base_test_mixins.py

    @classmethod
    def get_single_grade_url(cls, participation_id, opp_id,
                             course_identifier=None):

        course_identifier = (
            course_identifier or cls.get_default_course_identifier())

        kwargs = {"course_identifier": course_identifier,
                  "opportunity_id": opp_id,
                  "participation_id": participation_id}

        return reverse("relate-view_single_grade", kwargs=kwargs)

    @classmethod
    def get_view_single_grade(cls, participation, gopp,
                             course_identifier=None, force_login_instructor=True):

        course_identifier = (
                course_identifier or cls.get_default_course_identifier())

        opp_id = GradingOpportunity.objects.get(
            course__identifier=course_identifier,
            identifier=gopp.identifier).pk

        if force_login_instructor:
            switch_to = cls.get_default_instructor_user(course_identifier)
        else:
            switch_to = cls.get_logged_in_user()

        with cls.temporarily_switch_to_user(switch_to):
            return cls.c.get(cls.get_single_grade_url(
                participation.pk, opp_id, course_identifier))

    @classmethod
    def post_view_single_grade(cls, participation, gopp, data,
                             course_identifier=None, force_login_instructor=True):

        course_identifier = (
                course_identifier or cls.get_default_course_identifier())

        opp_id = GradingOpportunity.objects.get(
            course__identifier=course_identifier,
            identifier=gopp.identifier).pk

        if force_login_instructor:
            switch_to = cls.get_default_instructor_user(course_identifier)
        else:
            switch_to = cls.get_logged_in_user()

        with cls.temporarily_switch_to_user(switch_to):
            return cls.c.post(cls.get_single_grade_url(
                participation.pk, opp_id, course_identifier),
                data=data)

    @classmethod
    def get_logged_in_user(cls):
        try:
            logged_in_user_id = cls.c.session['_auth_user_id']
            from django.contrib.auth import get_user_model
            logged_in_user = get_user_model().objects.get(
                pk=int(logged_in_user_id))
        except KeyError:
            logged_in_user = None
        return logged_in_user

    @classmethod
    def temporarily_switch_to_user(cls, switch_to):

        from functools import wraps

        class ClientUserSwitcher(object):
            def __init__(self, switch_to):
                self.client = cls.c
                self.switch_to = switch_to
                self.logged_in_user = cls.get_logged_in_user()

            def __enter__(self):
                if self.logged_in_user == self.switch_to:
                    return
                if self.switch_to is None:
                    self.client.logout()
                    return
                self.client.force_login(self.switch_to)

            def __exit__(self, exc_type, exc_val, exc_tb):
                if self.logged_in_user == self.switch_to:
                    return
                if self.logged_in_user is None:
                    self.client.logout()
                    return
                self.client.force_login(self.logged_in_user)

            def __call__(self, func):
                @wraps(func)
                def wrapper(*args, **kw):
                    with self:
                        return func(*args, **kw)
                return wrapper

        return ClientUserSwitcher(switch_to)

    @classmethod
    def get_default_course(cls):
        if Course.objects.count() > 1:
            raise AttributeError(
                "'course' arg can not be omitted for "
                "testcases with more than one courses")
        raise NotImplementedError

    @classmethod
    def get_default_course_identifier(cls):
        if Course.objects.count() > 1:
            raise AttributeError(
                "'course_identifier' arg can not be omitted for "
                "testcases with more than one courses")
        raise NotImplementedError

    @classmethod
    def get_latest_session_id(cls, course_identifier):
        flow_session_qset = FlowSession.objects.filter(
            course__identifier=course_identifier).order_by('-pk')[:1]
        if flow_session_qset:
            return flow_session_qset[0].id
        else:
            return None

    @classmethod
    def get_default_flow_session_id(cls, course_identifier):
        raise NotImplementedError

    @classmethod
    def update_default_flow_session_id(cls, course_identifier):
        raise NotImplementedError

    @classmethod
    def get_default_instructor_user(cls, course_identifier):
        return Participation.objects.filter(
            course__identifier=course_identifier,
            roles__identifier="instructor",
            status=participation_status.active
        ).first().user

