Testing – What is it, why is it useful, how to do it

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Testing – What is it, why is it useful, how to do it

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testing-talk

talk about testing

On Github mbriggs / testing-talk

Testing

What is it, why is it useful, how to do it

Created by Matt Briggs / @googleninja

What's the Point

- Testing is really really really hard - It takes valuable time - We shouldn't spend time on hard things unless they provide value - Always keep the value proposition in mind - All that being said, testing is the primary tool to enable the quick delivery of high quality software.

Flavours Of Testing

  • Acceptance Tests
  • Unit Tests
- There are several types of testing you can do, they all accomplish different things - Acceptance - tells you when your app is broken - Unit - provides very quick feedback on if your class still makes sense

Acceptance Tests

Quality

Properties of an Acceptance Test

  • End to End
  • Potentially Larger Scope
  • Somewhat Fragile
  • Slow

How to write an Acceptance Test

Capybara RSpec DSL

    feature "Signing in" do
      background do
        User.make(:email => 'user@example.com', :password => 'caplin')
      end

      scenario "Signing in with correct credentials" do
        visit '/sessions/new'
        within("#session") do
          fill_in 'Login', :with => 'user@example.com'
          fill_in 'Password', :with => 'caplin'
        end
        click_link 'Sign in'
        expect(page).to have_content 'Success'
      end
    end

When to write an acceptance test

- Usually do not test corner cases - Not going for 100% coverage - Cover the typical paths through the app a user would take

Unit Tests

Feedback and Code Quality

Properties of a Unit Test

  • Fast
  • Focused
  • Clear
  • Isolated

Unit tests give rapid feedback

- feedback is important - manual checking doesnt scale - unit tests being fast give you that feedback pretty much as you type

Unit tests expose quality issues, like tight coupling

- The act of isolating a test should be simple. When it isn't, that is a smell - Listen to your tests, don't just man through them

Anatomy of a Unit Test

  • Arrange
  • Act
  • Assert

How to write a Unit Test

RSpec

    TBD!

How to write a Unit Test

Mocha

    TBD!

Unit Testing is HARD

- Writing tests is hard, you get better by doing it - Testing should always provide value, if it doesn't, question how to do it better - Try not to write brittle tests, they make the value proposition worse instead of better - Only write tests around code which could possibly break

TDD is a valuable tool

- TDD = Red => Green => Refactor - It is a discipline that keeps you from going down bad paths - It re-orders the way you think about problems - At the end of the day, write tests over not writing tests - I really like TDD, I don't use it all the time. It is a tool

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