13. Exceptions & Testing#
This chapter covers two practical skills every programmer needs:
handling errors and invalid input gracefully
diagnosing and fixing bugs systematically
Why This Matters
As programs grow, failures shift from obvious syntax errors to subtle runtime behavior:
malformed input
missing files
invalid assumptions
state bugs that only appear for specific cases
You need a system for both prevention and diagnosis.
Learning Goals
By the end of this chapter, you should be able to:
validate inputs before risky operations
handle runtime exceptions intentionally
debug behavior using breakpoints and watches
communicate failures with actionable messages