Week 2 Questions

Question 1

How would you generate a mailer and it’s email templates?

Answer 1

rails generate mailer UserMailer account_activation password_reset

Question 2

When you generate a mailer in the command line it creates two views for the email template. Why does this happend

Answer 2

One for plain-text email and one for HTML email.

Question 3

What does user:references add in this migration:

rails generate model Micropost content:text user:references

Answer 3

Automatically adds a user_id column (along with an index and a foreign key reference)3 for use in the user/micropost association.

Question 4

How do you set a default scope for an object to be in descending order

Answer 4

#in the model 
default_scope -> { order(created_at: :desc) }

Question 5

What validation would you write to destroy a post that belongs to a user that has been destroyed

Answer 5

#in user model
has_many :microposts, dependent: :destroy

Question 6

How would you code a shared errors partial and how would you code the render snippet?

Answer 6

<div>
    <div class="alert alert-danger">
      The form contains .
    </div>
    <ul>

  <li>

</ul>

</div>

Question 7

Explain this code:

Micropost.where(“user_id = ?”, id)

Answer 7

Find microposts where the user_id is equal to the id of the current user

Question 8

How would you use the pluralize method on microposts belonging to a user

Question 9

What does the request.referrer method do?

Answer 9

It goes to the previous URL

Question 10

In one line, how would you write an image tag that displays a micropost’s image if it has one

Question 11

In the ruby language, what are the differences between Array.length, Array.size, and Array.count?

Answer 11

Array#length method used on arrays in ruby returns the number of elements in the array

Array#size is just an alias to the Array#length method. It executes same Array#length method internally.

Array#count has some more functionalities than length/size. It can be used for getting number of elements based on some condition.
3 ways to use Array#count:
c = [1,2,3,4,4,7,7,7,9]
1. Array#count Returns number of elements in Array
c.count
=> 9
2. Array#count n Returns number of elements having value n in Array
c.count 7
=> 3
3. Array#count{|i| i.even?} Returns count based on condition invoked on each element array
c.count {|i| i>5}
=> 4

Question 12

How would you write an if else statement depending on a specific controller action?

Answer 12

if params[:action] == "foo"
  # Show stuff for action 'foo'
elsif params[:action] == "bar"
  # Show stuff for action 'bar'
elsif ...
  # etc.
end

Question 13

How do you apply a layout in the controller?

Answer 13

#create a new layout_name.hmtl.erb file under layouts in views
#in the controller
layout 'layout_name'

Question 14

How do you view all the rails generator commands in the terminal?

Answer 14

rails g

Question 15

What is required at the top of each spec?

Answer 15

require ‘rails_helper’

Question 16

Write a simple feature spec for visiting the homepage and seeing a h1 tag with jar of awesome as the text

Answer 16

require 'rails_helper'
feature "user visits homepage" do
  scenario "successful visit" do
    visit root_path
    expect(page).to have_css 'h1', text: 'Jar of Awesome'
  end
end

Question 17

How would you write an acceptance test for the creation of a note?

Answer 17

require 'rails_helper'
feature "User create note" do
  scenario "successful" do
    visit root_path
    click_on "New Note"
    fill_in "Conent", with: "Ate pad thai with sweet tangerines"
    click_on "Submit"

expect(page).to have_css '.notes', text: 'Ate pad thai with sweet tangerines'   end end

Question 18

Where do you place Object Pattern

Answer 18

spec/support/object_pattern.rb

Question 19

How do you include Capybara methods in a Object Pattern file?

Answer 19

include Capybara::DSL in the class

class NewNoteForm
include Capybara::DSL
end

Question 20

When writing methods for Object Pattern, why would you return self in this method?
  def visit_page
    visit('/')
    click_on "New Note"
    self
  end

Answer 20

You return self so that you can chain multiple methods to the object.

Question 21

What do you have to add to the top of the spec to use and Object Pattern object?

