Debugging with pry and byebug in Ruby - Mini Project: Build & Apply

Debugging with pry and byebug

📖 Scenario: You are working on a simple Ruby program that calculates the total price of items in a shopping cart. Sometimes, the total price is not what you expect. To find the problem, you will use debugging tools pry and byebug to pause the program and check values step-by-step.

🎯 Goal: Learn how to use pry and byebug to debug a Ruby program by inserting breakpoints and inspecting variables.

📋 What You'll Learn

Create a hash called cart with specific items and prices

Add a variable discount_threshold to set a price limit

Use pry or byebug to pause the program inside a loop

Print the final total price after applying discount logic

💡 Why This Matters

🌍 Real World

Debugging tools like <code>pry</code> and <code>byebug</code> help developers find and fix problems in their code by letting them pause and check values step-by-step.

💼 Career

Knowing how to use debugging tools is essential for software developers to efficiently troubleshoot and improve code quality.

1

DATA SETUP: Create the shopping cart hash

Create a hash called cart with these exact entries: 'apple' => 2.5, 'banana' => 1.2, 'chocolate' => 3.0, 'bread' => 2.0

Ruby

# Create the cart hash with items and prices
# Your code here

Need a hint?

Use curly braces {} to create a hash with keys and values separated by =>.

2

CONFIGURATION: Set the discount threshold

Create a variable called discount_threshold and set it to 5.0

Ruby

cart = { 'apple' => 2.5, 'banana' => 1.2, 'chocolate' => 3.0, 'bread' => 2.0 }
# Set the discount threshold value
# Your code here

Need a hint?

Just assign the number 5.0 to the variable discount_threshold.

3

CORE LOGIC: Use byebug to debug the total calculation

Add require 'byebug' at the top. Then, create a variable total set to 0. Use a for loop with variables item and price to iterate over cart. Inside the loop, add byebug to pause execution. Add price to total only if price is less than discount_threshold.

Ruby

require 'byebug'
cart = { 'apple' => 2.5, 'banana' => 1.2, 'chocolate' => 3.0, 'bread' => 2.0 }
discount_threshold = 5.0

# Initialize total and loop through cart with byebug breakpoint
# Your code here

Need a hint?

Use require 'byebug' to load the debugger. Insert byebug inside the loop to pause and inspect variables.

4

OUTPUT: Print the total price

Add a puts statement to print the string "Total price: " followed by the value of total

Ruby

require 'byebug'
cart = { 'apple' => 2.5, 'banana' => 1.2, 'chocolate' => 3.0, 'bread' => 2.0 }
discount_threshold = 5.0

total = 0
for item, price in cart
  byebug
  total += price if price < discount_threshold
end

# Print the total price
# Your code here

Need a hint?

Use puts with string interpolation to show the total price.