Level 8 / Project 03 - Pagination Stress Lab¶

Learn Your Way¶

Read	Build	Watch	Test	Review	Visualize	Try
—	This project	—	—	Flashcards	—	—

Focus¶

Offset-based and cursor-based pagination strategies
Edge case handling: empty pages, beyond-range, partial last page
Stress testing with multiple page sizes
Invariant verification (no duplicates, no missing items)

Why this project exists¶

Pagination bugs are among the most common issues in web APIs. Off-by-one errors, empty last pages, and item drift during inserts all cause real production incidents. This lab builds both offset and cursor paginators, then stress-tests them to verify correctness.

Run (copy/paste)¶

cd <repo-root>/projects/level-8/03-pagination-stress-lab
python project.py --items 47 --page-sizes 1 5 10 25 100
pytest -q

Expected terminal output¶

{
  "data_size": 47,
  "page_sizes_tested": [1, 5, 10, 25, 100],
  "verification": [{"page_size": 1, "matches_total": true}, ...],
  ...
}
7 passed

Alter it (required)¶

Extend this project in a meaningful way — add a feature that addresses a real use case.

Break it (required)¶

Introduce a subtle bug and see if your tests catch it. If they don't, write a test that would.

Fix it (required)¶

Review your code critically — is there a design pattern that would improve it?

Explain it (teach-back)¶

Could you explain the architectural trade-offs to a colleague?

Mastery check¶

You can move on when you can: - explain why math.ceil is needed for total_pages, - describe the tradeoff between offset and cursor pagination, - write a stress test that catches off-by-one errors, - explain why the last page often has fewer items than page_size.

Mastery Check¶

Can you explain the architectural trade-offs in your solution?
Could you refactor this for a completely different use case?
Can you identify at least two alternative approaches and explain why you chose yours?
Could you debug this without print statements, using only breakpoint()?

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