How can one disregard a .env file while running tests with pytest when using Pydantic settings management and FastAPI?

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To disregard a .env file while running tests with pytest when using Pydantic settings management and FastAPI, you can use the env_override parameter while initializing the Settings class.

For example:

from pydantic import BaseSettings

class Settings(BaseSettings):
    api_key: str

    class Config:
        env_file = ".env"
        env_override = True

settings = Settings()

# Use the `env_override` parameter to override the `.env` file during tests
if __name__ == "__main__":
    import uvicorn
    uvicorn.run("myapp:app", host="0.0.0.0", port=8000, reload=True)

Then, in your pytest configuration, you can set an environment variable to override the .env file:

import os
from myapp.settings import Settings

def pytest_configure(config):
    config.addinivalue_line("markers", "integration: mark test as integration")
    settings = Settings(env_file="./.env.test", env_override=True)
    os.environ["API_KEY"] = settings.api_key

In this example, a .env.test file is used to set the environment variables for testing, and env_override is set to True to override the .env file. Finally, the API_KEY variable is set to the value in the settings object using os.environ.

This way, your tests will run with the API_KEY environment variable set to the value in the .env.test file, while disregarding the values from the .env file.