YARD for documentation in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a YARD documentation comment for the method.

Ruby

# [1]
def greet(name)
  "Hello, #{name}!"
end

Drag options to blanks, or click blank then click option'

A# TODO: add docs

B# @param name [String] the name to greet

C# greet method

D# This method prints a greeting

Attempts:

3 left

💡 Hint

Common Mistakes

Writing a plain comment without '@param' tag

Using incorrect tag like '@argument' instead of '@param'

The correct YARD tag for documenting a method parameter is '@param' followed by the parameter name and its type.

2fill in blank

medium

Complete the code to add a YARD documentation tag describing the return value.

Ruby

# @return [1]
def add(a, b)
  a + b
end

Drag options to blanks, or click blank then click option'

A[Array] the sum of a and b

B[String] the sum of a and b

C[Integer] the sum of a and b

D[Hash] the sum of a and b

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong return type like String or Array

Omitting the return type brackets []

The method returns the sum of two integers, so the return type is '[Integer]'.

3fill in blank

hard

Fix the error in the YARD documentation tag for the method parameter.

Ruby

# @param [1] [String] the user's name
def welcome(user_name)
  "Welcome, #{user_name}!"
end

Drag options to blanks, or click blank then click option'

Ausername

Bname

Cuser

Duser_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name in the '@param' tag

Misspelling the parameter name

The parameter name in the method is 'user_name', so the '@param' tag must use the exact same name.

4fill in blank

hard

Fill both blanks to document a method with a parameter and a return value using YARD.

Ruby

# @param [1] [Integer] the number to double
# @return [2] the doubled number
def double(num)
  num * 2
end

Drag options to blanks, or click blank then click option'

Anum

B[Integer]

CInteger

D[String]

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting brackets in '@return' tag

Using wrong parameter name

The parameter name is 'num' and the return type should be '[Integer]' with brackets.

5fill in blank

hard

Fill all three blanks to document a method with two parameters and a return value using YARD.

Ruby

# @param [1] [String] the first name
# @param [2] [String] the last name
# @return [3] the full name
def full_name(first, last)
  "#{first} #{last}"
end

Drag options to blanks, or click blank then click option'

Afirst

Blast

C[String]

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'String' without brackets in '@return'

Swapping parameter names in '@param' tags

The parameter names are 'first' and 'last', and the return type should be '[String]' with brackets.

Practice

1. What is the main purpose of using YARD in Ruby code?

easy

A. To automatically fix syntax errors in Ruby code

B. To speed up the execution of Ruby programs

C. To write clear documentation inside the code using special comments

D. To convert Ruby code into other programming languages

Solution

1. Step 1: Understand YARD's role

   YARD is a tool to add documentation inside Ruby code using comments.

2. Step 2: Identify the correct purpose

   It helps explain code clearly, not speed execution or fix errors.

3. Final Answer:

   To write clear documentation inside the code using special comments -> Option C

4. Quick Check:

   YARD -> documentation [OK]

Hint: YARD is for documentation, not code execution [OK]

Common Mistakes:

• Thinking YARD runs or speeds up code
• Confusing YARD with debugging tools
• Assuming YARD converts code to other languages

2. Which of the following is the correct way to document a method parameter using YARD?

easy

A. # @param name [String] the user's name

B. // @param name String the user's name

C. /* @param name String the user's name */

D.

Solution

1. Step 1: Recognize Ruby comment style

   Ruby uses # for single-line comments, so YARD tags must start with #.

2. Step 2: Identify correct YARD tag syntax

   The correct format is "# @param name [Type] description".

3. Final Answer:

   # @param name [String] the user's name -> Option A

4. Quick Check:

   # -> Ruby comments [OK]

Hint: YARD tags start with # in Ruby code comments [OK]

Common Mistakes:

• Using comment styles from other languages
• Omitting square brackets around type
• Writing tags inside HTML or block comments

3. What will be the output of the following YARD comment when generating documentation?

# Adds two numbers
# @param a [Integer] first number
# @param b [Integer] second number
# @return [Integer] sum of a and b
# @example
#   add(2, 3) #=> 5
def add(a, b)
  a + b
end

medium

A. Only the method name will appear without any details

B. Syntax error because @example is not allowed

C. The code will run and print 5

D. Documentation showing method description, parameters with types, return type, and example usage

Solution

1. Step 1: Understand YARD comment tags

   The tags @param, @return, and @example describe method details for documentation.

2. Step 2: Recognize YARD output

   YARD generates HTML docs showing description, parameters, return type, and examples.

3. Final Answer:

   Documentation showing method description, parameters with types, return type, and example usage -> Option D

4. Quick Check:

   YARD tags -> detailed docs [OK]

Hint: YARD tags create detailed docs, not runtime output [OK]

Common Mistakes:

• Confusing documentation comments with code execution
• Thinking @example causes errors
• Expecting code output instead of docs

4. Identify the error in this YARD comment block:

# @param name String the user's name
# @return String greeting message
def greet(name)
  "Hello, #{name}!"
end

medium

A. Missing square brackets around the type in @param and @return tags

B. The method name should be capitalized

C. YARD comments must be placed after the method definition

D. The string interpolation syntax is incorrect

Solution

1. Step 1: Check YARD tag syntax

   YARD requires types in square brackets, e.g., [String], not just String.

2. Step 2: Verify other parts

   Method name capitalization and comment placement are correct; string interpolation is valid Ruby.

3. Final Answer:

   Missing square brackets around the type in @param and @return tags -> Option A

4. Quick Check:

   [Type] -> YARD requirement [OK]

Hint: Always put types in square brackets in YARD tags [OK]

Common Mistakes:

• Omitting square brackets around types
• Placing comments after method instead of before
• Confusing Ruby syntax errors with documentation errors

5. You want to document a Ruby class with YARD that has a method returning a hash with keys as symbols and values as arrays of strings. Which is the best way to write the @return tag for this method?

hard

A. # @return [Hash] a hash with keys and values

B. # @return [Hash{Symbol => Array<String>}] a hash mapping symbols to arrays of strings

C. # @return [Array<Hash>] an array of hashes

D. # @return [Hash(Symbol, Array)] a hash with symbol keys and array values

Solution

1. Step 1: Understand complex type syntax in YARD

   YARD supports detailed type annotations like Hash{KeyType => ValueType}.

2. Step 2: Match the method return type

   The method returns a hash with Symbol keys and Array of String values, so use Hash{Symbol => Array<String>}.

3. Final Answer:

   # @return [Hash{Symbol => Array<String>}] a hash mapping symbols to arrays of strings -> Option B

4. Quick Check:

   Hash{Key => Value} -> correct syntax [OK]

Hint: Use Hash{KeyType => ValueType} for detailed return types [OK]

Common Mistakes:

• Using vague types like just Hash
• Incorrect syntax like Hash(Symbol, Array)
• Confusing array of hashes with hash of arrays