ruby: Adopt .tool-versions and standardise script/setup for ruby

ruby/.tool-versions

@@ -0,0 +1 @@
+ruby 3.4

ruby/README.md

@@ -1,17 +1,32 @@
 # Ruby
 
-Pairing test starter project for Ruby with rspec for testing.
+Skeleton project for Ruby.
+
+## Prerequisites
+
+The toolchain this project needs is declared in [`.tool-versions`](./.tool-versions):
+
+```
+ruby 3.4
+```
+
+Install those however you prefer, as long as they end up on your `PATH`. The quickest route is
+[mise](https://mise.jdx.dev/), which reads the file for you:
+
+```sh
+mise install
+```
 
 ## Usage
-- `./script/setup` to install dependencies
+- `./script/setup` to fetch dependencies
 - `./script/test` to run the tests
-- `./script/start` to run the code
+- `./script/start` to run the app
 - `./script/console` for an interactive prompt
 
 ## Structure
-- Code located in [pairing_test.rb](./lib/pairing_test.rb)
-- Tests located in [pairing_test_spec.rb](./spec/pairing_test_spec.rb)
+- Code located in [`pairing_test.rb`](./lib/pairing_test.rb)
+- Tests located in [`pairing_test_spec.rb`](./spec/pairing_test_spec.rb)
 
 `lib` has been added to the `require` path so all imports inside the `lib` directory must be relative to this, e.g. `require "pairing_test/version"`.
 
-However, you're free to organise your code as you like. 
+However, you're free to organise your code as you like.

ruby/script/setup

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
+
 set -euo pipefail
-IFS=$'\n\t'
-set -vx
 
-gem install bundler
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
 bundle install

ruby/script/test

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
-set -e
+set -euo pipefail
 
-rake spec
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+
+bundle exec rake spec