Default unit test session.

def default(session, django_dep=('django',)):
    """Default unit test session.
    """

    # Install all test dependencies, then install this package in-place.
    deps = UNIT_TEST_DEPS
    deps += django_dep

    session.install(*deps)
    for local_dep in LOCAL_DEPS:
        session.install('-e', local_dep)
    session.install('-e', '.')

    # Run py.test against the unit tests.
    session.run(
        'py.test',
        '--quiet',
        '--cov=google.cloud.logging',
        '--cov=tests.unit',
        '--cov-append',
        '--cov-config=.coveragerc',
        '--cov-report=',
        '--cov-fail-under=97',
        'tests/unit',
        *session.posargs
    )