from contextlib import contextmanager
import os
from unittest import expectedFailure, TestSuite, TextTestRunner, defaultTestLoader

from django.test import TestCase
from django.test.runner import DiscoverRunner


def expectedFailureIf(condition):
    """Marks a test as an expected failure if ``condition`` is met."""
    if condition:
        return expectedFailure
    return lambda func: func


class DiscoverRunnerTest(TestCase):

    def test_dotted_test_module(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests_sample"],
        ).countTestCases()

        self.assertEqual(count, 2)

    def test_dotted_test_class_vanilla_unittest(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests_sample.TestVanillaUnittest"],
        ).countTestCases()

        self.assertEqual(count, 1)

    def test_dotted_test_class_django_testcase(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests_sample.TestDjangoTestCase"],
        ).countTestCases()

        self.assertEqual(count, 1)

    def test_dotted_test_method_django_testcase(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests_sample.TestDjangoTestCase.test_sample"],
        ).countTestCases()

        self.assertEqual(count, 1)

    def test_pattern(self):
        count = DiscoverRunner(
            pattern="*_tests.py",
        ).build_suite(["test_discovery_sample"]).countTestCases()

        self.assertEqual(count, 1)

    def test_file_path(self):
        @contextmanager
        def change_cwd_to_tests():
            """Change CWD to tests directory (one level up from this file)"""
            current_dir = os.path.abspath(os.path.dirname(__file__))
            tests_dir = os.path.join(current_dir, '..')
            old_cwd = os.getcwd()
            os.chdir(tests_dir)
            yield
            os.chdir(old_cwd)

        with change_cwd_to_tests():
            count = DiscoverRunner().build_suite(
                ["test_discovery_sample/"],
            ).countTestCases()

        self.assertEqual(count, 3)

    def test_empty_test_case(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests_sample.EmptyTestCase"],
        ).countTestCases()

        self.assertEqual(count, 0)

    def test_discovery_on_package(self):
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.tests"],
        ).countTestCases()

        self.assertEqual(count, 1)

    def test_ignore_adjacent(self):
        """
        When given a dotted path to a module, unittest discovery searches
        not just the module, but also the directory containing the module.

        This results in tests from adjacent modules being run when they
        should not. The discover runner avoids this behavior.
        """
        count = DiscoverRunner().build_suite(
            ["test_discovery_sample.empty"],
        ).countTestCases()

        self.assertEqual(count, 0)

    def test_overrideable_test_suite(self):
        self.assertEqual(DiscoverRunner().test_suite, TestSuite)

    def test_overrideable_test_runner(self):
        self.assertEqual(DiscoverRunner().test_runner, TextTestRunner)

    def test_overrideable_test_loader(self):
        self.assertEqual(DiscoverRunner().test_loader, defaultTestLoader)