    @classmethod
    def update_course_attribute(cls, attrs, course=None):
        # course instead of course_identifier because we need to do
        # refresh_from_db
        assert isinstance(attrs, dict)
        course = course or cls.get_default_course()
        if attrs:
            course.__dict__.update(attrs)
            course.save()
            course.refresh_from_db()

    @classmethod
    def get_view_start_flow_url(cls, flow_id, course_identifier=None):
        course_identifier = course_identifier or cls.get_default_course_identifier()
        kwargs = {"course_identifier": course_identifier,
                  "flow_id": flow_id}
        return reverse("relate-view_start_flow", kwargs=kwargs)

    @classmethod
    def start_flow(cls, flow_id, course_identifier=None,
                   ignore_cool_down=True, assume_success=True):
        """
        Notice: be cautious to use this in setUpTestData, because this will
        create many related objects in db, if those objects are changed in
        individual test, other tests followed might fail.
        """
        existing_session_count = FlowSession.objects.all().count()
        if ignore_cool_down:
            cool_down_seconds = 0
        else:
            cool_down_seconds = settings.RELATE_SESSION_RESTART_COOLDOWN_SECONDS
        with override_settings(
                RELATE_SESSION_RESTART_COOLDOWN_SECONDS=cool_down_seconds):
            resp = cls.c.post(
                cls.get_view_start_flow_url(flow_id, course_identifier))

        if assume_success:
            assert resp.status_code == 302, resp.content
            new_session_count = FlowSession.objects.all().count()
            assert new_session_count == existing_session_count + 1
            _, _, params = resolve(resp.url)
            del params["page_ordinal"]
            cls.default_flow_params = params
            cls.update_default_flow_session_id(course_identifier)

        return resp

    @classmethod
    def end_flow(cls, course_identifier=None, flow_session_id=None,
                 post_parameter="submit"):
        if not course_identifier or not flow_session_id:
            if cls.default_flow_params is None:
                raise RuntimeError(
                    "There's no started flow_sessions, or "
                    "the session is not started by start_flow")
        resp = cls.c.post(
            cls.get_finish_flow_session_view_url(
                course_identifier, flow_session_id),
            data={post_parameter: ['']})
        return resp

    @classmethod
    def get_resume_flow_url(cls, course_identifier=None, flow_session_id=None):
        flow_params = cls.get_flow_params(course_identifier, flow_session_id)
        return reverse("relate-view_resume_flow", kwargs=flow_params)

    @classmethod
    def get_flow_params(cls, course_identifier=None, flow_session_id=None):
        course_identifier = (
                course_identifier or cls.get_default_course_identifier())
        if flow_session_id is None:
            flow_session_id = cls.get_default_flow_session_id(course_identifier)
        return {
            "course_identifier": course_identifier,
            "flow_session_id": flow_session_id
        }

    @classmethod
    def get_page_params(cls, course_identifier=None, flow_session_id=None,
                        page_ordinal=None):
        page_params = cls.get_flow_params(course_identifier, flow_session_id)
        if page_ordinal is None:
            page_ordinal = 0
        page_params.update({"page_ordinal": page_ordinal})
        return page_params

    @classmethod
    def get_page_ordinal_via_page_id(
            cls, page_id, course_identifier=None, flow_session_id=None,
            with_group_id=False):
        flow_params = cls.get_flow_params(course_identifier, flow_session_id)
        return (
            get_flow_page_ordinal_from_page_id(
                flow_params["flow_session_id"], page_id,
                with_group_id=with_group_id))

    @classmethod
    def get_page_id_via_page_oridnal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None,
            with_group_id=False):
        flow_params = cls.get_flow_params(course_identifier, flow_session_id)
        return (
            get_flow_page_id_from_page_ordinal(
                flow_params["flow_session_id"], page_ordinal,
                with_group_id=with_group_id))

    @classmethod
    def get_page_view_url_by_ordinal(
            cls, viewname, page_ordinal, course_identifier=None,
            flow_session_id=None):
        page_params = cls.get_page_params(
            course_identifier, flow_session_id, page_ordinal)
        return reverse(viewname, kwargs=page_params)

