Upwork Ruby on Rails Test

1. Which of the following will return a User object when used with a model which deals with 

a table named User?

Answers:

• User.new

• User.destroy

• User.find

• User.save

2. In the case of Rails application performance optimization, select all valid ways to do 

assets compilation:

Answers:

• Running the rake task with the assets:precompile parameter when CSS and JavaScript files are updated.

• Set a true value for the config.assets.compile parameter in the config/environments/production.rb file.

• Implementing the Rails asset pipeline feature to minify JavaScript & CSS assets.

• All of these.

3. What is the best way to get the current request URL in Rails?

Answers:

• request.url

• request.request_uri

• request.fullpath

• request.current_path

4. How can a value be stored so that it's shared across an entire request (i.e. make it 

accessible in controllers, views and models)?

Answers:

• Put it in a global variable.

• Create a Singleton and store it in a class variable.

• Store it in a thread locally.

5. Which of the following commands adds the data model info to the model file?

Answers:

• bundle install

• generate model

• annotate

• Rails server

6. Which of the following HTML template languages are supported by Ruby?

Answers:

• Embedded Ruby

• HAML

• Mustache

• Razor

7. In a has_many association, what is the difference between build and new?
// user.rb
has_many :posts
// post.rb
belongs_to :user

Answers:

• 'new' sets the foreign key while 'build' does not.

• 'build' sets the foreign key while 'new' does not.

• 'build' sets the foreign key and adds it to the collection.

• 'new' sets the foreign key and adds it to the collection.

8. What is the output of the following code?

"test"*5

Answers:

• type casting error

• test5

• 5

• testtesttesttesttest

9. When using full-page caching, what happens when an incoming request matches a page in 

the cache?

Answers:

• The web-server serves the file directly from disk, bypassing Rails.

• Rails checks to see if there is a cached page on disk and passes it onto the server.

• Rails checks its in-memory cache and passes the page onto the server.

10. What is the difference between _url and _path while being used in routes?

Answers:

• _url is absolute while _path is relative.

• _path is relative while _path is absolute.

• _path is used in controllers while _url is used in views.

• _path is used in views while _url is used in controllers.

11. Which of the following code samples will get the index of |page| inside of a loop?

Answers:

• <% @images.each.do |page,index| %> <% end %>

• <% @images.each_with_index do |page, index| %> <% end %>

• <% @images.collect.each.at_index do |page, index| %> <% end %>

• None of these

12. Which of the following choices will write routes for the API versioning scenario 

described below?

/api/users returns a 301 to /api/v2/users
/api/v1/users returns a 200 of users index at version 1
/api/v3/users returns a 301 to /api/v2/users
/api/asdf/users returns a 301 to /api/v2/users

Answers:

• namespace :api do namespace :v1 do resources :users end namespace :v2 do resources :users end match 'v:api/*path', :to => redirect("/api/v2/%{path}") match '*path', :to => redirect("/api/v2/%{path}") end

• namespace :api do resources :users end namespace :v2 do resources :users end match 'v:api/*path', :to => redirect("/api/v1/%{path}") match '*path', :to => redirect("/api/v1/%{path}") end

• namespace :api do scope :module => :v3, &current_api_routes namespace :v3, &current_api_routes namespace :v2, &current_api_routes namespace :v1, &current_api_routes match ":api/*path", :to => redirect("/api/v3/%{path}") end

• None of these

13. What is the output of the following Ruby code?

puts "The multiplication output of 10,10,2 is #{10*10*2}"

Answers:

• 200.

• The multiplication output of 10,10,2 is #{10*10*2}.

• The multiplication output of 10,10,2 is 200.

• The code will give a syntax error.

14. What is difference between "has_one" and "belong_to"?

Answers:

• "has_one" should be used in a model whose table have foreign keys while "belong_to" is used with an associated table.

• "belong_to" should be used in a model whose table have foreign keys while "has_one" is used with an associated table.

• The two are interchangeable.

• None of these.

15. Which of the following is the correct way to know the Rails root directory path?

Answers:

• RAILS_ROOT

• Rails.root

• Rails.root.show

• Rails.show.root

16. What is best way to create primary key as a string field instead of integer in rails.

Answers:

• when creating a new table don't add primary key using this create_table users, :id => false do |t| t.string :id, :null => false ...... end execute("ALTER TABLE users ADD PRIMARY KEY (id)") if not using id as primary key then in users model add the following line class User < ActiveRecord::Base self.primary_key = "column_name" .... end

• you can add a key to column name to make it primary create_table users :id => false do |t| t.string :column_name, :primary => true end

17. In a Rails application, a Gemfile needs to be modified to make use of sqlite3-ruby gems. 

Which of the following options will use these gems, as per the new Gemfile?