Answer 21

require_relative ‘../support/new_note_form’

Question 22

How do you code a let statement for a new_note_form

Answer 22

let(:new_note_form){NewNoteForm.new}

Question 23

How would you write a scenario test using Factory Girl that visits the show page of a particular note object that has content ‘Just did it’?

Answer 23

scenario ‘note page’ do
note = FactoryGirl.create(:note, content: ‘Just did it’)
visit(‘/notes/#{note.id}’)

expect(page).to have_content('Just did it')   end

Question 24

fix this–>How would you write the enum for a privacy option for a note class in the note.rb file? How would you write the input for a privacy option using simple form?

Answer 24

simple form in views

#note.rb
enum privacy: [:public_note, :private_note, :friends_access]

Question 25

Explain this line of code note = FactoryGirl.create(:note, content: ‘Just did it’)

Answer 25

variable name note
is equal to
A Factory Girl create factory called :note
In this situation we are over riding the default factory’s value of the content: attribute with ‘Just did it’

Question 26

How would you code a sequence in a note factory for the content attribute?

Answer 26

sequence(:content){|n| “Note content #{n}”}

Question 27

How would you create a sub factory for a note factory with private access?

Answer 27

factory :public_note do
privacy Note.privacy[:public_access]
end

Question 28

Explain this line of code:

notes = FactoryGirl.create_list(:note, 3)

Answer 28

variable notes
equal
FactoryGirl creates list of 3 note factories

Question 29

What does controller do?

Answer 29

1. authenticate and authorize requests
2. handle models
3. create response
   a) render template
   b) respond with required format and headers (e.g. JSON)
   c) redirect to another route

Question 30

RSpec.describe NotesController, type: :controller do

end
What parts of this line of code can can be removed/are optional?

Answer 30

#new code
describe NotesController do
end

# type: :controller
Because our spec is placed in the controller folder, Rails knows that this spec if for a controller and the line of code is not necessary but still works if you want your spec to be extra specific

Question 31

How do you write the describe description for testing controller actions?

Answer 31

decribe "GET new" do
#request type
#name of action

Question 32

What are the 4 things you should write testing for when testing controllers?

Answer 32

authentication
authorization
response
data assignment

Question 33

what gem must you add to your gemfile to test controllers?

Answer 33

gem ‘rails-controller-testing’

Question 34

How do you test for a get response of the new page?

Answer 34

it “renders :new template” do
get :new
expect(response).to render_template(:new)
end

Question 35

Write the rest of this test

it “assigns new Note to @note”

Answer 35

it “assigns new Note to @note” do
get :new
expect(assigns(:note)).to be_a_new(Note)
end

#assigns contains all instance variables of the action
#assigns takes a symbol as the instance variable name
#be_a_new takes a class and makes sure that the assigned object is a new measure of this provided class

Question 36

Finish the rest of this test:
let(:note) {FactoryGirl.create(:public_note)}
it “renders :show template” do
end

Answer 36

let(:note) {FactoryGirl.create(:public_note)}
it “renders :show template” do
get :show, id: note.id
expect(response).to render_template(:show)
end

Question 37

#The class is Note
#Include a factory for an inherited factory called :public_note
it "redirect_to :show template" do

  end

Answer 37

it “redirect_to :show template” do
post :create, note: FactoryGirl.attributes_for(:public_note)
expect(response).to redirect_to(note_path(assigns[:note]))
end

Question 38

What does this code do?

expect {
post :create, note: FactoryGirl.attributes_for(:public_note)
}.to change(Note, :count).by(1)

Answer 38

it compares the count of Note before and after the code in expect is run after comparing, the count should change by 1

Question 39

What does the change matcher do?

Answer 39

The change matcher is used to specify that a block of code changes some mutable state.
You can specify what will change using either of two forms:

expect { do_something }.to change(object, :attribute)
expect { do_something }.to change { object.attribute }
You can further qualify the change by chaining from and/or to or one of by, by_at_most,
by_at_least.

