Gem versions and constraints in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this version comparison?

Given the following Ruby code using Gem::Version, what will be printed?

Ruby

require 'rubygems'

v1 = Gem::Version.new('2.3.4')
v2 = Gem::Version.new('2.3.10')

puts v1 < v2

A false

B ArgumentError

C SyntaxError

D true

💡 Hint

Think about how version numbers are compared as sequences of numbers, not strings.

Gem::Version compares each part of the version number numerically. Since 4 is less than 10, '2.3.4' is less than '2.3.10'.

❓ Predict Output

intermediate

Which gem version satisfies this constraint?

Which of these gem versions satisfies the constraint '~> 3.2.1'?

A 3.2.5

B 4.0.0

C 3.3.0

D 3.2.0

💡 Hint

The '~>' operator allows patch-level updates but not minor version bumps.

The '~> 3.2.1' constraint means versions >= 3.2.1 and < 3.3.0. Only 3.2.5 fits this range.

❓ Predict Output

advanced

What error does this gem version constraint raise?

What error will this Ruby code raise when parsing the version constraint?

Ruby

require 'rubygems'

Gem::Requirement.new('>= 2.0', '< 3.0', '!= 2.5')

A SyntaxError

B No error, creates requirement successfully

C ArgumentError

D TypeError

💡 Hint

Multiple constraints can be combined in Gem::Requirement.

Gem::Requirement accepts multiple constraints as arguments and combines them logically. No error is raised here.

❓ Predict Output

advanced

What is the output of this complex version check?

What will this Ruby code print?

Ruby

require 'rubygems'

req = Gem::Requirement.new('~> 1.5', '!= 1.5.3')
puts req.satisfied_by?(Gem::Version.new('1.5.3'))

A ArgumentError

B true

C false

D SyntaxError

💡 Hint

The '!=' constraint excludes a specific version even if it matches the '~>' range.

The requirement excludes version 1.5.3 explicitly, so satisfied_by? returns false for that version.

🧠 Conceptual

expert

How many versions satisfy this complex constraint?

Given the constraint '>= 2.0', '< 3.0', '!= 2.5', how many versions in the list satisfy it? Versions: ['1.9.9', '2.0.0', '2.4.9', '2.5.0', '2.5.1', '3.0.0']

A 3

B 4

C 2

D 5

💡 Hint

Check each version against all constraints carefully.

Versions 2.0.0, 2.4.9, and 2.5.1 satisfy all constraints. 2.5.0 is excluded by '!= 2.5', 1.9.9 is less than 2.0, and 3.0.0 is not less than 3.0.