PCPP1 Practice Exam 3 — 20 Questions

Question 1

A developer is writing a Python module and wants to follow PEP 8's recommendations for imports. The module currently has the following imports: `import os`, `import sys`, `import requests`, `from collections import defaultdict`. According to PEP 8, how should these imports be grouped and ordered?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Standard library imports first, then third-party imports, each group separated by a blank line.. PEP 8 specifies that imports should be grouped in the order: standard library, third-party, and local application/library specific. Each group should be separated by a blank line. In the given scenario, `os`, `sys`, and `collections` are standard library, while `requests` is third-party. Therefore, standard library imports should come first, followed by a blank line, then third-party imports.

Answer

All imports should be sorted alphabetically regardless of origin.

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Imports should be placed on separate lines, and no blank lines are needed between groups.

Answer

Third-party imports first, then standard library imports, to highlight external dependencies.

Question 2

Which TWO of the following are required to successfully write a row to a CSV file?

Accepted Answer

An instance of csv.writer.. To write a row to a CSV file with Python's csv module, you must first create an instance of csv.writer (option B), because csv.writer wraps a file-like object and provides the writerow()/writerows() methods that perform the CSV formatting and writing. You also need a file object opened in write mode (option E), such as one returned by open('file.csv', 'w', newline=''), since csv.writer writes to that underlying file object and cannot write to a path or a read-only handle. Option A is not required because the row data can be any iterable (e.g., tuple, generator), not strictly a list of strings, and the values need not all be strings since the writer converts them. Option C is incorrect because there is no csv.close() function; you close the underlying file object (or use a with block), not the csv module. Option D is incorrect because a predefined dialect is optional — csv.writer defaults to the 'excel' dialect if none is supplied.

Answer

A list of strings to write.

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A call to csv.close().

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A predefined dialect.

Question 3

Which THREE of the following are attributes of the 'requests.Response' object?

Accepted Answer

text. Option B (text) is correct because requests.Response.text returns the response body decoded into a Unicode string using the encoding inferred from the HTTP headers or apparent encoding. Option C (status_code) is correct because requests.Response.status_code holds the integer HTTP status code (e.g., 200, 404) returned by the server. Option E (json()) is correct because requests.Response.json() is a method that deserializes the response body from JSON into Python objects (dict/list), raising a JSONDecodeError if parsing fails. Option A (socket) is not a documented attribute of Response; the underlying socket is managed by urllib3 and accessed via raw/connection internals, not as a direct Response attribute. Option D (connect()) is not a Response method; connect() belongs to HTTPAdapter/urllib3 connection handling, not to the Response object.

Answer

socket

Answer

connect()

Question 4

You are developing a Python script that needs to determine the absolute path of a file located in a directory relative to the script's location. You decide to use the os.path module. Which of the following functions should you use to obtain the absolute path without resolving symbolic links?

Accepted Answer

os.path.abspath(). os.path.abspath() computes an absolute path by combining the current working directory with the given path, normalizing it without resolving symbolic links. This matches the requirement. os.path.realpath() would resolve symlinks, os.path.normpath() only normalizes, and os.path.join() only concatenates components. Thus, abspath is the correct choice.

Answer

os.path.normpath()

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os.path.realpath()

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os.path.join()

Question 5

When using the 'requests' library to perform a GET request, which parameter should be passed to the 'params' argument to include query string parameters in the URL?

Accepted Answer

A dictionary. The requests library's params argument accepts a dictionary (or list of tuples) that it URL-encodes and appends as a query string. Passing a dict like {'q': 'python', 'page': 2} produces ?q=python&page=2 automatically. This is the idiomatic and documented usage for GET query parameters.

Answer

A tuple of values

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A single formatted string

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A list of strings

Question 6

When parsing XML with ElementTree, how do you retrieve the text content of an element?

Accepted Answer

element.text. The .text attribute of the Element object holds the text content.

Answer

element.content

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element.value

Answer

element.get_text()

Question 7

You are using configparser.ConfigParser to read a configuration file. You have a file where option names are case-sensitive. How do you ensure the parser respects this casing?

Accepted Answer

parser.optionxform = lambda x: x. By default, ConfigParser converts keys to lowercase. You must override the optionxform method of the parser instance.