    @classmethod
    def get_page_view_url_by_page_id(
            cls, viewname, page_id, course_identifier=None, flow_session_id=None):
        page_ordinal = cls.get_page_ordinal_via_page_id(
            page_id, course_identifier, flow_session_id)
        return cls.get_page_view_url_by_ordinal(
            viewname, page_ordinal, course_identifier, flow_session_id)

    @classmethod
    def get_page_url_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None,
            visit_id=None):
        url = cls.get_page_view_url_by_ordinal(
            "relate-view_flow_page",
            page_ordinal, course_identifier, flow_session_id)
        if visit_id is not None:
            url += "?visit_id=%s" % str(visit_id)

        return url

    @classmethod
    def get_page_url_by_page_id(
            cls, page_id, course_identifier=None, flow_session_id=None,
            visit_id=None):
        page_ordinal = cls.get_page_ordinal_via_page_id(
            page_id, course_identifier, flow_session_id)
        return cls.get_page_url_by_ordinal(
            page_ordinal, course_identifier, flow_session_id, visit_id)

    @classmethod
    def get_page_grading_url_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None):
        return cls.get_page_view_url_by_ordinal(
            "relate-grade_flow_page",
            page_ordinal, course_identifier, flow_session_id)

    @classmethod
    def get_page_grading_url_by_page_id(
            cls, page_id, course_identifier=None, flow_session_id=None):
        page_ordinal = cls.get_page_ordinal_via_page_id(
            page_id, course_identifier, flow_session_id)
        return cls.get_page_grading_url_by_ordinal(
            page_ordinal, course_identifier, flow_session_id)

    @classmethod
    def post_answer_by_ordinal(
            cls, page_ordinal, answer_data,
            course_identifier=None, flow_session_id=None, visit_id=None):
        submit_data = answer_data
        submit_data.update({"submit": ["Submit final answer"]})
        resp = cls.c.post(
            cls.get_page_url_by_ordinal(
                page_ordinal, course_identifier, flow_session_id, visit_id),
            submit_data)
        return resp

    @classmethod
    def post_answer_by_page_id(
            cls, page_id, answer_data,
            course_identifier=None, flow_session_id=None, visit_id=None):
        page_ordinal = cls.get_page_ordinal_via_page_id(
            page_id, course_identifier, flow_session_id)
        return cls.post_answer_by_ordinal(
            page_ordinal, answer_data, course_identifier, flow_session_id, visit_id)

    @classmethod
    def post_answer_by_ordinal_class(cls, page_ordinal, answer_data,
                                     course_identifier, flow_session_id):
        submit_data = answer_data
        submit_data.update({"submit": ["Submit final answer"]})
        page_params = {
            "course_identifier": course_identifier,
            "flow_session_id": flow_session_id,
            "page_ordinal": page_ordinal
        }
        page_url = reverse("relate-view_flow_page", kwargs=page_params)
        resp = cls.c.post(page_url, submit_data)
        return resp

    @classmethod
    def post_answer_by_page_id_class(cls, page_id, answer_data,
                                     course_identifier, flow_session_id):
        page_ordinal = get_flow_page_ordinal_from_page_id(flow_session_id, page_id)
        return cls.post_answer_by_ordinal_class(page_ordinal, answer_data,
                                                course_identifier, flow_session_id)

    @classmethod
    def post_grade_by_ordinal(cls, page_ordinal, grade_data,
                              course_identifier=None, flow_session_id=None,
                              force_login_instructor=True):
        post_data = {"submit": [""]}
        post_data.update(grade_data)

        page_params = cls.get_page_params(
            course_identifier, flow_session_id, page_ordinal)

        force_login_user = cls.get_logged_in_user()
        if force_login_instructor:
            force_login_user = cls.get_default_instructor_user(
                page_params["course_identifier"])

        with cls.temporarily_switch_to_user(force_login_user):
            response = cls.c.post(
                cls.get_page_grading_url_by_ordinal(**page_params),
                data=post_data,
                follow=True)
        return response

    @classmethod
    def post_grade_by_page_id(cls, page_id, grade_data,
                              course_identifier=None, flow_session_id=None,
                              force_login_instructor=True):
        page_ordinal = cls.get_page_ordinal_via_page_id(
            page_id, course_identifier, flow_session_id)

        return cls.post_grade_by_ordinal(
            page_ordinal, grade_data, course_identifier,
            flow_session_id, force_login_instructor)

