Creating a gem basics in Ruby - Practice Exercises

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this gemspec version code?

Consider this snippet from a gemspec file defining the gem version. What will be printed when running this Ruby code?

Ruby

module MyGem
  VERSION = "1.2.3"
end

puts MyGem::VERSION

A Error: uninitialized constant MyGem

B MyGem::VERSION

C version 1.2.3

D 1.2.3

💡 Hint

Look at how constants are accessed inside modules in Ruby.

The constant VERSION inside the module MyGem is accessed with MyGem::VERSION, which returns the string "1.2.3". The puts prints this string.

🧠 Conceptual

intermediate

Which file is essential to define a Ruby gem's metadata?

When creating a Ruby gem, which file must you create to specify the gem's name, version, summary, and authors?

A Gemfile

B gemspec

C README.md

D Rakefile

💡 Hint

This file ends with .gemspec and is used by RubyGems.

The gemspec file contains metadata about the gem such as its name, version, authors, and summary. Gemfile is for dependencies, Rakefile for tasks, README.md for documentation.

🔧 Debug

advanced

Why does this gemspec raise an error?

Look at this gemspec snippet. Why does it raise a SyntaxError? s.name = "my_gem" s.version = 0.1.0 s.summary = "A sample gem"

Ruby

Gem::Specification.new do |s|
  s.name = "my_gem"
  s.version = 0.1.0
  s.summary = "A sample gem"
end

A Version must be a string, not a float or number

B Missing comma between version numbers

C The block variable s is not defined

D The gemspec must use single quotes for strings

💡 Hint

Look carefully at the version assignment syntax.

The version must be a string like "0.1.0". Writing 0.1.0 without quotes is invalid Ruby syntax and causes a SyntaxError.

📝 Syntax

advanced

Which option correctly defines a gem's authors array in gemspec?

Select the correct syntax to assign multiple authors in a gemspec file.

Ruby

Gem::Specification.new do |s|
  s.authors = ???
end

A ["Alice", "Bob"]

B "Alice, Bob"

C {Alice, Bob}

D ("Alice", "Bob")

💡 Hint

Authors should be an array of strings.

The authors attribute expects an array of strings. Option A uses square brackets to create an array. Option A is a single string, C and D are invalid Ruby syntax for arrays.

🚀 Application

expert

How many files are created by default when running `bundle gem my_gem`?

When you run the command `bundle gem my_gem` to create a new gem skeleton, how many files are created by default (excluding hidden files)?

A 10

B 5

C 8

D 12

💡 Hint

Count files like gemspec, README, lib files, and test files generated.

By default, `bundle gem` creates around 8 files including the gemspec, README.md, Rakefile, lib directory with main file, and test files.