"""Unittests for the check_env function."""

import os
import unittest

from pytohn_utils import check_env


class TestCheckEnv(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        """Set up test environment variables."""
        cls.set_vars = ["A", "B", "C"]
        for var in cls.set_vars:
            os.environ[var] = f"value_{var.lower()}"
        cls.unset_var = "D"
        if os.getenv(cls.unset_var) is not None:
            raise unittest.SkipTest(
                f"Environment variable '{cls.unset_var}' should not be set for this test."
            )

    @classmethod
    def tearDownClass(cls):
        for var in cls.set_vars:
            if var in os.environ:
                del os.environ[var]
            os.environ.pop(var, None)

    def test_check_env_accepts_single_string(self):
        """Test check_env function with a valid single string."""
        self.assertIsNone(check_env(self.set_vars[0]))

    def test_check_env_accepts_list_of_strings(self):
        """Test check_env function with a valid list of strings."""
        self.assertIsNone(check_env(self.set_vars))

    def test_check_env_accepts_set_of_strings(self):
        """Test check_env function with a valid set of strings."""
        self.assertIsNone(check_env(set(self.set_vars)))

    def test_check_env_accepts_tuple_of_strings(self):
        """Test check_env function with a valid tuple of strings."""
        self.assertIsNone(check_env(tuple(self.set_vars)))

    def test_check_env_rejects_empty_list(self):
        """Test check_env function with an empty list."""
        with self.assertRaises(ValueError):
            check_env([])

    def test_check_env_raises_error_on_missing_vars(self):
        """Test check_env function with missing environment variables."""
        with self.assertRaises(OSError):
            check_env(self.unset_var)

    def test_check_env_does_not_raise_error_when_missing_ok_flag_set(self):
        """Test that check_env does not raise an error when the environment variable is missing and missing_ok=True.

        The 'missing_ok' flag allows the function to skip raising an error if the specified environment variable(s) are not set.
        """
        self.assertIsNone(check_env(self.unset_var, missing_ok=True))