Answers:

• install bundle Gemfile

• bundle install

• mate Gemfile

• gem bundle install

18. What is the recommended Rails way to iterate over records for display in a view?

Answers:

• Implicitly loop over a set of records, and send the partial being rendered a :collection.

• Use each to explicitly loop over a set of records.

• Use for to fetch individual records explicitly in a loop.

19. where we use attr_accessor and attr_accessible in rails ?

Answers:

• controller

• helper

• model

• view

20. Given the following code, where is the "party!" method available?

module PartyAnimal
    def self.party!
        puts "Hard! Better! Faster! Stronger!"
    end
end

class Person
    include PartyAnimal
end

Answers:

• PartyAnimal.party!

• Person.party!

• Person.new.party!

• Both PartyAnimal.party! and Person.party!

• None of these

21. Which part of the MVC stack does ERB or HAML typically participate in?

Answers:

• Class

• Controller

• Model

• Module

• View

22. Which of the following items are stored in the models subdirectory?

Answers:

• helper classes

• database classes

• HTML layout templates

• Config files

23. What is the output of the following code in Ruby?
x= "A" + "B"
puts x
y= "C" << "D"
puts y

Answers:

• AB CD

• AB C

• AB D

• AB DC

24. Which gem is used to install a debugger in Rails 3?

Answers:

• gem 'ruby-debug1'

• gem "ruby-debug19"

• gem "debugger19"

• gem "ruby-debugger"

25. What exception cannot be handled with the rescue_from method in the application 

controller?
e.g 
class ApplicationControllers < ActionController::Base
  rescue_from Exception, with: error_handler
  ..........
end

Answers:

• Server errors

• Record not found (404)

• Routing errors

• All of these

26. What component of Rails are tested with unit tests?

Answers:

• Models

• Controllers

• View helpers

27. Which of the following replaced the Prototype JavaScript library in Ruby on Rails as 

the default JavaScript library?

Answers:

• jQuery

• Ajax

• Script.aculo.us

• ajax-li

28. If a method #decoupage(n) is described as O(n^2), what does that mean?

Answers:

• The fewest number of operations it will perform is n*n.

• The worst case run time is proportional to the size of the square of the method's input.

• The method operates by squaring the input.

• The return value for the method will be the length of the input squared.

29. What is green-threading?

Answers:

• A design pattern where a fixed-size pool of threads is shared around a program.

• When threads are emulated by a virtual machine or interpreter.

• Where programs are run across multiple CPUs.

30. Which of the following assertions are used in testing views?

Answers:

• assert_valid

• assert_select_email

• assert_select_encoded

• css_select

31. Is an AJAX call synchronous or asynchronous?

Answers:

• Asynchronous

• Synchronous

• Either; it is configurable

32. Which of the following commands will clear out sample users from the development 

database?

Answers:

• rake db:migrate

• rake db:reset

• rake db:rollback

33. Given below are two statements regarding the Ruby programming language:

Statement X: "redo" restarts an iteration of the most internal loop, without checking loop 

condition.
Statement Y: "retry" restarts the invocation of an iterator call. Also, arguments to the 

iterator are re-evaluated.

Which of the following options is correct?

Answers:

• Statement X is correct, but statement Y is incorrect.

• Statement X is incorrect, but statement Y is correct.

• Both statements are correct.

• Both statements are incorrect.

34. Choose the best way to implement sessions in Rails 3:

A) Using CookieStore
B) By creating a session table and setting config/initializers/session_store.rb with Rails.

application.config.session_store :active_record_store
C) By setting config/initializers/session_store.rb with Rails.application.config.

session_store :active_record_store only

Answers:

• A

• B

• C

• B and C

35. Which of the following is the correct way to skip ActiveRecords in Rails 3?

Answers:

• ActiveRecords cannot be skipped.

• Use option -O while generating application template.

• Use option -SKIP_AR while generating the application template.

• Add new line SKIP: ACTIVERECORD in config.generators.

