Selected Sessions from RailsConf 2007Jerry Richardson, jerry@jerryr.com

Chief Technologist, iBlinkink

Clean Code

• incremental improvement

• always check code in better than you checked it out

• never let the sun set on bad code

• test first => "test obsessed"

• provides the necessary flexibility

Robert Martin

“I am not allowed to make a change that breaks the

system. Every tiny change I make will keep that system

working.”

Let’s Refactor

• Principle of least surprise

• tiny steps => change each variable type, then run the tests

• shrink the granularity of your development

• create a barrier between things that change and things that don't

Is it worth it?

• crafting good solutions

• clean it up as soon as it gets messy => the dinner parable: get up and walk away from the dinner table or keep your dishes clean all the time

• bad schedules, requirements, team dynamics can all be fixed but bad code rots, ferments and becomes an inexorable weight that drags the team down.

Professional Behavior

• The "Green Band"

• Professionals write their tests first

• Professionals keep their code clean

• Professionals know that the only way to go fast is to go well.

• making things a little bit nicer => the check-in rule

Doing REST RightRecognize rest principles in what you're

already doing. Apply them to your whole process.

Orthodoxy (right teaching, right beliefs, right thoughts) versus Orthopraxy

(right practice)

Orthodoxy

• Roy Fielding's Thesis defined REST (Representational State Transfer)

• All models are wrong but some are useful. - George Box

• Leaky Abstractions

• Diagrams are wrong but useful in representing complex, real-world systems. Same thing with abstractions.

REST isn’t...

• Pretty URLs

• CRUD

• respond_to

• map.resources

• a protocol - http

• an architecture

REST is...

• the architectural style of the web

• Roy Fielding's Hierarchy

• Abstract => Communication Theory

• REST

• Web Architecture

• Concrete => Implementation

REST is...

• A resource is anything that can be named

• A resource is an object with a couple of contraints - can only implement a very small number of methods, same for all resources

• you don't access a resource -- you access a representation of it. (respond_to with format.xml, format.txt, etc.)

Orthopraxy

• Identification - URL

• Interaction (Method or Verb)

• Safety - has no side effects, incurs no obligations (get is the only method that is safe by definition)

• idempotent -- applying a function once returns the same value as applying it multiple times (get, put and delete)

Post

• post is neither safe nor idempotent => reserve it for when you need it

Content, Body of Request

• REST pushes all of the complexity into content, out of identification and interaction

• messages should be use standards and be self-descriptive, like html

• look for content types that map to your application domain - instead of to_xml, use an established type for users => do vcard instead of your arbitrary user xml

Adding Tests to Legacy Rails AppsMost first-time Rails apps are built

before a developer understands their importance. Testing is painful in many frameworks and ignored when many

people switch to using rails.

Starting

• Don't do it all at once. It won't work.

• first, run rake

• mysqladmin -u root create appname_test

• Use Migrations

• Scaffolding is broken => those tests don't work.

One Step at a Time

• find a bug, write a test

• refactor a method, write a test

• treat each method as a box - don't get pulled in to testing everything

• test one thing at a time

• Test: what goes in? what comes out? (returning something in the method)

Rake or Direct Testing

• rake or direct testing

• rake testing: rake test:uncommitted

• direct: ruby test_file.rb -n test_name to run one test in a specific file

Build Tests from Logs

• Parameters then reproduce actual requests.

What To Test

• right response code

• correct template

• variable assignment

• assignment of desired object

Questions?

Me.

Image Credits• DHH

http://flickr.com/photos/x180/503574487/

• Robert Martinhttp://flickr.com/photos/x180/503608084/

• Scott Raymondhttp://flickr.com/photos/keeg/511239686/

• Evan (Rabble) Henshaw-Plathhttp://flickr.com/photos/x180/474128166/

• Mehttp://flickr.com/photos/jackdanger/502998700/