This document summarizes the process of dealing with a legacy Rails application that was over 3 years in development and had many technical issues. The goals were to reduce bugs and WTFs to zero, upgrade the app to more current Rails and Ruby versions, improve code quality by refactoring with tests, and eventually migrate the frontend to a single page application to provide a better user experience and app architecture. This process involved understanding the app, adding tests, refactoring code, upgrading dependencies, removing unnecessary code and plugins, and realizing that migrating to a SPA was a better long term solution than trying to fix all issues with the legacy Rails codebase.

1. Legacy Apps
@mlomnicki
The essence of dealing with legacy apps
is to reduce the number of WTFs down to zero.

2. Legacy Apps
Growing market.

3. There was an app...
Almost 3 years under development
2 teams. 1st from UK, 2nd from India

4. tests
there were some tests! (unit, controllers)
over 100 out of 220 fail

5. git log
fixes - 163 times
fix - 144 times
search - 52 times
changes - 40 times
final issues - 30 times

6. versions
Rails 2.3.5
ruby 1.8
no bundler

7. WTFs
(@club.secretary == current_member ||
@club.secretary == current_member)

8. WTFs
<%= @payment.new_record? ? '' : '' %>

9. WTFs
if some_condition
else
do_something

10. WTFs
Member.first(:conditions => ["member_id LIKE #{params[:id]}"])

11. WTFs
if @member.something == sth || @member.somethi
...
elsif other_long_conditions
...
else very_long_condition && looks_important
...

12. Logic
models
controllers
views
layouts
initializers (!)

13. Everything is awful
ruby code
JS
CSS
plugins used

14. Arkency took control

15. 1. Understand the app
It is hard
From the beginning you have to dive into every detail
Bugs made by your predecessor become your bugs

16. 2. Tests
BBQ
heavy
no factories or fixtures

17. 3. Code
PORO + real unit tests
Good Rails code
Nothing fancy yet (no DCI, no usecases...)

18. 4. Upgrade
It is all about plugins
Moved them to lib and simplify
Do you need them all?

19. Where is the fun?!

20. Removing code is fun
1799 files changed, 37303 insertions(+), 78770 deletions(-)

21. SPA migration is mega fun
Realize the rails-way is legacy!
It does not matter how old Rails you have

22. To fix or to rewrite?
None is correct!
SPA is the answer
Otherwise your app is still legacy...

23. Profits
Users - SPA enhances their experience
Devs - SPA is better architecture

24. Time
80% in frontend app
20% in Rails

25. Gameboxed Engine
It is the best thing since Rails
Put pressure on Andrzej to open-source it

26. Mobile app soon
Mobile is so easy now
Thank you SPA

27. Q&A