or https://redis.io (cache) more interesting. You might also look at the Kubernetes ecosystem. Building a tool or service that can interact with the API can lead to new opportunities (people hiring specifically for operator experience). I work on a code generation tool (https://github.com/hofstadter-io/hof) and https://github.com/cuelang/cue Go's source is also pretty interesting and full of great things (https://github.com/golang/go). Here are some of the internals pulled out: https://github.com/rogpeppe/go-internal