Create a Dockerfile:
FROM ruby:2.6
WORKDIR /app
COPY Gemfile ./
RUN bundle install
COPY . /app
A handy Makefile:
PREFIX = docker run -v "$(shell pwd)":/app --rm --name appname imagename
build:
docker build -t imagename .
test: build
$(PREFIX) bundle exec rspec spec
Create a Gemfile and add some gems to it:
bundle init
bundle add rspec
And you can now create the following directory structure in your local folder
lib/my_class.rb
spec/my_class_spec.rb
Write some specs and run them with:
make test
Huzzah!