PCPP1 Practice Test 18 — 15 Questions

Question 1

A Python script consumes a REST endpoint that returns a JSON document. You call response = requests.get(url) and want to convert the body into native Python objects. The response is guaranteed to be valid JSON. Which expression gives you the deserialized data?

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

Accepted Answer

response.json(). A requests Response exposes a json method that parses the body with the standard library's JSON decoder and returns native Python types. The text and content attributes expose the body as a string or bytes respectively, and json.load expects a file-like object, so none of those directly yield deserialized data.

Answer

response.content

Answer

response.text

Answer

json.load(response)

Question 2

When using configparser, how do you retrieve a value as a boolean?

Accepted Answer

parser.getboolean('section', 'option'). The getboolean() method converts common truthy/falsy values automatically.

Answer

parser.get('section', 'option', type=bool)

Answer

parser.get_bool('section', 'option')

Answer

bool(parser.get('section', 'option'))

Question 3

A developer is reviewing a pull request where a function uses a global variable to track a counter. The reviewer suggests refactoring to avoid global state. Which refactoring best follows best practices for maintainability and testability?

Accepted Answer

Encapsulate the counter in a class and use an instance variable.. Encapsulating state in a class instance eliminates global mutable state, making the code more modular and testable. Each instance has its own counter, and interactions are explicit. Passing the counter as an argument is also valid but can be less convenient for complex state. Using module-level globals or mutable defaults perpetuates the issues of shared state.

Answer

Pass the counter as an argument and return the updated value.

Answer

Use a default mutable argument to store the counter.

Answer

Use a module-level variable and declare it global inside the function.

Question 4

In the 'requests' library, which HTTP method is typically used to update an existing resource on a server?

Accepted Answer

PUT. The PUT method is standard for replacing or updating an existing resource at a specific URI.

Answer

POST

Answer

GET

Answer

DELETE

Question 5

You are developing a Tkinter application that includes a Button widget. When the user clicks the button, you need to execute a function named handle_click that accepts no arguments. Which approach correctly associates this function with the button's click event?

Accepted Answer

button = Button(root, text='Click', command=handle_click). The command option of a Tkinter Button expects a callable object that will be invoked when the button is clicked. Passing the function name without parentheses provides that callable. Using parentheses calls the function immediately, a lambda that returns the function does not call it, and a string is not callable. Therefore, the only correct approach is to pass the function object itself.

Answer

button = Button(root, text='Click', command='handle_click')

Answer

button = Button(root, text='Click', command=lambda: handle_click)

Answer

button = Button(root, text='Click', command=handle_click())

Question 6

A teammate writes a `Money` value object that defines `__eq__` to compare amounts and currencies, and `__hash__` to hash the same two fields. During a code review you notice that a subclass `Discount` adds a `percentage` field, overrides only `__eq__` to include that field, and leaves `__hash__` inherited. Objects of `Discount` are then used as dictionary keys. What is the actual runtime consequence?

Accepted Answer

Because `Discount` defines `__eq__`, Python sets `Discount.__hash__` to `None` in that class, so instances become unhashable and dictionary insertion raises `TypeError`.. Python enforces an invariant between equality and hashing: if a class overrides `__eq__`, the default identity hash is no longer consistent with the new equality, so the interpreter sets `__hash__` to `None` in that class. Defining `__eq__` in `Discount` without a matching `__hash__` makes its instances unhashable, and inheritance from `Money` does not restore hashability. Dictionary keys must therefore be plain `Money` objects or the subclass must define its own `__hash__`.

Answer

Python raises a `SyntaxError` at class-definition time because overriding `__eq__` without also overriding `__hash__` is statically rejected by the compiler.

Answer

The dictionary works correctly because `dict` uses `id()`-based hashing for user-defined classes whenever `__hash__` is ambiguous, sidestepping the overridden `__eq__`.

Answer

The inherited `Money.__hash__` is used, and because it hashes only amount and currency, two `Discount` objects with different percentages but equal amount and currency collide into one dictionary entry.

Question 7

Which TWO of the following are valid ways to add padding to a widget in the grid layout?

Accepted Answer

padx=10. In Tkinter's grid geometry manager, external padding around a widget is set with the padx and pady options, so option D (padx=10) adds 10 pixels of horizontal padding and option E (pady=10) adds 10 pixels of vertical padding to the widget's cell. These are the standard grid() parameters for per-widget padding, e.g., widget.grid(row=0, column=0, padx=10, pady=10). Option A (margin=10) is not a recognized Tkinter geometry option, and option B (spacing=10) is not a valid grid() parameter either. Option C (gap=10) is likewise not a Tkinter grid option; internal padding between widgets in a container is instead controlled by the container's padx/pady or by grid's ipadx/ipady for internal widget padding, not by a 'gap' keyword.

Answer

margin=10

Answer

spacing=10

Answer

gap=10

Question 8

You are using the `json` module to serialize a custom object that contains a `datetime.date` attribute. When you call `json.dumps(obj)`, you get a `TypeError: Object of type date is not JSON serializable`. Which approach correctly allows serialization while preserving the date as an ISO 8601 string?

Accepted Answer

Create a subclass of `json.JSONEncoder` and override its `default` method to return `obj.isoformat()` for `date` instances, then pass it to `json.dumps` via the `cls` parameter.. The `json` module's `JSONEncoder` class provides a `default` method that is called for objects that are not natively serializable. By subclassing and overriding this method, you can return a serializable representation, such as an ISO 8601 string for dates. Passing this encoder class to `json.dumps` via the `cls` argument enables the custom behavior.

