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Test answers for Ruby on Rails Test 2020

(84, CL) Last updated: May 26
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84 Answered Test Questions:

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



• User.destroy

• User.find


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


• 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?


• 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)?


• 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?


• bundle install

• generate model

• annotate

• Rails server

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


• Embedded Ruby


• 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


• '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?



• type casting error

• test5

• 5

• testtesttesttesttest

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


• 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?


• _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?


• <% |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


• 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}"


• 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"?


• "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?



• Rails.root



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


• 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?


• 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?


• 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 ?


• controller

• helper

• model

• view

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

module PartyAnimal
        puts "Hard! Better! Faster! Stronger!"

class Person
    include PartyAnimal





• Both! and!

• None of these

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


• Class

• Controller

• Model

• Module

• View

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


• 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



• AB C

• AB D


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


• 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?
class ApplicationControllers < ActionController::Base
  rescue_from Exception, with: error_handler


• Server errors

• Record not found (404)

• Routing errors

• All of these

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


• Models

• Controllers

• View helpers

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


• jQuery

• Ajax


• ajax-li

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


• 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?


• 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?


• assert_valid

• assert_select_email

• assert_select_encoded

• css_select

31. Is an AJAX call synchronous or asynchronous?


• Asynchronous

• Synchronous

• Either; it is configurable

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


• 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?


• 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


• A

• B

• C

• B and C

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


• 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?


• Data Migrations

• Factories

• Fixture Factories

• Fixtures

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


• :validate => skip

• :validate => off

• :validate => disable

• :validate => false

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


• layout 'new_layout'

• set_layout 'new_layout'

• @layout = 'new_layout'

39. What is the output of the following code?

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


• *

• *****

• *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?


• 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?


• 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?


• .valid? and .invalid?

• valid() and invalid()

• isvalid and isinvalid

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


• 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?


• <%= 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();" %>


• <% 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?


• 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


• Integer

• Float

• BigDecimal

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


• 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?


• 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?


• $ 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

51. Consider the following code snippet:

def index

The corresponding index.html.erb view is as following:


<title>Ruby on Rails sample application | <%=@title%></title>


Which of the following options is correct?


• The application will give an exception as @title variable is not defined in the controller.

• The HTML page will render with the title: Ruby on Rails sample application | <%=@title%>.

• The HTML page will render with the title: Ruby on Rails sample application |.

• The HTML page will render with the title: Ruby on Rails sample application.

52. Unit tests are used to test which of the following components of Ruby on Rails?


• Models

• Controllers

• Views

• Helper classes

53. If a controller is named "Users", what would its helpers module be called?


• UsersHelper

• UserControllerHelper

• UserHelp

54. Which of the following serves as a structural skeleton for all HTML pages created?


• application.html.erb

• default.html.erb

• index.html.erb

• layout.html.erb

55. Which of the following statements is incorrect?


• Rails does not support ODBC connectivity.

• Rails can rollback database changes in development mode.

• Rails can work and connect with multiple databases.

• Rails database information is stored in the database.yml file.

56. What is the Singleton design pattern?


• A class for which there is only ever one instance.

• A single feature application, intended to enhance usability by keeping things simple.

• A class which is never instanced, but acts as a container for methods which are used by it's subclasses.

57. Users who are new to MVC design often ask how to query data from Views. Is this possible? And if so, is this a good idea?


• It is not possible, because ActiveRecord queries cannot be made from Views.

• It is not possible, because Controllers do not provide enough information to the Views.

• It is possible, but it is a bad idea because Views should only be responsible for displaying objects passed to them.

58. What does REST stand for?


• Ruby Enclosed Standard Templating

• Resource Standard Transfer

• REasonable Standards Testing

• REpresentational State Transfer

• Rights Enabled Safety Tunnel

59. With the two models Hive and Bee; when creating a belongs_to association from the Bee model to Hive, what is the foreign key generated on Bee?


• hive_id

• hives_id

• ee_id

60. Which of the following is not true about log levels in Ruby on Rails?


• The available log levels are: :debug, :info, :warn, :error, and :fatal, corresponding to the log level numbers from 1 up to 5 respectively.

• To check the current log level, the Rails.logger.level method has to be called.

• By default, each log is created under Rails.root/log/ and the log file name is environment_name.log.

• The default Rails log level is error in production mode and debug in development and test mode.

61. When a new controller named "admin2" is created, the JS and the CSS files are created in:


• controllers

• helpers

• assets

• views

62. Select all incorrect statements regarding the Ruby Version Manager (RVM):


• RVM is a command-line tool which allows developers to easily install, manage, and work with multiple Ruby environments from interpreters to sets of gems.

• RVM provides a revision control tool to maintain current and historical versions of files such as source code, web pages, and documentation.

• Test suites, rake tasks, benchmarks and gem commands can be run against multiple Ruby versions at the same time with RVM.

• RVM cannot automate the installation and maintenance of gems, it has to be done manually.

