getting the most out of rails tests

Getting the mostout of Rails tests

Balanced tests

Integration testsand Unit tests

My story

Lots of unitsno integration

Lots of unitsno integrationthen...

Lots of integrationLots of units

Lots of unitsno integrationthen...

Lots of integrationLots of unitsthen...

?

The testing pyramid

» Use integration tests to test-drive your

features.

» Use unit tests to test specific objects,

models, modules, etc.

» Have many more unit tests than integration

tests.

Why balanced tests?

Faster test runs

(http://xkcd.com/303/, slightly edited)

Easier to improveperformance later

Easier to test-driveentire features

Less brittle tests

Better code coverage

A simpledevelopment process

Start with a sketch

Write a failingintegration test

require 'test_helper'

class CreateBugsTest < CapybaraTestCase test "can create a new bug" do visit bugs_path click_link "File new bug" assert_equal current_path, new_bug_path

fill_in "Title", with: "My new bug" fill_in "Description", with: "Short description." click_button "File bug" # ...and so on... endend

Our goalGet the first part of the test to pass

Write a failingcontroller test

test "should create bug" do assert_difference("Bug.count", 1) do post(:create, bug: { title: "My new bug", description: "Short description." }) end assert_redirected_to bug_path(assigns(:bug))end

Write some failing

unit tests

test "can create a bug" do bug = Bug.new(title: "My new bug", description: "This bug was just filed by a test.") assert bug.save, "Bug couldn't be saved: #{bug.errors.full_messages}"end

test "should not create a bug without a description" do skipend

test "should not create a bug without a title" do skipend

test "should not create a bug with too long of a title" do skipend

# ... and so on ...

test "can create a bug" do bug = Bug.new(title: "My new bug", description: "This bug was just filed by a test.") assert bug.save, "Bug couldn't be saved: #{bug.errors.full_messages}"end

# should not create a bug without a description# should not create a bug without a title# should not create a bug with too long of a title

# ... and so on ...

Make your units green,Make your controllers green

Repeat!

So, once again:1.Draw a sketch

2.Translate that sketch into a failing integration test

3.Get the first part of that test to pass3a. Write a failing controller test3b. Write some failing unit tests3c. Get the tests to pass3d. Repeat!

Aim for agood balance

Justin Weisshttp://www.justinweiss.comjustin@justinweiss.com@justinweiss

http://www.justinweiss.com/book