    @classmethod
    def assertSessionScoreEqual(  # noqa
            cls, expected_score, course_identifier=None, flow_session_id=None):
        if flow_session_id is None:
            flow_params = cls.get_flow_params(course_identifier, flow_session_id)
            flow_session_id = flow_params["flow_session_id"]
        flow_session = FlowSession.objects.get(id=flow_session_id)
        if expected_score is not None:
            from decimal import Decimal
            assert flow_session.points == Decimal(str(expected_score)), (
                "The flow session got '%s' in stead of '%s'"
                % (str(flow_session.points), str(Decimal(str(expected_score))))
            )
        else:
            assert flow_session.points is None, (
                    "This flow session unexpectedly got %s instead of None"
                    % flow_session.points)

    @classmethod
    def get_page_submit_history_url_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None):
        return cls.get_page_view_url_by_ordinal(
            "relate-get_prev_answer_visits_dropdown_content",
            page_ordinal, course_identifier, flow_session_id)

    @classmethod
    def get_page_grade_history_url_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None):
        return cls.get_page_view_url_by_ordinal(
            "relate-get_prev_grades_dropdown_content",
            page_ordinal, course_identifier, flow_session_id)

    @classmethod
    def get_page_submit_history_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None):
        resp = cls.c.get(
            cls.get_page_submit_history_url_by_ordinal(
                page_ordinal, course_identifier, flow_session_id),
            HTTP_X_REQUESTED_WITH='XMLHttpRequest')
        return resp

    @classmethod
    def get_page_grade_history_by_ordinal(
            cls, page_ordinal, course_identifier=None, flow_session_id=None):
        resp = cls.c.get(
            cls.get_page_grade_history_url_by_ordinal(
                page_ordinal, course_identifier, flow_session_id),
            HTTP_X_REQUESTED_WITH='XMLHttpRequest')
        return resp

    def assertSubmitHistoryItemsCount(  # noqa
            self, page_ordinal, expected_count, course_identifier=None,
            flow_session_id=None):
        resp = self.get_page_submit_history_by_ordinal(
            page_ordinal, course_identifier, flow_session_id)
        import json
        result = json.loads(resp.content.decode())["result"]
        self.assertEqual(len(result), expected_count)

    def assertGradeHistoryItemsCount(  # noqa
            self, page_ordinal, expected_count,
            course_identifier=None,
            flow_session_id=None,
            force_login_instructor=True):

        if course_identifier is None:
            course_identifier = self.get_default_course_identifier()

        if force_login_instructor:
            switch_to = self.get_default_instructor_user(course_identifier)
        else:
            switch_to = self.get_logged_in_user()

        with self.temporarily_switch_to_user(switch_to):
            resp = self.get_page_grade_history_by_ordinal(
                page_ordinal, course_identifier, flow_session_id)

        import json
        result = json.loads(resp.content.decode())["result"]
        self.assertEqual(len(result), expected_count)

    @classmethod
    def get_update_course_url(cls, course_identifier=None):
        if course_identifier is None:
            course_identifier = cls.get_default_course_identifier()
        return reverse("relate-update_course", args=[course_identifier])

    @classmethod
    def get_course_commit_sha(cls, participation, course=None):
        course = course or cls.get_default_course()
        from course.content import get_course_commit_sha
        return get_course_commit_sha(course, participation)

    @classmethod
    def post_update_course_content(cls, commit_sha,
                                   prevent_discarding_revisions=True,
                                   force_login_instructor=True,
                                   course=None,
                                   command="update",
                                   ):
        # course instead of course_identifier because we need to do
        # refresh_from_db
        course = course or cls.get_default_course()

        try:
            commit_sha = commit_sha.decode()
        except Exception:
            pass

        data = {"new_sha": [commit_sha]}

        if not prevent_discarding_revisions:
            data["prevent_discarding_revisions"] = ["on"]

