Testing Exceptions#
We will delve into testing for exceptions in Python using pytest. As developers, we strive to write resilient code that can handle all possible scenarios. A robust code should be designed to handle exceptions effectively. Exceptions are unexpected events or errors that might occur during the execution of a program, and they can disrupt the normal flow of code execution. By properly handling exceptions, we can prevent crashes and unexpected behaviors and ensure that the code continues to operate gracefully.
Let's take a step back and understand what context managers and exceptions in Python are.
Context managers#
Context managers in Python are a way to manage resources like files, network connections, and databases in an efficient manner (pythonic way).
They ensure that resources are properly acquired and releases, no matter what.
The with statement in Python is commonly used with context managers.
It allows us to define a block of code that uses a resource and automatically handles the release of resource.
# Opening a file using context manager
with open("file.txt", "r") as file:
data = file.read()
print(data)
Exceptions#
Exceptions in Python are events that occur during the execution of program and disrupt the normal flow of code execution.
They are raised when an error or exceptional conditions occur in the program, such as invalid operation, unexpected input, or a runtime error.
Exceptions are Python's way of handling errors and providing a mechanism to handle them gracefully. It's very important aspect of writing robust and reliable Python code.
Exceptions in Python can be raised explicitly using the raise statement or automatically raised by the Python interpreter when it encounters an error condition.
def divide_number(a, b):
try:
result = a / b
except ZeroDivisionError:
print("Error: Division by zero is not allowed!")
else:
return result
print(divide_numbers(10, 2)) # Output: 5.0
print(divide_numbers(10, 0)) # Output: Error: Division by zero is not allowed!
Python provides a variety of built-in exceptions that cover a wide range of error conditions, such as: TypeError, ValueError, FileNotFoundError, etc
Check it out#
- Let's see below
division.pyand its test case.
def divide_numbers(a, b):
if b == 0:
raise ZeroDivisionError("Cannot divide by zero")
return a / b
import pytest
from division import divide_numbers
def test_divide_numbers():
with pytest.raises(ZeroDivisionError):
divide_numbers(10, 0)
- to test it out, run
docker build -t pytest-exceptions docs/learning-python/unit-testing/exceptions/ && docker run pytest-exceptions