This is a code exercise to practice how to manage and improve legacy code. It's not very big, and you can make it evolve progressively:
- Make it run.
- Make it testable and create some tests.
- Refactor and fix.
- Make it evolve, so it becomes a well-structured application.
- Make it Hexagonal :-)
A legacy codebase that resist a bit testing, by Cyrille Martraire.
First try to run it.
Then your goal is to make it testable so that you can make changes (FIXME inside) and perhaps refactor it a bit.
This code draws on a C# code kata authored by my distinguished colleague Nicolas M.; Thanks Nicolas for the good ideas in the kata!
This kata is very interesting to practice several refactor techniques.
At first, you won't be able to test it, so you should rely on secure refactor techniques as provided by your IDE.
One interesting suggestion is to define and keep two environments for this exercise: one that simulates a production setting, and one for the development/testing. This way, you can introduce changes and see how they would affect the production side. You should commit small sets of changes that doesn't break the application in production environment.
This PHP version tries to mimic the behavior of the original java.
To try the code, clone or download this repo.
Then, run composer:
composer install
This will install PHPUnit. PSR4 autoload for the QuoteBot namespace and lib folder uses classmap.
Finally, execute the run.php script to see how this program works (to say something):
php run.php
Or use the IDE facilities to run.
Important note: you must not touch the lib folder, given it is considered a vendor.
Start containers. First time docker needs to download images, so it could take a while.
docker-compose up -d
You can jump into the container
docker exec -it quotebot bash
Run composer install inside de container or
docker exec -it quotebot composer install
Run the application
docker exec -it quotebot php run.php
First, start up docker containers.
docker-compose up
Go to PHP Storm > Preferences > Languages and Frameworks > PHP
Clic CLI Interpreter …
Add Remote Interpreter from Docker
Select (radio button) docker-compose and select php service.
Go to PHP Storm > Preferences > Languages and Frameworks > PHP > Debug
Make sure XDebug port is 9001
Go to PHP Storm > Preferences > Languages and Frameworks > PHP > Test Frameworks
Add PhpUnit by remote interpreter configuration. Select the remote Interpreter you've configured before.
PHPUnit Library from composer autoloader. Path to script should be: vendor/autoload.php
Select phpunit.xml as default configuration file.
If you hesitate where to start, here are some of the tricky bits that make it hard to test:
- Lack of dependency injection:
- A static main with no args
- Static service
- Hard-coded instantiation of a service that itself instantiates its dependencies, and again
Implementation issues:
- Very slow service
- Hidden dependency to a license key in env variable
- Random return value -> non-deterministic test
- Dialog popping up prompting for user input
Other tricks:
- New Date() in the middle of calculations -> non-deterministic test
- High combinatorial of calculations lead to too many required test cases
- Stateful behavior from internal cache: first call different from next calls
- Heavy dependency called within a large loop with different values
- Use a dependency or another depending on the passed parameter