Testing

Setting up testing with pytest and uv

Creating a Project with Tests

uv init myapp --package
d myapp

This creates a Python package project with the following structure:

myapp/
├── pyproject.toml
├── README.md
└── src
    └── myapp
        └── __init__.py

Adding pytest as a Development Dependency

Add pytest to your project’s development dependencies:

uv add --dev pytest

This command:

• Updates your pyproject.toml with pytest as a development dependency

• Create the project’s lockfile

• Installs pytest in your project’s virtual environment

Creating a Simple Module to Test

Let’s create a simple calculator module to test. Create a new file at src/myapp/calculator.py:

def add(a, b):
    return a + b


def subtract(a, b):
    return a - b


def multiply(a, b):
    return a * b


def divide(a, b):
    if b == 0:
        raise ValueError("Cannot divide by zero")
    return a / b

Creating Test Files

Create a tests directory at the root of your project

Now, create a test file for our calculator module in tests/test_calculator.py:

import pytest
from myapp.calculator import add, subtract, multiply, divide


def test_add():
    assert add(1, 2) == 3
    assert add(-1, 1) == 0
    assert add(-1, -1) == -2


def test_subtract():
    assert subtract(3, 2) == 1
    assert subtract(2, 3) == -1
    assert subtract(0, 0) == 0


def test_multiply():
    assert multiply(2, 3) == 6
    assert multiply(-2, 3) == -6
    assert multiply(-2, -3) == 6


def test_divide():
    assert divide(6, 3) == 2
    assert divide(6, -3) == -2
    assert divide(-6, -3) == 2


def test_divide_by_zero():
    with pytest.raises(ValueError):
        divide(5, 0)

Configuring pytest

Let’s configure pytest in your pyproject.toml file by adding these settings:

[tool.pytest.ini_options]
log_cli = true
testpaths = ["tests"]
python_files = "test_*.py"
python_functions = "test_*"
addopts = ["-v", "--strict-markers"]
pythonpath = ["."]

This configuration:

• Sets the test discovery path to the tests directory

• Specifies that test files should start with test_

• Specifies that test functions should start with test_

Running Tests

Now you can run your tests using uv:

uv run pytest

To see more detailed output, use the verbose flag:

uv run pytest --cov=testing_demo

For a more detailed report:

uv run pytest --cov=testing_demo --cov-report=term-missing

To test a specific test case in a test file

uv run pytest tests/integration/agent/test_basic.py::test_basic