Answer

parser = ConfigParser(case_sensitive=True)

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parser.set_case(True)

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parser.read(file, case='preserve')

Question 8

If you define a class with a metaclass that has a custom __call__ method, when is that __call__ method executed?

Accepted Answer

When an instance of the class is created.. The metaclass's __call__ method is invoked whenever the class created by that metaclass is instantiated (i.e., when you call the class name like MyClass()).

Answer

Every time an instance method is called.

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When the metaclass is first imported.

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When the class itself is defined.

Question 9

You are building a configuration manager that reads an INI file. A section contains the key-value pair `timeout = 30`. You need to retrieve the value as an integer, but if the key is missing, you want to get 60 without raising an exception. Which code snippet achieves this using the `configparser` module?

Accepted Answer

config.getint('section', 'timeout', fallback=60). The `getint` method of the `ConfigParser` class retrieves a value and converts it to an integer. It accepts a `fallback` argument that is returned if the key is not found, preventing a `NoOptionError`. This is the standard way to handle optional integer settings in INI files.

Answer

int(config.get('section', 'timeout', fallback=60))

Answer

config['section'].getint('timeout', 60)

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config.getint('section', 'timeout', default=60)

Question 10

You need a color chooser dialog in your application. Which module contains this functionality?

Accepted Answer

tkinter.colorchooser. The 'tkinter.colorchooser' module provides the askcolor() function.

Answer

tkinter.dialogs

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tkinter.colors

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tkinter.widgets

Question 11

In the Factory pattern, what should you do if the requested type is unknown?

Accepted Answer

Raise a ValueError.. Raising a ValueError or a custom 'UnknownTypeException' is the standard way to handle invalid inputs in a factory.

Answer

Log the error and return the base class.

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Return a default instance.

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Return None.

Question 12

You are designing a Python application that consumes a REST API which returns JSON data. The API responses can be large, and you need to process the JSON incrementally to avoid loading the entire response into memory. The server supports chunked transfer encoding. Which of the following techniques should you use with the 'requests' library to stream the response and parse it incrementally?

Accepted Answer

Set stream=True in the request and use response.iter_content() to read chunks, then parse each chunk with a streaming JSON parser like ijson.. To process large JSON responses incrementally with 'requests', you must enable streaming with 'stream=True' and then read the response in chunks using 'response.iter_content()'. Since JSON is not inherently line-delimited, you need a streaming parser like 'ijson' to parse the chunks as they arrive. This avoids loading the entire response into memory, making it suitable for large datasets.

Answer

Use response.json() directly; it automatically streams and parses the JSON without loading everything into memory.

Answer

Use requests.get() with a large timeout and rely on the operating system's memory management to handle the response.

Answer

Set stream=True and then call response.json() to parse the streamed data.

Question 13

You are implementing a REST API client in Python using the 'requests' library. The API requires authentication using OAuth 2.0. You need to obtain an access token and then use it to authenticate subsequent requests. Which TWO of the following statements about handling OAuth 2.0 with 'requests' are correct? (Choose two.)

Accepted Answer

You can use the 'requests-oauthlib' library to handle the OAuth 2.0 flow, including token refresh.. Handling OAuth 2.0 with 'requests' typically involves either using a specialized library like 'requests-oauthlib' for full flow management, or manually adding the Bearer token to the Authorization header if you already have a valid token. The core 'requests' library does not provide built-in OAuth 2.0 support, and sending tokens as query parameters is insecure and not recommended.

Answer

OAuth 2.0 access tokens are typically sent as query parameters in the URL.

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The 'requests' library automatically refreshes expired OAuth 2.0 tokens when using the 'auth' parameter.

Answer

The 'requests' library includes built-in support for OAuth 2.0 token management.

Question 14

Which TWO of the following are secure coding practices in Python?

