tools/test/test_trailing_newlines.py

from tools.linter import trailing_newlines
import unittest
import tempfile


def correct_trailing_newlines(file_contents: str) -> bool:
    with tempfile.NamedTemporaryFile(mode="w", delete=False) as tmp:
        filename = tmp.name
        tmp.write(file_contents)
    return trailing_newlines.correct_trailing_newlines(filename)


class TestTrailingNewlines(unittest.TestCase):
    def test_empty(self) -> None:
        self.assertTrue(correct_trailing_newlines(""))

    def test_single_byte(self) -> None:
        self.assertFalse(correct_trailing_newlines("a"))

    def test_single_newline(self) -> None:
        self.assertFalse(correct_trailing_newlines("\n"))

    def test_two_newlines(self) -> None:
        self.assertFalse(correct_trailing_newlines("\n\n"))

    def test_three_newlines(self) -> None:
        self.assertFalse(correct_trailing_newlines("\n\n\n"))

    def test_hello_world(self) -> None:
        self.assertFalse(correct_trailing_newlines("hello world"))

    def test_hello_world_newline(self) -> None:
        self.assertTrue(correct_trailing_newlines("hello world\n"))

    def test_hello_world_two_newlines(self) -> None:
        self.assertFalse(correct_trailing_newlines("hello world\n\n"))

    def test_hello_world_three_newlines(self) -> None:
        self.assertFalse(correct_trailing_newlines("hello world\n\n\n"))

    def test_hello_world_multiline(self) -> None:
        self.assertFalse(correct_trailing_newlines("hello\nworld"))

    def test_hello_world_multiline_gap(self) -> None:
        self.assertTrue(correct_trailing_newlines("hello\n\nworld\n"))


if __name__ == "__main__":
    unittest.main()