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Local development with devenv

Contributing to Rails Event Store doesn't require hand-installing Ruby (rbenv/rvm/asdf), Postgres, MySQL or Redis on your machine. This repository ships a devenv configuration (devenv.nix / devenv.yaml) that provisions the whole toolchain — the same Ruby CI runs on, plus databases on the exact ports the CI matrix uses.

This builds on the Nix tooling the project already relies on: CI runs the database-backed suites inside nix-shell using the ephemeral database definitions under support/nix/, and pushes build artifacts to the railseventstore Cachix cache. devenv is the local-development front end to that same world.

As everywhere else in this repo, make stays the entry point — devenv only provides the environment the existing make targets run in.

One-time setup​

Install Nix and devenv. Then, from the repository root:

devenv shell

The first run builds/downloads the toolchain (Cachix makes this fast). You land in a shell with the right Ruby, bundler and native libraries for the pg, mysql2 and sqlite3 gems.

Databases​

Start the databases (Postgres 14 + 18, MySQL 8.4, Redis) as background processes:

devenv up

They listen on the same host/port pairs as support/ci/generate, so a DATABASE_URL copied from any CI matrix cell works verbatim:

EngineDATABASE_URL
Postgres 14postgres://postgres:secret@localhost:10014/rails_event_store
Postgres 18postgres://postgres:secret@localhost:10018/rails_event_store
MySQL 8.4mysql2://root:secret@127.0.0.1:10084/rails_event_store
MySQL 9.7mysql2://root:secret@127.0.0.1:10097/rails_event_store
Redis$REDIS_URL (unix socket, exported in the shell)

MySQL 9.7 (CI's mysql_9_7) is the one version nixpkgs can't provide (no 9.x build), so it runs from a mysql:9.7 container instead of a native process. It starts automatically when a docker-compatible CLI (Docker, OrbStack, or an Apple container docker shim) is on PATH; without one, devenv up simply skips it and everything else still works natively.

Running the suites​

Inside the devenv shell, use the regular make targets:

make test-ruby_event_store                 # no database needed
make test-ruby_event_store-active_record   # against Postgres 18 by default

To reproduce a specific CI matrix cell, use res-cell, which maps a short database name to the CI DATABASE_URL and sets DATA_TYPE for you:

res-cell pg14 jsonb make test-ruby_event_store-active_record

Databases are sqlite, pg14, pg18, mysql84, mysql97. Or set the environment variables by hand if you prefer:

DATABASE_URL=postgres://postgres:secret@localhost:10014/rails_event_store \
  DATA_TYPE=jsonb make test-ruby_event_store-active_record

Mutation testing works the same way:

make mutate-ruby_event_store-active_record

Other Ruby versions​

The shell's default Ruby is 4.0 (CI's primary cell). To reproduce a 3.3 or 3.4 cell, prefix the command — each version keeps its own gem home so native extensions never clash:

res-ruby-3.4 make test-ruby_event_store-active_record

It composes with res-cell to pin both axes at once:

res-ruby-3.4 res-cell pg14 jsonb make test-ruby_event_store-active_record

Browser demo​

make -C ruby_event_store-browser dev

Serves the standalone browser, seeded with sample events, at http://localhost:9393.

CI coverage​

.github/workflows/devenv_setup_test.yml boots the databases through devenv and runs a database-backed and a database-less suite on every change to devenv.nix / devenv.yaml, so this setup can't silently rot.