April 22, 2017

Recreating RSpec

Idea from WAT guy

describe MeetupUser do
...
end

Could also have a string - if you want a bunch of tests for a concept.

describe "hi there" do
...
end

Lazy vs. Eager

Pupr

let(name){value} #lazy
let!(:name2){value2} #eager

lazy: makes it when you want it
eager: runs it first

The order in which Ruby parases it.

Only when it sees

expect(name2).to eq("Harry")

eq("Harry") is the predicate

Generally

Want to use let(:name)
Runs once
Caches name2

Two reasons:

Want to do some setup before defining
Performance issues

let!

Need some thing to exist in the database for some side-effect.

Example: There are disaster zones in Airbnb. Would want to call with let! because then need to see effects in the database.

Before

Good for setup, i.e.Redis.set key
Good for something that you only need a side effect for
BUT if you need a reference to something you've created before -Then you would want to use let! so you can keep a reference to it

Subject

Another way to have let

subject(:hero) { Hero.first }

Allow

Example: never in Rails.env.production?

allow(Rails.env).to receive(:production?).and_return(true)

Stubbing

Stubbing: " programs that simulate the behaviors of software components (or modules) that a module undergoing tests depends on"

Example: VCR, gem that makes external API calls, saves response. Now deterministic. Hits Github API - saves response.

Service Oriented Architecture

Everything you're talking to is an API
For every single service, you're talking to - have to stub out the response.

Chron Job

Runs a test at a scheduled time.

Heroku equivalent: Heroku Scheduler In production: When you're working on a codebase, set up chron jobs to monitor performance.

Might also want to stub external classes

Unit tests: test one particular component, testing a SINGLE component
Integration tests: test components as integrated, "end-to-end testing" "Stub out all of the dependencies"
Not testing external dependencies, testing sending out correct methods
Controller specs

Everything that happens in your app, should go through your controller

Cannot have expect without stubbing*

Overwrite method

RSpecs is doing this for us under the hood

Core Features

Nested describe, before, let blocks
Expect

Thanks to Hafseb

kattak/rspecs.md