36. Which of the following is the default way that Rails seeds data for tests?

Answers:

• Data Migrations

• Factories

• Fixture Factories

• Fixtures

37. Which of the following options, when passed as arguments, skips a particular validation?

Answers:

• :validate => skip

• :validate => off

• :validate => disable

• :validate => false

38. What declaration would you use to set the layout for a controller?

Answers:

• layout 'new_layout'

• set_layout 'new_layout'

• @layout = 'new_layout'

39. What is the output of the following code?

puts "aeiou".sub(/[aeiou]/, '*')

Answers:

• *

• *****

• *eiou

• nil

40. Suppose a model is created as follows:
    rails generate model Sales
    rake db:migrate

What would be the best way to completely undo these changes, assuming nothing else has 

changed in the meantime?

Answers:

• rails reset models; rake db:rollback

• rails destroy model Sales; rake db:rollback

• rake db:rollback; rails rollback model Sales

• rake db:rollback; rails destroy model Sales

41. What is the difference between :dependent => :destroy and :dependent => :delete_all in 

Rails?

Answers:

• There is no difference between the two; :dependent => :destroy and :dependent => :delete_all are semantically equivalent.

• In :destroy, associated objects are destroyed alongside the object by calling their :destroy method, while in :delete_all, they are destroyed immediately, without calling their :destroy method.

• In :delete_all, associated objects are destroyed alongside the object by calling their :destroy method, while in :destroy, they are destroyed immediately, without calling their individual :destroy methods.

• None of these.

42. Which of the following methods is used to check whether an object is valid or invalid?

Answers:

• .valid? and .invalid?

• valid() and invalid()

• isvalid and isinvalid

43. Which of the following is the correct way to rollback a migration?

Answers:

• A migration cannot be rollbacked.

• rake db:rollback STEP=N (N is the migration number to be rollbacked)

• rake db:migrate:reset: (N) (N is the migration number to be rollbacked)

• rake db:rollback migration=N (N is the migration number to be rollbacked)

44. Which of the following is the correct syntax for an input field of radio buttons in 

form_for?

Answers:

• <%= f.radio_button :contactmethod, 'sms' %>

• <%= f.radio_button_tag :contactmethod, 'sms' %>

• <%= radio_button_tag :contactmethod, 'sms' %>

• <%= f.radio_button "contactmethod", 'sms' %>

45. Which is the best way to add a page-specific JavaScript code in a Rails 3 app?
  <%= f.radio_button :rating, 'positive', :onclick => "$('some_div').show();" %>

Answers:

• <% content_for :head do %> <script type="text/javascript"> <%= render :partial => "my_view_javascript" </script> <% end %> Then in layout file <head> ... <%= yield :head %> </head>

• In the application_helper.rb file: def include_javascript (file) s = " <script type=\"text/javascript\">" + render(:file => file) + "</script>" content_for(:head, raw(s)) end Then in your particular view (app/views/books/index.html.erb in this example) <% include_javascript 'books/index.js' %>

• In the controller: def get_script render :file => 'app/assessts/javascripts/' + params[:name] + '.js' end def get_page @script = '/' + params[:script_name] + '.js?body=1' render page end In View <script type="text/javascript",:src => @script>

• None of these

46. In order to enable locking on a table, which of the following columns is added?

Answers:

• lock_version column

• identity column

• primary key column

• lock_optimistic column

47. If a float is added to an integer, what is the class of the resulting number? i.e. 1.0 

+ 2

Answers:

• Integer

• Float

• BigDecimal

48. In a Rails Migration, which of the following will make a column unique, and then have 

it indexed?

Answers:

• add_index :table_name, :column_name, :unique => true

• add_index :unique => true ,:table_name, :column_name

• add_index :table_name, [:column_name_a, :unique => true ,:column_name_b], :unique => true

• None of these

49. Which of the following will disable browser page caching in Rails?

Answers:

• expire_page(:controller => 'products', :action => 'index')

• expire_fragment(:controller => 'products', :action => 'index')

• expire_page_fragment('all_available_products')

• expire_fragment('all_available_products')

50. Which of the following commands will test a particular test case, given that the 

tests are contained in the file test/unit/demo_test.rb, and the particular test case

is test_one?

Answers:

• $ ruby -Itest test/unit/demo_test.rb -n test_one

• $ ruby -Itest test/unit/demo_test.rb -a test_one

• $ ruby -Itest test/unit/demo_test.rb test_one

• $ ruby -Itest test/unit/demo_test.rb -t test_one