Pytest fixture conventions

Standardize tests on pytest and follow its conventions for structure and fixtures. Place tests in a tests/ directory without an __init__.py (pytest treats it as a plain directory, not a package), and name test files test_*.py so they are auto-discovered. For setup/teardown logic, prefer yield fixtures over request.addfinalizer, since they are more concise and keep setup and teardown code together:

import os
import tempfile
import pytest
from flaskr import flaskr

@pytest.fixture
def client():
    db_fd, flaskr.app.config['DATABASE'] = tempfile.mkstemp()
    flaskr.app.config['TESTING'] = True
    client = flaskr.app.test_client()
    with flaskr.app.app_context():
        flaskr.init_db()

    yield client

    os.close(db_fd)
    os.unlink(flaskr.app.config['DATABASE'])

Additionally, configure the test runner (e.g. tox.ini) to run py.test with coverage reporting enabled (--cov=<package> --cov-report html) and keep the ability to pass through extra arguments (e.g. py.test {posargs}) so individual tests can be targeted from the command line.