        # normally, command should be in
        # ["fetch", "fetch_update", "update", "fetch_preview", "preview",
        #  "end_preview"]
        data[command] = 'on'

        force_login_user = cls.get_logged_in_user()
        if force_login_instructor:
            force_login_user = cls.get_default_instructor_user(course.identifier)

        with cls.temporarily_switch_to_user(force_login_user):
            response = cls.c.post(
                cls.get_update_course_url(course.identifier), data)
            course.refresh_from_db()

        return response

    @classmethod
    def get_page_data_by_page_id(
            cls, page_id, course_identifier=None, flow_session_id=None):
        flow_params = cls.get_flow_params(course_identifier, flow_session_id)
        return FlowPageData.objects.get(
            flow_session_id=flow_params["flow_session_id"], page_id=page_id)

    @classmethod
    def get_page_visits(cls, course_identifier=None,
                        flow_session_id=None, page_ordinal=None, page_id=None,
                        **kwargs):
        query_kwargs = {}
        if kwargs.get("answer_visit", False):
            query_kwargs.update({"answer__isnull": False})
        flow_params = cls.get_flow_params(course_identifier, flow_session_id)
        query_kwargs.update({"flow_session_id": flow_params["flow_session_id"]})
        if page_ordinal is not None:
            query_kwargs.update({"page_data__page_ordinal": page_ordinal})
        elif page_id is not None:
            query_kwargs.update({"page_data__page_id": page_id})
        return FlowPageVisit.objects.filter(**query_kwargs)

    @classmethod
    def get_last_answer_visit(cls, course_identifier=None,
                              flow_session_id=None, page_ordinal=None,
                              page_id=None, assert_not_none=True):
        result_qset = cls.get_page_visits(course_identifier,
                                          flow_session_id, page_ordinal, page_id,
                                          answer_visit=True).order_by('-pk')[:1]
        if result_qset:
            result = result_qset[0]
        else:
            result = None
        if assert_not_none:
            assert result is not None, "The query returns None"
        return result

    @classmethod
    def download_all_submissions_url(cls, flow_id, course_identifier):
        params = {"course_identifier": course_identifier,
                  "flow_id": flow_id}
        return reverse("relate-download_all_submissions", kwargs=params)

    @classmethod
    def get_download_all_submissions(cls, flow_id, course_identifier=None):
        if course_identifier is None:
            course_identifier = cls.get_default_course_identifier()

        return cls.c.get(
            cls.download_all_submissions_url(flow_id, course_identifier))

    @classmethod
    def post_download_all_submissions_by_group_page_id(
            cls, group_page_id, flow_id, course_identifier=None, **kwargs):
        """
        :param group_page_id: format: group_id/page_id
        :param flow_id:
        :param course_identifier:
        :param kwargs: for updating the default post_data
        :return: response
        """
        if course_identifier is None:
            course_identifier = cls.get_default_course_identifier()

        data = {'restrict_to_rules_tag': '<<<ALL>>>',
                'which_attempt': 'last',
                'extra_file': '', 'download': 'Download',
                'page_id': group_page_id,
                'non_in_progress_only': 'on'}

        data.update(kwargs)

        return cls.c.post(
            cls.download_all_submissions_url(flow_id, course_identifier),
            data=data
        )

    @classmethod
    def get_flow_page_analytics(cls, flow_id, group_id, page_id,
                                course_identifier=None):
        if course_identifier is None:
            course_identifier = cls.get_default_course_identifier()

        params = {"course_identifier": course_identifier,
                  "flow_id": flow_id,
                  "group_id": group_id,
                  "page_id": page_id}

        return cls.c.get(reverse("relate-page_analytics", kwargs=params))

    # {{{ hack getting session rules

    default_session_start_rule = {
        "tag_session": None,
        "may_start_new_session": True,
        "may_list_existing_sessions": True,
        "default_expiration_mode": None}

    def get_hacked_session_start_rule(self, **kwargs):
        """
        Used for mocking session_start_rule
        :param kwargs: attributes in the mocked FlowSessionStartRule instance
        :return: a :class:`FlowSessionStartRule` instance