Accepted Answer

Avoid using 'pickle' for untrusted data.. Option C is correct because Python's 'pickle' module is inherently unsafe for untrusted data: unpickling executes arbitrary code via the __reduce__ method, so deserializing attacker-controlled bytes can lead to remote code execution; safe alternatives include 'json' or other non-executable formats. Option D is correct because validating and sanitizing all user input (e.g., using allowlists, type checks, and parameterized queries) prevents injection flaws such as SQL injection, command injection, and XSS, forming a core secure coding practice. Option A is wrong because 'subprocess' with 'shell=True' passes the command through the shell, enabling shell metacharacter injection; the safe practice is 'shell=False' with an argument list. Option B is wrong because 'eval()' executes arbitrary Python expressions and is a classic code-injection vector; dynamic execution should use safer mechanisms like 'ast.literal_eval' for literals. Option E is wrong because hardcoded credentials in source code expose secrets and violate secure secret-management practices such as using environment variables or a secrets manager.

Answer

Use 'subprocess' with 'shell=True'.

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Always use 'eval()' for dynamic execution.

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Use hardcoded credentials for database connections.

Question 15

Which TWO of these identify a potential 'code smell' in Python exception handling?

Accepted Answer

Swallowing exceptions with an empty 'except' block.. Option B is a code smell because an empty 'except:' block silently swallows every exception, hiding failures and making debugging nearly impossible; at minimum the handler should log or re-raise. Option D is a code smell because 'BaseException' includes 'SystemExit', 'KeyboardInterrupt', and 'GeneratorExit', so catching it can prevent normal interpreter shutdown and interrupt handling; application code should normally catch 'Exception' or more specific subclasses. Option A is not a smell: 'finally' is the correct construct for guaranteed cleanup such as closing files or releasing locks. Option C is not a smell: catching specific exception types is the recommended practice for precise, safe error handling. Option E is not a smell: defining and raising custom exceptions improves clarity and lets callers handle domain-specific errors.

Answer

Using 'finally' for cleanup.

Answer

Catching specific exceptions.

Answer

Raising custom exceptions.

Question 16

Which function is used to check if an object is an instance of a class?

Accepted Answer

isinstance(). isinstance(obj, Class) is the standard way to check inheritance.

Answer

hasattr()

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issubclass()

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type()

Question 17

When working with raw sockets, what does the 'socket.SOCK_STREAM' constant represent?

Accepted Answer

TCP connection-oriented sockets. socket.SOCK_STREAM designates a reliable, connection-oriented byte stream, which in practice maps to TCP (or a Unix-domain stream socket). The Python socket module passes this constant to socket() to select the transport semantics, so SOCK_STREAM sockets guarantee ordered, error-checked delivery via the TCP three-way handshake. This is why HTTP, SMTP, and SSH clients built on Python sockets use SOCK_STREAM.

Answer

UDP datagram sockets

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Raw network sockets

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Unix domain sockets only

Question 18

You are building a custom HTTP client and need to handle persistent connections (keep-alive). What is the primary role of the 'Connection' header?

Accepted Answer

To request the reuse of the TCP connection. The 'Connection: keep-alive' header tells the server that the client wants to reuse the same TCP connection for multiple requests.

Answer

To signal that the server is alive

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To encrypt the connection

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To set the timeout for the connection

Question 19

How do you properly handle a non-200 status code when using 'requests' if you want to avoid manual status code checking?

Accepted Answer

Use response.raise_for_status(). Calling response.raise_for_status() will raise an HTTPError exception if the status code indicates an error (4xx or 5xx).

Answer

Use a decorator on the request function

Answer

Check response.error

Answer

The library raises an exception by default

Question 20

A Python developer is writing a function that reads a configuration file and returns a dictionary. They want to follow PEP 8 and best practices for function design and documentation. Which two of the following should they do? (Choose two.)

Accepted Answer

Include a docstring that describes the function's purpose, parameters, and return value.. Following PEP 8 and best practices, function names should be descriptive and use lowercase with underscores, and public functions should have docstrings that explain their purpose, parameters, and return values. These practices enhance code readability and maintainability. The other options either use unclear parameter names, raise overly broad exceptions, or misplace the function relative to imports, all of which violate established conventions.

Answer

Place the function at the top of the file, before any imports, to make it easily accessible.

Answer

Raise a generic `Exception` if the file cannot be read, to keep error handling simple.

Answer

Use a single-letter parameter name like `f` for the file path to keep the signature short.