Chapter 3

Question 1

What does running ‘bundle update’ accomplish?

Answer 1

Updates the gemset to match those specified by the Gemfile

Question 2

What does the ‘git mv’ command accomplish?

Answer 2

Moves the contents of one file to another file. Since we are moving, not copying, the original file is destroyed.

Question 3

How can we see Heroku’s logs to help diagnose a problem?

Answer 3

$ heroku logs

Question 4

In making a dynamic page, what are actions/views and controllers for?

Answer 4

Actions/views contain only static HTML, and controllers contain sets of actions (functions) related by a common purpose.

Question 5

What is the syntax for generating a controller?

Answer 5

$ rails genreate controller controllerName optionalAction1 optionAction2

Question 6

How can we push a branch besides master to BitBucket, thereby changing the branch we are pushing?

Answer 6

Include the -u flag and origin parameter, and add one final argument with the name of the branch to push:

$ git push -u origin static-pages

Question 7

T/F: When giving a generator a controller name, it automatically converts CamelCase to snake_case

Answer 7

T

Question 8

Explain the following command:

$ rails destroy controller StaticPages home help

Answer 8

After generating this controller, we can mimic the command with the ‘destroy’ directive instead to undo changes. Note that additional command line arguments must also be added in order to be included in the rollback

Question 9

How can we undo a database migration we performed with the db:migrate command?

Answer 9

$ bundle exec rake db:rollback

OR, to go back to the beginning:

$ bundle exec rake db:migrate VERSION=0

Question 10

Explain the rule in the routes.rb file:

get ‘static_pages/home’

Answer 10

When we passed the ‘home’ parameter to the generator for the StaticPages controller, Rails added a route to access these pages when given as part of a URL

Furthermore, by using ‘get’ we arrange for the route to respond to a GET request

Question 11

What are four of the most common HTTP operations?

Answer 11

GET, POST, PATCH, DELETE

Question 12

Explain GET, POST, PATCH, and DELETE in the context of Rails

Answer 12

GET: Used to read data; sends a request from client to server to get a page

POST: Used for creating things; a request sent by client to submit a form

PATCH: Updates things on a server

DELETE: Deletes things on a server

Question 13

What is Rake?

Answer 13

Short for Ruby make; a make-like language written in Ruby

Question 14

T/F: When using scaffolding, the resulting controller uses REST architecture, whereas when only a controller is generated, not all of the REST architecture is used

Answer 14

T

Question 15

When generating a controller, what do the additional parameters do in the controller file?

Answer 15

They are added as functions within the controller’s class

Question 16

Since the initial function in the controller file for a page (i.e. parameter to a controller generator) is empty, how does Rails render the page?

Answer 16

Since the controller inherits from ApplicationController, all it needs to do is render the view (i.e. make a static page) and doesn’t need to perform any actions

Question 17

What is the correspondence between actions and views?

Answer 17

An action like home has a corresponding view called home.html.erb.

Question 18

Where are views located?

Answer 18

In apps/views/controllerName/pageName.html.erb

Question 19

T/F: Rails must contain more than just static HTML.

Answer 19

F; Rails can contain just static HTML.

Question 20

What is a test suite?

Answer 20

A collection of automated tests for test-driven development.

Question 21

What are some guidelines for developing tests?

Answer 21

• When a test is especially short or simple compared to the application code it tests, lean toward writing the test first.
• When the desired behavior isn’t yet crystal clear, lean toward writing the application code first, then write a test to codify the result.
• Because security is a top priority, err on the side of writing tests of the security model first.
• Whenever a bug is found, write a test to reproduce it and protect against regressions, then write the application code to fix it.
• Lean against writing tests for code (such as detailed HTML structure) likely to change in the future.
• Write tests before refactoring code, focusing on testing error-prone code that’s especially likely to break.

Question 22

Where does Rails store generated test scripts?

Answer 22

In the tests directory

Question 23

What action does a generated test script use to see if a test has succeeded?

Answer 23

An assert statement:

test “should get home” do
get :home
assert_response :success
end

Question 24

How can we run a test suite?

Answer 24

$ bundle exec rake test

Question 25

T/F: In test-driven development, a passing test is written first which we get to fail.

Answer 25

F; A failing test is written first, and through development we get it to pass.

Question 26

What is the next step after getting a test to pass?

Answer 26

Refactoring the code if necessary.

Question 27

In TDD (test-driven development), what is the best place to look when a test fails.

Answer 27

Look at the error message, and try to fix what it sees as incorrect.

Question 28

What does “code smell” refer to?

Answer 28

When code gets bloated and repetitive during development, and requires refactoring to keep it clean.

Question 29

In tests, what does the ‘assert_select’ method do?

Answer 29

It lets us test for the presence of a particular tag; “selector” is a synonym for a tag

Question 30

In ERB, what is the difference between starting a tag with <%= ?

Answer 30

Including the = means the return value of the code will be printed to the webpage.

Question 31

In ERB, what does starting a tag with <%= mean?

Answer 31

The = means that the return value of the code will be inserted into the template.

Question 32

What is ERB, and what does it let us do

Answer 32

Stands for embedded Ruby (template system for dynamic content); allows us to insert Ruby code into HTML.

Question 33

In the default layout file, what does the following code do:

Answer 33

It takes the contents of another erb file and replaces the yield statement with that code.

Question 34

What is the default layout template supplied by Rails?

Answer 34

app/views/layouts/application.html.erb

Question 35

In the default layout file, what does the following code do:

Answer 35

It takes the contents of another erb file and replaces the yield statement with that code.