        Example:

            with mock.patch(
                "course.flow.get_session_start_rule") as mock_get_nrule:
                mock_get_nrule.return_value = (
                    self.get_hacked_session_start_rule())
        """
        from course.utils import FlowSessionStartRule
        defaults = deepcopy(self.default_session_start_rule)
        defaults.update(kwargs)
        return FlowSessionStartRule(**defaults)

    default_session_access_rule = {
        "permissions": [fperm.view, fperm.end_session]}

    def get_hacked_session_access_rule(self, **kwargs):
        """
        Used for mocking session_access_rule
        :param kwargs: attributes in the mocked FlowSessionAccessRule instance
        :return: a :class:`FlowSessionAccessRule` instance

        Example:

            with mock.patch(
                    "course.flow.get_session_access_rule") as mock_get_arule:
                mock_get_arule.return_value = (
                    self.get_hacked_session_access_rule(
                        permissions=[fperm.end_session]))
        """
        from course.utils import FlowSessionAccessRule
        defaults = deepcopy(self.default_session_access_rule)
        defaults.update(kwargs)
        return FlowSessionAccessRule(**defaults)

    default_session_grading_rule = {
        "grade_identifier": "la_quiz",
        "grade_aggregation_strategy": g_strategy.use_latest,
        "due": None,
        "generates_grade": True,
        "description": None,
        "credit_percent": 100,
        "use_last_activity_as_completion_time": False,
        "bonus_points": 0,
        "max_points": None,
        "max_points_enforced_cap": None,
    }

    def get_hacked_session_grading_rule(self, **kwargs):
        """
        Used for mocking session_grading_rule
        :param kwargs: attributes in the mocked FlowSessionGradingRule instance
        :return: a :class:`FlowSessionGradingRule` instance

        Example:

            with mock.patch(
                "course.flow.get_session_grading_rule") as mock_get_grule:
                mock_get_grule.return_value = \
                    self.get_hacked_session_grading_rule(bonus_points=2)
        """
        from course.utils import FlowSessionGradingRule
        defaults = deepcopy(self.default_session_grading_rule)
        defaults.update(kwargs)
        return FlowSessionGradingRule(**defaults)

    # }}}

    # {{{ grades view
    def view_participant_grades_url(self, participation_id, course_identifier=None):
        course_identifier = (
            course_identifier or self.get_default_course_identifier())
        kwargs = {"course_identifier": course_identifier}

        if participation_id is not None:
            kwargs["participation_id"] = participation_id

        return reverse("relate-view_participant_grades", kwargs=kwargs)

    def get_view_participant_grades(self, participation_id, course_identifier=None):
        return self.c.get(self.view_participant_grades_url(
            participation_id, course_identifier))

    def get_view_my_grades(self, course_identifier=None):
        return self.c.get(self.view_participant_grades_url(
            participation_id=None, course_identifier=course_identifier))

    # }}}


class SingleCourseTestMixin(CoursesTestMixinBase):
    courses_setup_list = SINGLE_COURSE_SETUP_LIST
    initial_commit_sha = None
    force_login_student_for_each_test = True

    @classmethod
    def setUpTestData(cls):  # noqa
        super(SingleCourseTestMixin, cls).setUpTestData()
        assert len(cls.course_qset) == 1
        cls.course = cls.course_qset.first()
        if cls.initial_commit_sha is not None:
            cls.course.active_git_commit_sha = cls.initial_commit_sha
            cls.course.save()

        cls.instructor_participation = Participation.objects.filter(
            course=cls.course,
            roles__identifier="instructor",
            status=participation_status.active
        ).first()
        assert cls.instructor_participation

        cls.student_participation = Participation.objects.filter(
            course=cls.course,
            roles__identifier="student",
            status=participation_status.active
        ).first()
        assert cls.student_participation

        cls.ta_participation = Participation.objects.filter(
            course=cls.course,
            roles__identifier="ta",
            status=participation_status.active
        ).first()
        assert cls.ta_participation

        if cls.force_login_student_for_each_test:
            cls.c.force_login(cls.student_participation.user)
        else:
            cls.c.logout()
        cls.course_page_url = cls.get_course_page_url()

    def setUp(self):  # noqa
        super(SingleCourseTestMixin, self).setUp()

        # reload objects created during setUpTestData in case they were modified in
        # tests. Ref: https://goo.gl/AuzJRC#django.test.TestCase.setUpTestData
        self.course.refresh_from_db()
        self.instructor_participation.refresh_from_db()
        self.student_participation.refresh_from_db()
        self.ta_participation.refresh_from_db()
        if self.force_login_student_for_each_test:
            self.c.force_login(self.student_participation.user)