63. Which of the following is not a built-in Rails caching strategy used to reduce database calls?


• Page Caching

• Fragment Caching

• Object Caching

• Query Caching

64. In a Rails application, the developmental and production configuration are stored in the:


• config/environment folder

• public folder

• spec folder

• task folder

65. What is the convention for methods which end with a question mark? e.g. #all?, #kind_of?, directory?


• They should always require arguments.

• They should always return a boolean value.

• They should always report a value of the object they're being called on.

66. Which of the following correctly handles the currency field?

A) add_column :items, :price, :decimal, :precision => 8, :scale => 2
B) add_money :items, :price, currency: { present: false }


• A

• B

• Both A and B are correct.

• Both A and B are incorrect.

67. How can a partial called "cart" be rendered from a controller called "ProductsController", assuming the partial is in a directory called "shared"?


• render :partial => 'shared/cart'

• partial 'shared/cart'

• render 'cart'

68. What does the 4xx series of HTTP errors represent?


• They are intended for cases in which the server seems to have encountered an error.

• They are intended for cases in which the client seems to have encountered an error.

• They indicate that further action needs to be taken by the user agent in order to fulfill the request.

• They indicate that no further action can be taken by the user agent.

69. Which of the following validations in Rails checks for null fields?


• validates_presence_of

• validates_length_of

• validates_confirmation_of

• validates_uniqueness_of

70. Using ERB for views, what filename should be given to a partial called 'login'?


• partial_login.e

• _login.html.e

• login.html.e

71. What is output of following statements?
1) "".nil? == "".empty? && "".blank? == "".empty?
2) !"".nil? == "".empty? && "".blank? == "".empty?
3) nil.nil? == nil.empty? && nil.blank? == nil.empty?
4) !"".blank? == "".present?
5) "".any? == !"".empty?
6) "  ".blank? == "  ".empty?


• 1) false 2) true 3) NoMethodError: undefined method `empty?' for nil:NilClass 4) true 5) NoMethodError: undefined method `any?' for "":String 6) false

• 1) false 2) NoMethodError: undefined method `empty?' for "":String 3) true 4) true 5) NoMethodError: undefined method `any?' for "":String 6) false

• 1) false 2) true 3) true 4) true 5) false 6) false

• 1) false 2) true 3) false 4) true 5) true 6) false

72. For the String class, what's the difference between "#slice" and "#slice!"?


• None, "#slice" is just an alias for "#slice!".

• There is no "#slice!" method in Ruby on Rails.

• "#slice" returns a new object, "#slice!" destructively updates ??? mutates ??? the object's value.

73. Which of the following controller actions (by default) are best suited to handle the GET HTTP request?


• index

• show

• create

• edit

• update

74. Rails automatically requires certain files in an application. Which of the following files are automatically included without an explicit 'require' being necessary?


• All files in lib.

• All files in models, views, controllers, and files named rails.rb in lib.

• All files in models, views, controllers, and any init.rb in plugins.

• Only files explicitly referenced from an initializer in config/initializers.

75. Which of the following is true about writing tests for a Ruby on Rails application?


• Rails semi-automates the process of writing tests. It starts by producing skeleton test code in the background while models and controllers are being written.

• Running tests in Rails ensures that the code adheres to the desired functionality even after major code refactoring.

• Rails tests can simulate browser requests, and thus test the application's response without having to test it through a browser.

• All of these.

76. What is the behavior of class variables with subclasses?


• Subclasses inherit a default value for the class variable, which can then be modified for just the subclass.

• Class variables are shared between between all classes in the hierarchy.

• Class variables are not inherited.

77. There is a table named Product in a Rails application. The program is required to fetch any 5 rows where the productid is 2. Which of the following is the correct option to perform this action?


• Product.find(:productid=>2), :offset=>5

• Product.find(:productid=>2), :limit=>5

• Product.find(:productid=>2), :only=>5

78. Consider the following information for a User view:

user_path named route with value "/users/"

@user = 1

Now, consider the following code in the HTML erb template:

<%= link_to user_path(@user), "Angel" %>

What will be the HTML output of this code?


• a href='/users/1'>Angel</a

• a href='Angel'>/users/1</a

• a href='/users/1'>/users/1</a

• a href='Angel'>Angel</a

79. If a model called BlogComment is defined, what would its DB table be called?


• blog_comment

• blogcomments

• blog_comments

80. What is the output of the following code?
$val = 20
print "Sample Text\n" if $val


• 20

• Sample Text

• No output

• Syntax error

81. Which of the following options will disable the rendering of the view associated with a controller action?


• render :layout=>false

• render :layout=>nil

• render :layout=>disabled

• render :layout=>off

82. The =~ operator is used to do inline Regular Expression matching, for instance:

"function" =~ /fun/
"function" =~ /dinosaurs/

What are possible return values for the =~ matcher?


• true, false

• "fun", nil

• 1 and 0 only

• 0 and nil only

• nil, 0, and any positive integer

83. Which of the following options is used to create a form HTML in the erb files?


• form_for

• create_form

• form_do

• form

84. Which of the following actions is fired by default when a new controller is created?


• index

• run

• show

• login