Testing

In this segment:

• Test Modules (5 minutes)
• Other Types of Tests (10 minutes)
• Useful Crates (3 minutes)
• GoogleTest (5 minutes)
• Mocking (5 minutes)
• Compiler lints and Clippy (5 minutes)
• Exercise: Luhn Algorithm (30 minutes)

This segment should take about 1 hour and 5 minutes