    @classmethod
    def get_default_course(cls):
        return cls.course

    @classmethod
    def get_default_course_identifier(cls):
        return cls.get_default_course().identifier

    def copy_course_dict_and_set_attrs_for_post(self, attrs_dict={}):
        from course.models import Course
        kwargs = Course.objects.first().__dict__
        kwargs.update(attrs_dict)

        import six
        for k, v in six.iteritems(kwargs):
            if v is None:
                kwargs[k] = ""
        return kwargs

    def get_course_page_context(self, user):
        rf = RequestFactory()
        request = rf.get(self.get_course_page_url())
        request.user = user

        from course.utils import CoursePageContext
        pctx = CoursePageContext(request, self.course.identifier)
        return pctx

    def get_hacked_flow_desc(
            self, user=None, flow_id=None, commit_sha=None,
            del_rules=False, as_dict=False, **kwargs):
        """
        Get a hacked version of flow_desc
        :param user: the flow_desc viewed by which user, default to a student
        :param flow_id: the flow_desc of which flow_id, default to `quiz-test`
        :param commit_sha: default to corrent running commit_sha
        :param kwargs: the attributes of the hacked flow_dec
        :return: the faked flow_desc
        """

        # {{{ get the actual flow_desc by a real visit
        rf = RequestFactory()
        request = rf.get(self.get_course_page_url())
        if user is None:
            user = self.student_participation.user
        request.user = user

        if flow_id is None:
            flow_id = QUIZ_FLOW_ID

        if commit_sha is None:
            commit_sha = self.course.active_git_commit_sha

        if isinstance(commit_sha, six.text_type):
            commit_sha = commit_sha.encode()

        from course.content import get_flow_desc
        with self.get_course_page_context(user) as pctx:
            flow_desc = get_flow_desc(
                pctx.repo, pctx.course, flow_id, commit_sha)

        # }}}

        from relate.utils import struct_to_dict, dict_to_struct
        flow_desc_dict = struct_to_dict(flow_desc)

        if del_rules:
            del flow_desc_dict["rules"]

        flow_desc_dict.update(kwargs)

        if as_dict:
            return flow_desc_dict

        return dict_to_struct(flow_desc_dict)


class TwoCourseTestMixin(CoursesTestMixinBase):
    courses_setup_list = TWO_COURSE_SETUP_LIST

    @classmethod
    def setUpTestData(cls):  # noqa
        super(TwoCourseTestMixin, cls).setUpTestData()
        assert len(cls.course_qset) == 2, (
            "'courses_setup_list' should contain two courses")
        cls.course1 = cls.course_qset.first()
        cls.course1_instructor_participation = Participation.objects.filter(
            course=cls.course1,
            roles__identifier="instructor",
            status=participation_status.active
        ).first()
        assert cls.course1_instructor_participation

        cls.course1_student_participation = Participation.objects.filter(
            course=cls.course1,
            roles__identifier="student",
            status=participation_status.active
        ).first()
        assert cls.course1_student_participation

        cls.course1_ta_participation = Participation.objects.filter(
            course=cls.course1,
            roles__identifier="ta",
            status=participation_status.active
        ).first()
        assert cls.course1_ta_participation
        cls.course1_page_url = cls.get_course_page_url(cls.course1.identifier)

        cls.course2 = cls.course_qset.last()
        cls.course2_instructor_participation = Participation.objects.filter(
            course=cls.course2,
            roles__identifier="instructor",
            status=participation_status.active
        ).first()
        assert cls.course2_instructor_participation

        cls.course2_student_participation = Participation.objects.filter(
            course=cls.course2,
            roles__identifier="student",
            status=participation_status.active
        ).first()
        assert cls.course2_student_participation

        cls.course2_ta_participation = Participation.objects.filter(
            course=cls.course2,
            roles__identifier="ta",
            status=participation_status.active
        ).first()
        assert cls.course2_ta_participation
        cls.course2_page_url = cls.get_course_page_url(cls.course2.identifier)

        cls.c.logout()