Answer

Implement a `__json__` method on the custom object that returns a serializable dictionary, and `json.dumps` will call it automatically.

Answer

Use `json.dumps(obj, default=str)` to automatically convert any non-serializable object to its string representation.

Answer

Convert the `date` attribute to a string using `obj.date.isoformat()` before calling `json.dumps`, and then convert it back when deserializing.

Question 9

When overriding the __getattr__ method, what must you be careful to avoid?

Accepted Answer

Infinite recursion by accessing non-existent attributes.. Infinite recursion occurs if you try to access an attribute inside __getattr__ that does not exist, triggering __getattr__ again.

Answer

Raising AttributeError.

Answer

Accessing class attributes.

Answer

Calling super().__getattr__.

Question 10

You are writing a script that reads a large CSV file using csv.reader. The file uses a semicolon as the delimiter and contains quoted fields with embedded newlines. Which instantiation correctly handles this format?

Accepted Answer

csv.reader(file, delimiter=';', quotechar='"'). The csv.reader requires the correct delimiter and quotechar to parse a file with semicolon-separated values and quoted fields containing newlines. Setting delimiter to ';' and quotechar to '"' ensures that embedded newlines within quotes are treated as part of the field. Disabling quoting or using the wrong delimiter breaks parsing, and an escapechar alone does not address quoted newlines.

Answer

csv.reader(file, delimiter=';', quoting=csv.QUOTE_NONE)

Answer

csv.reader(file, delimiter=',', quotechar='"')

Answer

csv.reader(file, delimiter=';', escapechar='\')

Question 11

Which THREE of the following steps are required to initialize a TCP server socket?

Accepted Answer

Create a socket with socket.AF_INET and socket.SOCK_STREAM. Option A is correct because a TCP server must first create a stream socket using socket.AF_INET for IPv4 addressing and socket.SOCK_STREAM for TCP, which establishes the endpoint that will later be bound and listened on. Option C is correct because after binding, the server must call listen() to put the socket into passive mode so it can accept incoming connection requests, which is what makes it a listening server socket. Option E is correct because bind() associates the socket with a specific local IP address and port, which is required before the socket can listen for connections on that address. Option B is incorrect because connect() is used by a client to initiate a connection to a server, not by a server to start listening. Option D is incorrect because recv() is used to receive data on an already-connected socket and cannot be called before bind() during server initialization.

Answer

Call connect() to start the server

Answer

Call recv() before bind()

Question 12

Which TWO practices help maintain clean code when using Python's 'try-except' blocks?

Accepted Answer

Keep the 'try' block as small as possible.. Option A is correct because keeping the 'try' block as small as possible limits it to only the statements that can actually raise the expected exception, which makes the source of an error obvious and prevents unrelated bugs from being accidentally caught and masked. Option D is correct because Python evaluates 'except' clauses in order, so catching the most specific exception classes first (for example 'except ValueError:' before 'except Exception:') ensures precise handling and prevents a broad handler from shadowing a more specific one. Option B is wrong because a single bare 'except:' for the whole project swallows every exception, including 'KeyboardInterrupt' and 'SystemExit', and hides real defects. Option C is wrong because silently ignoring errors in the 'except' block discards diagnostic information and lets the program continue in an invalid state. Option E is wrong because putting as much code as possible in the 'try' block widens the scope of what can be caught, making it unclear which statement raised the exception and increasing the chance of masking unrelated errors.

Answer

Use a single 'except:' clause for the whole project.

Answer

Always ignore errors in the 'except' block.

Answer

Put as much code as possible in the 'try' block.

Question 13

You are writing a Python application that must parse a configuration file where a value spans multiple lines, such as a long list of email addresses separated by newlines. You decide to use the configparser module. Which of the following correctly describes how to include a multi-line value in the configuration file?

Accepted Answer

Indent continuation lines with whitespace; they will be joined with newline characters.. In configparser, multi-line values are specified by indenting continuation lines. The parser then joins these lines with newline characters. This is the standard way to include values that span multiple lines, such as lists. The other options incorrectly suggest backslashes, triple quotes, or semicolons, which are not part of the INI format syntax for continuation.

Answer

Separate lines with a semicolon to indicate continuation.

Answer

Enclose the value in triple quotes to allow multiple lines.

Answer

Use a backslash at the end of each line to indicate continuation.

Question 14

A developer creates a class named `Registry` in a module. The class inherits from `ABCMeta` and defines a `__new__` method that performs validation on the class namespace before the class is created. Inside `__new__`, the developer needs to inspect the attributes defined in the class body of the class being created. Which parameter of `__new__` provides direct access to those attributes?

Accepted Answer

The `namespace` parameter.. The namespace dictionary is the fourth positional argument supplied to `ABCMeta.__new__`. It holds every name bound in the class body before the class object exists, which is exactly the data needed for validation during class creation. The other parameters describe the metaclass, the parent tuple, or extra keywords, none of which carry class-body attributes.

Answer

The `bases` parameter.

Answer

The `**kwargs` parameter.

Answer

The `mcls` parameter.

Question 15

When using a metaclass, how can you access the class attributes during the class definition?

Accepted Answer

By accessing the namespace dictionary passed to __new__.. The class dictionary passed to the metaclass's __new__ method contains all the attributes defined within the class body.

Answer

By calling super().

Answer

By accessing the class __dict__.

Answer

By querying the base class.