100+ Free PCPP2 Practice Questions

Testing principles and techniques

unittest (TestCase, setUp/tearDown, setUpClass/tearDownClass, setUpModule, assertEqual/assertTrue/assertRaises/assertIn/assertAlmostEqual, skip/skipIf/skipUnless/expectedFailure, test discovery with python -m unittest discover); unittest.mock (Mock, MagicMock, return_value, side_effect, assert_called_with, patch, patch.object as decorator and context manager); pytest (function/class/module/session fixtures, @pytest.mark.parametrize, conftest.py for shared fixtures, monkeypatch, pytest.raises); doctest fundamentals.

Design patterns

GoF patterns in Python: Singleton via __new__ or metaclass; Factory Method and Abstract Factory; Facade; Proxy (virtual, protection, remote, caching); GoF Decorator (object composition) versus Python @decorator syntax; Observer (publish/subscribe); Command with execute/undo; Template Method via abstract base classes; State and Strategy and how they differ in intent. SOLID principles (SRP, OCP, LSP, ISP, DIP) implemented with abstract base classes and typing.Protocol.

Interprocess communication

threading (Thread, daemon=True, start/join, Lock/RLock, Semaphore/BoundedSemaphore, Event, Condition with notify/notify_all, Barrier, thread-safe queue.Queue), the Global Interpreter Lock and CPU- vs I/O-bound implications, multiprocessing (Process, Queue, Pipe, Pool with map/imap, Manager proxies, Value and Array shared memory, spawn vs fork start methods, the if __name__ == '__main__' guard), subprocess (run with capture_output/text/check, Popen, PIPE, communicate, shell=True risks), and concurrent.futures (ThreadPoolExecutor, ProcessPoolExecutor) plus asyncio basics (async/await, asyncio.run, gather, create_task).

Network programming

socket module (AF_INET / AF_INET6, SOCK_STREAM / SOCK_DGRAM, server flow socket > bind > listen > accept > recv/send, client flow socket > connect > send/recv, sendall vs send, sendto/recvfrom for UDP, setblocking, gethostbyname and getaddrinfo), I/O multiplexing with selectors.DefaultSelector (epoll/kqueue/select under the hood), software-defined networking concepts (control plane vs data plane separation, OpenFlow controllers), and network security via the ssl module (ssl.create_default_context, TLS 1.2+, certificate chain validation, hostname checking, SNI via server_hostname).

Python-SQL and Python-NoSQL database access

DB-API 2.0 (PEP 249) concepts of Connection, Cursor, transactions, commit/rollback. sqlite3 (connect, cursor, execute/executemany, parameterized ? placeholders, fetchone/fetchmany/fetchall, sqlite3.Row, connection used as context manager auto-commits or rolls back). SQLAlchemy ORM (create_engine, sessionmaker, DeclarativeBase, session.commit / rollback / close). pymongo (MongoClient, database/collection access, insert_one, find/find_one, update_one/update_many, replace_one, create_index for query performance). redis-py basics (Redis client, set/get, decode_responses).

Clean code design, maintenance, and optimization

PEP 8 style (naming, indentation, line length, import order), PEP 257 docstring conventions, PEP 484 type hints (Optional, Union, Callable, TypeVar, Generic, list[str], dict[str,int]), PEP 544 typing.Protocol for structural subtyping, dataclasses.dataclass with frozen/slots/kw_only options, formatters and linters (black, ruff/flake8, isort, mypy/pyright), profiling (cProfile and pstats), memory optimization (__slots__ to suppress __dict__, functools.lru_cache and functools.cache, generator expressions versus list comprehensions, NumPy vectorization at a conceptual level).