Testing LIBFT functions using Python CFFI

test_gnl.py

##!/usr/bin/env python3

import pathlib
import tempfile
import unittest

import cffi

# You must compile a libft shared library
LIBFT_PATH = pathlib.Path("libft.so").absolute()


class TestGetNextLine(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        cls.ffi = cffi.FFI()
 
        # Load Lbift shared library
        cls.libft = cls.ffi.dlopen(LIBFT_PATH.as_posix(), cls.ffi.RTLD_NOW)

        # Define symbols we are going to use in our tests!
        cls.ffi.cdef("char *get_next_line(int fd);")

    @classmethod
    def tearDownClass(cls):
        cls.ffi.dlclose(cls.libft)

    def test_invalid_fd_returns_null(self):
        line = self.libft.get_next_line(-1)

        assert line == self.ffi.NULL

    def test_unused_fd_returns_null(self):
        line = self.libft.get_next_line(63)

        assert line == self.ffi.NULL

    def test_valid_empty_file_returns_null(self):
        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()

            line = self.libft.get_next_line(fd)

        assert line == self.ffi.NULL

    def test_valid_file_with_nl_returns_nl(self):
        expected_line = b"\n"

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("\n")
            temp_file.seek(0)

            line = self.libft.get_next_line(fd)

        assert self.ffi.string(line) == expected_line

    def test_valid_file_with_text_no_nl_returns_text(self):
        expected_line = b"Hello, World!"

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("Hello, World!")
            temp_file.seek(0)

            line = self.libft.get_next_line(fd)

        assert self.ffi.string(line) == expected_line

    def test_valid_file_with_text_with_nl_returns_line(self):
        expected_line = b"Hello, World!\n"

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("Hello, World!\n")
            temp_file.seek(0)

            line = self.libft.get_next_line(fd)

        assert self.ffi.string(line) == expected_line

    def test_valid_file_with_multiline_text_no_last_nl_returns_line(self):
        expected_lines = [
            b"Hello, World!\n",
            b"This is a test!",
        ]

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("Hello, World!\nThis is a test!")
            temp_file.seek(0)

            first_line = self.libft.get_next_line(fd)
            second_line = self.libft.get_next_line(fd)
            eof = self.libft.get_next_line(fd)

        assert self.ffi.string(first_line) == expected_lines[0]
        assert self.ffi.string(second_line) == expected_lines[1]
        assert eof == self.ffi.NULL

    def test_valid_file_with_multiline_text_with_last_nl_returns_line(self):
        expected_lines = [
            b"Hello, World!\n",
            b"This is a test!\n",
        ]

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("Hello, World!\nThis is a test!\n")
            temp_file.seek(0)

            first_line = self.libft.get_next_line(fd)
            second_line = self.libft.get_next_line(fd)
            eof = self.libft.get_next_line(fd)

        assert self.ffi.string(first_line) == expected_lines[0]
        assert self.ffi.string(second_line) == expected_lines[1]
        assert eof == self.ffi.NULL, self.ffi.string(eof)

    def test_big_file_just_for_the_lulz(self):
        lines = list()
        expected_lines = [b"NewLine\n" for _ in range(42)]
        expected_lines.append(b"NoNewLine")

        with tempfile.TemporaryFile(mode="r+") as temp_file:
            fd = temp_file.fileno()
            temp_file.write("NewLine\n" * 42 + "NoNewLine")
            temp_file.seek(0)

            while True:
                line = self.libft.get_next_line(fd)
                if line != self.ffi.NULL:
                    lines.append(line)
                else:
                    break

        for line, expected_line in zip(lines, expected_lines):
            assert self.ffi.string(line) == expected_line


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