    def setUp(self):  # noqa
        super(TwoCourseTestMixin, self).setUp()
        # reload objects created during setUpTestData in case they were modified in
        # tests. Ref: https://goo.gl/AuzJRC#django.test.TestCase.setUpTestData
        self.course1.refresh_from_db()
        self.course1_instructor_participation.refresh_from_db()
        self.course1_student_participation.refresh_from_db()
        self.course1_ta_participation.refresh_from_db()

        self.course2.refresh_from_db()
        self.course2_instructor_participation.refresh_from_db()
        self.course2_student_participation.refresh_from_db()
        self.course2_ta_participation.refresh_from_db()


class SingleCoursePageTestMixin(SingleCourseTestMixin):
    # This serves as cache
    _default_session_id = None

    flow_id = QUIZ_FLOW_ID

    @classmethod
    def update_default_flow_session_id(cls, course_identifier):
        cls._default_session_id = cls.default_flow_params["flow_session_id"]

    @classmethod
    def get_default_flow_session_id(cls, course_identifier):
        if cls._default_session_id is not None:
            return cls._default_session_id
        cls._default_session_id = cls.get_latest_session_id(course_identifier)
        return cls._default_session_id


class TwoCoursePageTestMixin(TwoCourseTestMixin):
    _course1_default_session_id = None
    _course2_default_session_id = None

    @property
    def flow_id(self):
        raise NotImplementedError

    @classmethod
    def get_default_flow_session_id(cls, course_identifier):
        if course_identifier == cls.course1.identifier:
            if cls._course1_default_session_id is not None:
                return cls._course1_default_session_id
            cls._course1_default_session_id = (
                cls.get_last_session_id(course_identifier))
            return cls._course1_default_session_id
        if course_identifier == cls.course2.identifier:
            if cls._course2_default_session_id is not None:
                return cls._course2_default_session_id
            cls._course2_default_session_id = (
                cls.get_last_session_id(course_identifier))
            return cls._course2_default_session_id

    @classmethod
    def update_default_flow_session_id(cls, course_identifier):
        new_session_id = cls.default_flow_params["flow_session_id"]
        if course_identifier == cls.course1.identifier:
            cls._course1_default_session_id = new_session_id
        elif course_identifier == cls.course2.identifier:
            cls._course2_default_session_id = new_session_id


class SingleCourseQuizPageTestMixin(SingleCoursePageTestMixin):

    skip_code_question = True

    @classmethod
    def ensure_grading_ui_get(cls, page_id):
        with cls.temporarily_switch_to_user(cls.instructor_participation.user):
            url = cls.get_page_grading_url_by_page_id(page_id)
            resp = cls.c.get(url)
            assert resp.status_code == 200

    @classmethod
    def ensure_analytic_page_get(cls, group_id, page_id):
        with cls.temporarily_switch_to_user(cls.instructor_participation.user):
            resp = cls.get_flow_page_analytics(
                flow_id=cls.flow_id, group_id=group_id,
                page_id=page_id)
            assert resp.status_code == 200

    @classmethod
    def ensure_download_submission(
            cls, group_id, page_id, dl_file_extension=None,
            file_with_ext_count=None):
        with cls.temporarily_switch_to_user(cls.instructor_participation.user):
            group_page_id = "%s/%s" % (group_id, page_id)
            resp = cls.post_download_all_submissions_by_group_page_id(
                group_page_id=group_page_id, flow_id=cls.flow_id)
            assert resp.status_code == 200
            prefix, zip_file = resp["Content-Disposition"].split('=')
            assert prefix == "attachment; filename"
            assert resp.get('Content-Type') == "application/zip"
            if dl_file_extension:
                buf = six.BytesIO(resp.content)
                import zipfile
                with zipfile.ZipFile(buf, 'r') as zf:
                    assert zf.testzip() is None
                    # todo: make more assertions in terms of file content

                    for f in zf.filelist:
                        assert f.file_size > 0

                    if file_with_ext_count is None:
                        assert len([f for f in zf.filelist if
                                 f.filename.endswith(dl_file_extension)]) > 0
                    else:
                        assert (
                                len([f for f in zf.filelist if
                                     f.filename.endswith(dl_file_extension)])
                                == file_with_ext_count)

    @classmethod