How to Debug Using byebug (Ruby Debugger)

—byebug` is a powerful debugging gem for Ruby applications, particularly useful in Ruby on Rails.

🛠️ Installation

Scenario	Instructions
Rails Project	Ensure gem 'byebug' is present in your Gemfile (usually in the development and test groups), then run bundle install.
Standard Ruby Project	Run the command gem install byebug and add require 'byebug' at the top of your Ruby file.

🛑 Setting a Breakpoint

Simply add the keyword byebug to the line of code where you want the program to pause:

def process_data(data)
  intermediate_result = data.map(&:upcase)
  byebug # The program will stop here
  final_result = intermediate_result.join(', ')
  return final_result
end

When the program executes this line, the debugger shell will appear in your Terminal.

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📝 Essential byebug Commands

Here are the commands you use while inside the (byebug) session:

Command	Shorthand	Function	Explanation
next	n	Execute the next line.	Does not step into methods called on the current line.
step	s	Execute the next line.	Steps into the called method (if any).
continue	c	Continue execution.	Runs the program normally until the next breakpoint or termination.
finish	fin	Run until the current method exits.	Stops on the line immediately following the method call.
print	p	Print value.	Prints the value of a variable or expression (e.g., p data).
pp		Pretty print value.	Prints the value in a more readable, formatted way.
break	b	Set a new breakpoint.	Sets a break at a line (e.g., b 25) or a method (b MyClass#method).
list	l	Display code.	Shows the source code surrounding the current line.
where	w	Display stack trace.	Shows the sequence of method calls that led to the current location.
quit	q	Exit and stop program.	Exits the debugger and terminates the program execution.