First install pytest: pip install pytest; 2. Write the code under test add and divide functions; 3. Write the test file to include normal tests, exception tests and parameterized tests; 4. Use the pytest -v command to run the test; 5. Optionally install pytest-cov to view the test coverage. This example fully demonstrates the basic usage of pytest, which is suitable for beginners to quickly get started and understand the testing process.
Below is a simple and practical Python pytest example, suitable for beginners to get started quickly. It shows how to write test cases, use assertions, test exceptions, and simple parameterized tests.
? 1. Install pytest
If you haven't installed pytest yet, run it first:
pip install pytest
? 2. The code being tested ( math_utils.py )
Create a file math_utils.py with a simple addition function:
# math_utils.py
def add(a, b):
return ab
def divide(a, b):
if b == 0:
raise ValueError("Cannot divide by zero")
return a / b ? 3. Write test files ( test_math_utils.py )
Create a test file test_math_utils.py :
# test_math_utils.py
import pytest
from math_utils import add, divide
# Test the add function def test_add():
assert add(2, 3) == 5
assert add(-1, 1) == 0
assert add(0, 0) == 0
# Test the normal situation of the divide function def test_divide():
assert divide(10, 2) == 5
assert divide(9, 3) == 3
# Test divide throws exception def test_divide_by_zero():
with pytest.raises(ValueError, match="Cannot divide by zero"):
divide(10, 0)
# Parameterized test: test the add function with multiple inputs @pytest.mark.parametrize("a, b, expected", [
(2, 3, 5),
(-1, 1, 0),
(0, 0, 0),
(100, -50, 50),
])
def test_add_parametriized(a, b, expected):
assert add(a, b) == expected? 4. Run the test
Run in the terminal:
pytest test_math_utils.py -v
The output is similar:
test_math_utils.py::test_add PASSED test_math_utils.py::test_divide PASSED test_math_utils.py::test_divide_by_zero PASSED test_math_utils.py::test_add_parametriized[2-3-5] PASSED test_math_utils.py::test_add_parametriized[-1-1-0] PASSED ...
Adding -v is to display detailed results.
? 5. Common tips
-
assert: pytest uses nativeassert, and the variable value will be automatically displayed when it fails. -
pytest.raises(): used to test whether the function throws the specified exception. -
@pytest.mark.parametrize: Avoid writing repeated test cases and batch test different inputs. - The test file name and function name must start with
test_, which is the pytest convention.
? 6. Optional: Test coverage (advanced)
Install pytest-cov to view test coverage:
pip install pytest-cov pytest --cov=math_utils test_math_utils.py
Basically that's it. Writing tests is not complicated, the key is to develop habits. pytest is simple and powerful, suitable for small projects to large applications.
The above is the detailed content of python pytest example. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
VSCode settings.json location
Aug 01, 2025 am 06:12 AM
The settings.json file is located in the user-level or workspace-level path and is used to customize VSCode settings. 1. User-level path: Windows is C:\Users\\AppData\Roaming\Code\User\settings.json, macOS is /Users//Library/ApplicationSupport/Code/User/settings.json, Linux is /home//.config/Code/User/settings.json; 2. Workspace-level path: .vscode/settings in the project root directory
How to handle transactions in Java with JDBC?
Aug 02, 2025 pm 12:29 PM
To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.
Mastering Dependency Injection in Java with Spring and Guice
Aug 01, 2025 am 05:53 AM
DependencyInjection(DI)isadesignpatternwhereobjectsreceivedependenciesexternally,promotingloosecouplingandeasiertestingthroughconstructor,setter,orfieldinjection.2.SpringFrameworkusesannotationslike@Component,@Service,and@AutowiredwithJava-basedconfi
Python for Data Engineering ETL
Aug 02, 2025 am 08:48 AM
Python is an efficient tool to implement ETL processes. 1. Data extraction: Data can be extracted from databases, APIs, files and other sources through pandas, sqlalchemy, requests and other libraries; 2. Data conversion: Use pandas for cleaning, type conversion, association, aggregation and other operations to ensure data quality and optimize performance; 3. Data loading: Use pandas' to_sql method or cloud platform SDK to write data to the target system, pay attention to writing methods and batch processing; 4. Tool recommendations: Airflow, Dagster, Prefect are used for process scheduling and management, combining log alarms and virtual environments to improve stability and maintainability.
How to work with Calendar in Java?
Aug 02, 2025 am 02:38 AM
Use classes in the java.time package to replace the old Date and Calendar classes; 2. Get the current date and time through LocalDate, LocalDateTime and LocalTime; 3. Create a specific date and time using the of() method; 4. Use the plus/minus method to immutably increase and decrease the time; 5. Use ZonedDateTime and ZoneId to process the time zone; 6. Format and parse date strings through DateTimeFormatter; 7. Use Instant to be compatible with the old date types when necessary; date processing in modern Java should give priority to using java.timeAPI, which provides clear, immutable and linear
Understanding the Java Virtual Machine (JVM) Internals
Aug 01, 2025 am 06:31 AM
TheJVMenablesJava’s"writeonce,runanywhere"capabilitybyexecutingbytecodethroughfourmaincomponents:1.TheClassLoaderSubsystemloads,links,andinitializes.classfilesusingbootstrap,extension,andapplicationclassloaders,ensuringsecureandlazyclassloa
Google Chrome cannot open local files
Aug 01, 2025 am 05:24 AM
ChromecanopenlocalfileslikeHTMLandPDFsbyusing"Openfile"ordraggingthemintothebrowser;ensuretheaddressstartswithfile:///;2.SecurityrestrictionsblockAJAX,localStorage,andcross-folderaccessonfile://;usealocalserverlikepython-mhttp.server8000tor
Comparing Java Frameworks: Spring Boot vs Quarkus vs Micronaut
Aug 04, 2025 pm 12:48 PM
Pre-formanceTartuptimeMoryusage, Quarkusandmicronautleadduetocompile-Timeprocessingandgraalvsupport, Withquarkusoftenperforminglightbetterine ServerLess scenarios.2.Thyvelopecosyste,
