An interactive Ruby on Rails 5 and Test-Driven Development tutorial using GitHub and Travis CI for automation
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README.md

SWT2 2018/19 - Introductory Exercise

This is an interactive Ruby on Rails 5 exercise, based partly on the "Getting Started with Rails" guide. Interactivity is provided by opening issues in the GitHub issue tracker (through a CI server) that contain instructions on what tasks to tackle next.

We prepared an application stub of an academic paper management system for you that has a failing test case.

Follow these steps to complete the software and the exercise:

1) Set up your repository

  • Log-in to Travis CI and enable automatic builds for your exercise repository

  • Ensure that the issue tracker of the GitHub repository is active. This can be done in the repository's "Settings" tab on the GitHub website.

drawing

2) Set up local development environment

  • Clone the repository to your local machine

Option 1: Local setup

  • Change into the newly created directoy
  • Inside the directory, check the used Ruby version using ruby --version. It should be 2.5.0. Other Ruby versions might work, but this is the one that was tested.
  • If the correct Ruby version is not used, install a ruby version manager, for example rbenv using the instructions for rbenv installation and ruby-build installation.
    • WARNING: If you already have the Ruby version manager RVM installed, please use that or uninstall it prior to rbenv installation, as the two version managers are incompatible.
  • Install Ruby version 2.5.0 with rbenv install 2.5.0 (this might take a few minutes, as Ruby is being compiled)
  • The .ruby_version file in the repository instructs the ruby version manager to use the correct version.

Option 2: Use a Virtual Machine

  • Install Virtualbox (the VM provider) and Vagrant (to manage VMs) for your platform.
  • Run these commands in the root directory of your cloned repository to download and the prepare the VM image:
vagrant up # download the image and start the VM
vagrant ssh # connect via ssh
cd hpi-swt2
mkdir -p "$(rbenv root)"/plugins && git clone https://github.com/rbenv/ruby-build.git "$(rbenv root)"/plugins/ruby-build
rbenv install 2.5.0 #install current ruby
ruby --version # check that 2.5.0 is being used
bundle install # install dependencies
exit # restarting the session for changes to take effect
  • To start the development server:
vagrant ssh #connect with VM
cd hpi-swt2
rails s -b 0 #starting rails server, the -b part is necessary since the app is running in a VM and would otherwise drop the requests coming from the host OS
  • By default, the application is served on port 3000: http://localhost:3000/
  • Edits to files in the local folder will be mirrored into the VM's hpi-swt2 folder as the folders are synced.
  • We recommend you open one terminal session that runs the development server and another one to execute commands on the machine (e.g. running tests) or use of a terminal multiplexer. Then you do not have to restart the server after each command.

3) Dive into the code

  • Run bundle install to install the dependencies of the project (they are stored in the Gemfile)
    • If the bundle command was not found, install bundler with gem install bundler
  • Run rails db:migrate RAILS_ENV=development && rails db:migrate RAILS_ENV=test to migrate the database
  • Run rspec to run the tests (RSpec is a test framework for Ruby)
  • Try to get the failing test green.

4) Commit and push

  • When you are done and the test passes, push your changes.
  • Travis CI will now try to build and test your project.

5) Check your inbox / issues

  • You will be notified of problems or new exercise work items via GitHub issues on your repository.
  • While you wait, see if your code can use some refactorings, continue reading the tutorial, or plan the next steps.

6) For each issue

  • Write a new test that documents the missing or failing behavior.
  • Commit the failing test and reference the issue.
    • The commit message could be Failing test for #<ISSUE NUMBER>.
    • There is no need to push the failing commit.
  • Fix the issue and make your test pass. Then commit the changes.
    • While an issue is open, the exercise will create comments on the issue, notifying you of errors

7) Repeat steps 4 to 6 until the exercise is complete.

Tips:

  • The beginning of this exercise is designed to be solved while reading the official Rails tutorial
  • Run rspec spec/<path_to_spec>.rb to only run one set of specs
  • Have a look at /spec/factories to get inspiration for your data model
  • Besides generators and scaffolds, associations and validations are needed
  • Occasionally start up the server (rails s) and have a look at the app in your browser
  • Look at the Mockup: https://gomockingbird.com/mockingbird/index.html?project=v890g6l#v890g6l/OQMURm (author selection uses a multiple select in this version of the exercise)
  • rails db:drop && rails db:migrate deletes the database and recreates it. This might be helpful for error recovery.
  • Make sure that all local changes are committed (git status) and pushed to the upstream repository (i.e., the one on GitHub) before the deadline