Testing gone-right

Testing Gone Right from RubyConf 2011 and others @jwo - Jesse Wolgamott

What We’ll Talk Abouts

What We’ll Talk Abouts• Mock is not a 4 letter word• Fast tests. Really Fast.• Rails Models

Mock is not a 4 letter word

Mocks• Mocks are not stubs

Mocks• Mocks are not stubs• Mocks assert Messages

Mocks• Mocks are not stubs• Mocks assert Messages• Assert on state => Stubbing

Mocks• Mocks are not stubs• Mocks assert Messages• Assert on state => Stubbing• Assert on messages => Mocking

Ruby + OOP + Mock

Ruby + OOP + Mock• is goood

Ruby + OOP + Mock• is goood• Objects should tell objects to do things

Ruby + OOP + Mock• is goood• Objects should tell objects to do things• (Tell don’t ask)

Ruby + OOP + Mock• is goood• Objects should tell objects to do things• (Tell don’t ask)• You tell to do things using messages

Mock Roles• Instead of mocking objects, try to mock roles• Wanting to mock concrete objects is a design smell

Example

Example• Restaurant system reserves tables• Instead of your interface talking to a ReservationService:• Talk to ReservationInterfaceHandler

Message Example class ReservationInterface def initialize(handler) @handler = handler end def select_table(table) @table = table end def submit_request @handler.reserve(@table) end end

And to Spec itdescribe ReservationInterface do let(:table){something_interesting_here} it "should tell the handler to reserve a table" do handler = double(reservation_handler) handler.should_receive(:reserve).with(table) machine = ReservationInterface.new(handler) machine.select_table(table) machine.submit_request end

Watch Out!

On APIs• Only Mock Types you own• Don’t mock boundary objects• If you do, you’ll duplicate code -> CODE SMELL

Other Mock Smells

Other Mock Smells• Having to setup more than 3 lines -- that’s a code smell

Other Mock Smells• Having to setup more than 3 lines -- that’s a code smell• Mocking concrete objects -- that’s a code smell

Other Mock Smells• Having to setup more than 3 lines -- that’s a code smell• Mocking concrete objects -- that’s a code smell• When tests go brittle and developers declare mocks suck -- that’s a code smell

However

However• If you have a “standard” Rails app, programmed procedurally:

However• If you have a “standard” Rails app, programmed procedurally:• Mocks are not for you

However• If you have a “standard” Rails app, programmed procedurally:• Mocks are not for you• If you encapulate your code. If you hide information (OOP). If you use messages:

However• If you have a “standard” Rails app, programmed procedurally:• Mocks are not for you• If you encapulate your code. If you hide information (OOP). If you use messages:• Mocks are for you!

Mocks Don’t Suck

Mocks Don’t Suck• If your code is hard to test, you need better code

Mocks Don’t Suck• If your code is hard to test, you need better code• If you have a test that is HARD to setup, your class (or test) is doing too much

Mocks Don’t Suck• If your code is hard to test, you need better code• If you have a test that is HARD to setup, your class (or test) is doing too much• If you see tests with uber-mocks, the answer is not to delete mocks. It’s to isolate your tests

Fast Rails Tests

Out of the Box

Out of the Box• Most Rails apps start as CRUD apps

Out of the Box• Most Rails apps start as CRUD apps• Tests start fast-ish

Out of the Box• Most Rails apps start as CRUD apps• Tests start fast-ish• Like a frog, we don’t notice the increase

“fast” tests• Tests should run in under a second• The entire rspec test suite

How?• Don’t load rails

Example Spec Run Real Time TimeWith Rails .07 s 8.1 sWithout 0.0007 s .8 s Rails

Avoid Factories

Avoid Factories• Instead, extract your code to classes with one single responsibility

Avoid Factories• Instead, extract your code to classes with one single responsibility• Rather than knowing everything about your object

Avoid Factories• Instead, extract your code to classes with one single responsibility• Rather than knowing everything about your object• Or, load methods via modules

Rails Models

Rails Models• Are Fat.

Rails Models• Are Fat.• Wait, isn’t that good?

Rails Models• Are Fat.• Wait, isn’t that good?• It’s better than controller logic

Rails Models• Are Fat.• Wait, isn’t that good?• It’s better than controller logic• But no.

What then?

What then?• Your models can have validations

What then?• Your models can have validations• Call out to policy or decision classes for business logic

What then?• Your models can have validations• Call out to policy or decision classes for business logic• Use Ruby Classes

What then?• Your models can have validations• Call out to policy or decision classes for business logic• Use Ruby Classes• Use Presenters

Example• Example of building a burrito that is delicious, and can know it’s delicious• In Isolation: https://gist.github.com/1281093• Using Modules: https://gist.github.com/ 1281064

CreditsWhy you don’t get mock objects @gregmoeckYour tests are lying to you @chrismdpFast Rails talk at gogoruco 2011 @coreyhainesTesting in Isolation. @garybernhardtdestroyalldoftware.com

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Testing gone-right

by Jesse Wolgamott on Oct 12, 2011

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Testing gone-right — Presentation Transcript