"""Tests for the FilenameOnly formatter object."""
import argparse

from flake8 import style_guide
from flake8.formatting import default


def options(**kwargs):
    """Create an argparse.Namespace instance."""
    kwargs.setdefault('output_file', None)
    kwargs.setdefault('tee', False)
    return argparse.Namespace(**kwargs)


def test_caches_filenames_already_printed():
    """Verify we cache filenames when we format them."""
    formatter = default.FilenameOnly(options())
    assert formatter.filenames_already_printed == set()

    formatter.format(
        style_guide.Violation('code', 'file.py', 1, 1, 'text', 'l'))
    assert formatter.filenames_already_printed == {'file.py'}


def test_only_returns_a_string_once_from_format():
    """Verify format ignores the second error with the same filename."""
    formatter = default.FilenameOnly(options())
    error = style_guide.Violation('code', 'file.py', 1, 1, 'text', '1')

    assert formatter.format(error) == 'file.py'
    assert formatter.format(error) is None


def test_show_source_returns_nothing():
    """Verify show_source returns nothing."""
    formatter = default.FilenameOnly(options())
    error = style_guide.Violation('code', 'file.py', 1, 1, 'text', '1')

    assert formatter.show_source(error) is None