Question 40

In Capybara, what is the difference between:
click_link(‘Link Text’)
click_button(‘Save’)
click_on(‘Link Text’)

Answer 40

click_link(‘Link Text’)# clicks on links
click_button(‘Save’)# clicks on buttons
click_on(‘Link Text’)# clicks on either links or buttons

Question 41

What is assigns(:note) equivalent to while used as an argument in the expect() method?

Answer 41

it is equivalent to an instance variable

Question 42

When writing an action for a Page Object Pattern class, what does the params={} in the action fill_in_with  do?
def fill_in_with(params={})

Answer 42

This action takes attributes that will be passed into the params of the page

Question 43

How would you provide a defalut value for the following action of a Page Object Pattern class?
def fill_in_with(params = {})
fill_in(‘Title’, with: :title, ‘Read a book’)
fill_in(‘Description’, with: ‘Excellent read’)
select(‘Public’, from: ‘Privacy’)
check(‘Featured achievement’)
attach_file(‘Cover image’, “#{Rails.root}/spec/fixtures/cover_image.png”)

self   end

Answer 43

wrap the value in params.fetch(:attribute_symbol, value_to_make_defalut)

example:
fill_in(‘Title’, with: params.fetch(:title, ‘Read a book’params.fetch)

Question 44

What is the definition of:

fetch(key, *args)

Answer 44

Returns a parameter for the given key. If the key can’t be found, there are several options: With no other arguments, it will raise an ActionController::ParameterMissing error; if more arguments are given, then that will be returned; if a block is given, then that will be run and its result returned.

params = ActionController::Parameters.new(person: { name: ‘Francesco’ })

params. fetch(:person) # => {“name”=>”Francesco”}
params. fetch(:none) # => ActionController::ParameterMissing: param is missing or the value is empty: none
params. fetch(:none, ‘Francesco’) # => “Francesco”
params. fetch(:none) { ‘Francesco’ } # => “Francesco”

Question 45

When would you use sequences in FactoryGirl

Answer 45

If you want to create multiple objects to be tested and you want to by-pass uniqueness validations set in the model

Question 46

How do you write the describe description shorthand for a method and an instance method?

Answer 46

describe ‘.authenticate’ do

describe ‘#admin?’ do

Question 47

What is the difference between Class and Instance Methods

Answer 47

Class methods are methods that are called on a class and instance methods are methods that are called on an instance of a class.
example:
class Foo
  def self.bar
    puts 'class method'
  end

def baz
puts ‘instance method’
end
end

Foo.bar # => "class method"
Foo.baz # => NoMethodError: undefined method ‘baz’ for Foo:Class

Foo.new.baz # => instance method
Foo.new.bar # => NoMethodError: undefined method ‘bar’ for #

Question 48

Name 3 ways to create a class method in ruby

Answer 48

# Way 1
class Foo
  def self.bar
    puts 'class method'
  end
end

Foo.bar # “class method”

# Way 2
class Foo
  class << self
    def bar
      puts 'class method'
    end
  end
end

Foo.bar # “class method”

# Way 3
class Foo; end
def Foo.bar
  puts 'class method'
end

Foo.bar # “class method”

Question 49

Name 3 ways to create an instance method in ruby

Answer 49

class Foo
  def baz
    puts 'instance method'
  end
end

Foo.new.baz # “instance method”

Way 2
class Foo
attr_accessor :baz
end

foo = Foo.new
foo.baz = ‘instance method’
puts foo.baz

# Way 3
class Foo; end

foo = Foo.new
def foo.bar
puts ‘instance method’
end

Foo.new.baz # “instance method”

Question 50

How long should a spec description be?

Answer 50

40 characters
If longer consider using the context method:
BAD
it 'has 422 status code if an unexpected params will be added' do
GOOD
context 'when not valid' do
  it { is_expected.to respond_with 422 }
end

Question 51

What is lazy loading and explain a benefit of it?

Answer 51

Your database is queried only when data from the database is required for some kind of manipulation in code.
This design pattern decreases the time required by an application to boot by distributing the computation cost during the execution. Also, if a specific feature is never used, the computation won’t be executed at all.