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reflection to tealeaf course3 week3

admin 11月 13, 2020 0

In week 2, Tealeaf talked about how to test controller, and this week, I got a more comprehensive test consideration for controller and user interaction.

###For Controller Test

  • Everytime add a function feature, also need to add a test for it.
  • Everytime find a bug, also add a test for it.

###DRY

RSpec also offer two ways to DRY code.

- Macro

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$ mkdir spec/support
$ touch macros.rb

And we can move repeatedly code into here, for example, we usually need to set a login user:

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def set_current_user(user = nil)
  session[:user_id] = (user || Fabricate(:user)).id
end

and find user

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def current_user
  User.find(session[:user_id])
end

- Shared Examples

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$ touch spec/support/share_examples.rb

A test method may be called through different controllers:

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shared_examples 'requre_sign_in' do
  it 'redirects to the root page'
    action
    expect(response).to redirect_to root_path
  end
end

Be careful: action is a variable, then when using it:

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it_behaves_like 'require_sign_in' do
  let(:action) { get :index }
end

###Feature Specs

There are two methods to test user interactions, one is request spec and this is deprecated by Capybara. The other one is feature specs, recommended by Capybara.

Capybara offer functions that we can click link/button, fill text field…etc, to interactive with UI.

- Install Capybara gem

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group :test
  gem 'capybara'
end

Also add this line to test helper file

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requrire 'capybara/rails'

And

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$mkdir spec/features
$touch user_signs_in_spec.rb

- A sample for user operation:

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feature 'user interacts with the queue' do 

  scenario 'user adds and reorder videos in the queue' do
    category    = Fabricate(:category)
    monk        = Fabricate(:video, title: 'monk', category: category)
    futurama    = Fabricate(:video, title: 'futurama', category: category)
    south_park  = Fabricate(:video, title: 'south park', category: category)

    sign_in
    expect(page).to have_content 'You have signed in.'

    add_video_to_queue(monk)
    expect(page).to have_content(monk.title)

    visit video_path(monk)
    expect(page).not_to have_content('+ My Queue')

    add_video_to_queue(futurama)
    add_video_to_queue(south_park)

    set_video_order(monk, 3)
    set_video_order(futurama, 1)
    set_video_order(south_park, 2)

    expect_video_order(monk, 3)
    expect_video_order(futurama, 1)
    expect_video_order(south_park, 2)
  end
end

def add_video_to_queue(video)
  visit home_path
  find("a[href='/videos/#{video.id}']").click
  expect(page).to have_content(video.title)
  click_link '+ My Queue'
end

def set_video_order(video, order)
  within(:xpath, "//tr[contains(.,'#{video.title}')]") do
    fill_in 'queue_items[][position]', with: order
  end
end

def expect_video_order(video, order)
  expect(find(:xpath, "//tr[contains(.,'#{video.title}')]//input[@type='text']").value).to eq(order.to_s)
end

here I choose to use :xpath.

- One level for scenario

In above sample, I extract methods add_video_to_queue, set_video_order, and expect_video_order. This is we want to keep a principle Abstract one level for scenario. Encapsulating logic code and keep main code readable on the same abstract level can help reader to review.

###Rails Conventions

- Merge Params

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= form_tag update_queue_path do
  ...
  %td= text_field_tag 'queue_items[][position]', queue_item.position
  =hidden_field_tag 'queue_items[][id]', queue_item.id

  =submit_tag 'Update'

Then we will get a hash value params[queue_items] = {position: xxx, id: xxx}

- select_tag

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%td= select_tag 'queue_items[][rating]', options_for_video_reviews(queue_item.rating), include_blank: true

And options_for_video_reviews:

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def options_for_video_reviews(selected = nil)
  options_for_select((1..5).map { |num| [pluralize(num, 'Star'), num]}, selected)
end

Be careful that [pluralize(num, 'Star'), num] is a pair value.

- ActiveRecord Transactions

A sample from Rails Tutorial

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ActiveRecord::Base.transaction do
  david.withdrawal(100)
  mary.deposit(100)
end

If any one of david.withdrawl or mary.deposit raise an exception(Be careful: there must be a raising error to trigger transaction), all database record in this action will be rollback. It deal with batch action with database. So I have to care about what functions will raise an exception when fail. Ex. update return a fail, and update! raise an exception.

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