Simple chat application

technologies used

ruby 3.0.0
rails 6.1.1
postgres 12
react 17

questions and answers

Q) How do you know if your code works?
A) I like to automate testing such as unit tests, integration and end-to-end tests if any that verify the functionality of the features & pieces of the code. I feel safe and confident as a developer to ship working code that is backed by a test suite. Also, code reviews should be enforced which promotes code maintainability for all stakeholders. See testing for more information.

Q) How are you going to teach new users how to use the application?
A) The majority of the project time was spent setting up the environment, the intended technologies and test feedback loop. Keep the application well-documented at every level with inline comments and design docs before checking in, it helps with the flow, usability, and identifies edge cases or specific uses which may not be clearly apparent.

Q) What assumptions did you make?
A) The chat front-end and api are decoupled to run on different ports to allow for multiple clients on the same chat server. The database used is for persisting the user profiles, messages & channels.
Websockets should be used when you need real-time interactions, such as propagating the same message to multiple users (group messaging) in a chat app. Websockets are based on TCP connections (two-way communication), whereas RESTful APIs are stateless server-side and map resources to the app.
It is a good practice to introduce a continuous integration & continuous deployment system across the project. With continuous delivery, new users will be able to use the latest version of the application, get notified of upcoming updates and rollback any changes if necessary.

next steps

Q) Possible next steps if you had more time.
A) If I had more time, I will:

prioritize the core functionality of the application to meet the front-end and back-end requirements
contribute more test cases to achieve an above 90% test coverage across the application
work on setting up a live demo instance using a platform as a service such as Heroku. As a result, it will eliminate setup & installation times
containerize the application to reduce installation complexity and system depedencies. Using Docker or similar orchestration, one can setup service discovery and provide runnable images that help with platform independence
refactor SOLID/design patterns, cleanup any unnecessary code or dependencies, invest in more automation tooling such as selenium/jest for front-end testing, test factories, code coverage tooling, CI/CD
add screenshots, more notes on assumptions, tradeoffs in design & implementation

installation instructions

Make sure git is installed by running git --version, if not installed, see the following:
a) if on Mac,

brew update
brew tap homebrew/versions
brew upgrade --all
brew install git

if on Linux Ubuntu

apt update
apt install git

Other Linux package managers include pacman, yum, rpm etc

Install PostgreSQL, NPM and Ruby on Rails. It is recommended to install a Ruby version manager such as rbenv to manage application environments.
a) if on Mac or Linux Ubuntu, in Terminal

$ brew install postgresql
- OR -
$ apt install postgresql postgresql-contrib

$ brew install node
- OR -
$ apt install nodejs

$ cd ~/dotfiles
$ git init
$ git submodule add -f git@github.com:rbenv/rbenv.git .rbenv
$ cd .rbenv
$ git submodule add -f git@github.com:rbenv/ruby-build.git plugins/ruby-build
$ git submodule add -f git@github.com:jf/rbenv-gemset.git plugins/rbenv-gemset
$ cd plugins/ruby-build
$ git pull 
$
$ rbenv install --list
$ rbenv install <ruby_version> 
$ rbenv global <ruby_version>
$ gem install rails
$ gem install bundler

notes:
<ruby_version> used is 3.0.0. rbenv can set shell, local, global versions
for web installers, visit https://www.ruby-lang.org/en/, https://www.postgresql.org/download/, https://nodejs.org/en/

if on Windows, get Linux and Windows Terminal

GET Windows Subsystem for Linux https://docs.microsoft.com/en-us/windows/wsl/install-win10#update-to-wsl-2
GET Ubuntu 20.04 LTS (Focal Fossa) from the Microsoft Store
GET Windows Terminal https://docs.microsoft.com/en-us/windows/terminal/get-started

Follow the installation instructions for Linux Ubuntu from step 2 previously

Download the project and setup the environment
a) Database

In terminal, run sudo service postgresql start to start the postgres database server. Check using pg_lsclusters
PostgreSQL server should be running on port 5432
Create the user we specified in chat_app_api/config/database.yml's development section:

$ sudo -u postgres createuser -s developer
$ sudo -u postgres psql
postgres=# \password developer
Enter and confirm the password. Then exit the PostgreSQL client
postgres=# \q

b) In terminal, clone the chat_app GitHub repository using the provided HTTPS or SSH URL
c) cd to the chat_app directory containing the front-end client and back-end API projects

d) Back-end

cd to the chat_app_api subdirectory
run bundle install
after the postgres server is running, run rake db:migrate to migrate the application database
run rails s to start the API on port 3000
open localhost:3000 in the browser

e) Front-end

cd to the chat_app_client subdirectory
run npm install
run yarn start to start the client on port 3001
open localhost:3001 in the browser

f) Exit the server(s) ctrl-c or ^C

testing

running instructions

if not already, setup the environment following installation instructions
cd to the chat_app/chat_app_api subdirectory
run rspec spec/models/user_spec.rb for the user tests
User base cases, edge cases described in chat_app/chat_app_api/spec/models/user_spec.rb

Due to brevity of time, full test coverage is due to be completed. Unit tests are for demonstration purposes. While I have a working functional solution, I have yet to produce the full test coverage and documentation to meet the high bar & expectation I was aiming for.

Additional test cases to do include:

Back-End Features

Test if I can persist my chat messages
Test if I can persist messages in specific channels I join
Test if I can see the list of all the available channels
Test if I can receive gif suggestions
Test if I can look up other users and channels
Test if I can see chat statistics of users and channels

Front-End Features

Test if I can see a list of all the channels
Test if I can join a channel and see the history of it
Test if I can send messages to a channel after I have joined it
Test if I can edit my previous messages
Test if I can delete my messages
Test if I can search for my previous messages
Test if I can interact with received messages in a channel and reply to them