Added a new LTI-based course tab, and LtiDiscussion tab

This PR lays the groundwork for a an LTI tab that can embed any LTI1.1-based
tool as an course tab. It also adds another tab based on this LTI Tab that
offers special support for embedding LTI-based discussion tools in a course
tab. If enabled this will replace the existing discussion tab.

openedx/features/lti_course_tab/tests.py

@@ -0,0 +1,39 @@
+"""
+Tests for LTI Course tabs.
+"""
+from unittest.mock import Mock, patch
+
+from lms.djangoapps.courseware.tests.test_tabs import TabTestCase
+from openedx.features.lti_course_tab.tab import DiscussionLtiCourseTab
+
+
+class DiscussionLtiCourseTabTestCase(TabTestCase):
+    """Test cases for LTI Discussion Tab."""
+
+    def check_discussion_tab(self):
+        """Helper function for verifying the LTI discussion tab."""
+        return self.check_tab(
+            tab_class=DiscussionLtiCourseTab,
+            dict_tab={'type': DiscussionLtiCourseTab.type, 'name': 'same'},
+            expected_link=self.reverse('course_tab_view', args=[str(self.course.id), DiscussionLtiCourseTab.type]),
+            expected_tab_id=DiscussionLtiCourseTab.type,
+            invalid_dict_tab=None,
+        )
+
+    @patch('openedx.features.lti_course_tab.tab.DiscussionsConfiguration.get')
+    @patch('common.djangoapps.student.models.CourseEnrollment.is_enrolled')
+    def test_discussion_lti_tab(self, is_enrolled, discussion_config_get):
+        is_enrolled.return_value = True
+        mock_config = Mock()
+        mock_config.lti_configuration = {}
+        mock_config.enabled = False
+        discussion_config_get.return_value = mock_config
+        tab = self.check_discussion_tab()
+        self.check_can_display_results(
+            tab, for_staff_only=True, for_enrolled_users_only=True, expected_value=False
+        )
+        mock_config.enabled = True
+        self.check_discussion_tab()
+        self.check_can_display_results(
+            tab, for_staff_only=True, for_enrolled_users_only=True
+        )