Have DiscussionXBlock take care of loading JS and CSS files it depends on.

* Add openedx.core.lib.xblock_builtin.get_css_dependencies and get_js_dependencies,
  which respect PIPELINE_ENABLED setting when determining dependencies.
* Move new discussion-related Sass files into discussion subdirectory.
* Use "load_unicode" instead of "render_template" to load JS to add to fragment for DiscussionXBlock.
* Remove unused "course" parameter from context for DiscussionXBlock.student_view.
* Add RTL stylesheet for DiscussionXBlock, and enable the block to load correct stylesheet.
* Load MathJax only once, and include code for configuring MathJax in discussion bundle.
* Make sure username renders correctly in DiscussionXBlock response header.
* Move WYSIWYIG Markdown editor styles to _build-discussion.scss.
* Remove unnecessary import of discussion/utilities/v1-compatibility from _build-discussion.scss.
* Keep courseware-chromeless.html in sync with courseware.html.
* Load CSS for discussions on Teams tab.  This makes it possible to remove CSS for discussions from Sass files for "Course" tab.
* Load js/src/tooltip_manager.js, jquery.autocomplete.js and jquery.autocomplete.css on "Course" tab.

openedx/core/lib/tests/test_xblock_utils.py

@@ -22,7 +22,11 @@ from openedx.core.lib.xblock_utils import (
     replace_jump_to_id_urls,
     replace_course_urls,
     replace_static_urls,
-    sanitize_html_id
+    sanitize_html_id,
+)
+from openedx.core.lib.xblock_builtin import (
+    get_css_dependencies,
+    get_js_dependencies,
 )
 
 
@@ -181,3 +185,41 @@ class TestXblockUtils(SharedModuleStoreTestCase):
         clean_string = sanitize_html_id(dirty_string)
 
         self.assertEqual(clean_string, 'I_have_un_allowed_characters')
+
+    @ddt.data(
+        (True, ["combined.css"]),
+        (False, ["a.css", "b.css", "c.css"]),
+    )
+    @ddt.unpack
+    def test_get_css_dependencies(self, pipeline_enabled, expected_css_dependencies):
+        """
+        Verify that `get_css_dependencies` returns correct list of files.
+        """
+        pipeline_css = {
+            'style-group': {
+                'source_filenames': ["a.css", "b.css", "c.css"],
+                'output_filename': "combined.css"
+            }
+        }
+        with self.settings(PIPELINE_ENABLED=pipeline_enabled, PIPELINE_CSS=pipeline_css):
+            css_dependencies = get_css_dependencies("style-group")
+            self.assertEqual(css_dependencies, expected_css_dependencies)
+
+    @ddt.data(
+        (True, ["combined.js"]),
+        (False, ["a.js", "b.js", "c.js"]),
+    )
+    @ddt.unpack
+    def test_get_js_dependencies(self, pipeline_enabled, expected_js_dependencies):
+        """
+        Verify that `get_js_dependencies` returns correct list of files.
+        """
+        pipeline_js = {
+            'js-group': {
+                'source_filenames': ["a.js", "b.js", "c.js"],
+                'output_filename': "combined.js"
+            }
+        }
+        with self.settings(PIPELINE_ENABLED=pipeline_enabled, PIPELINE_JS=pipeline_js):
+            js_dependencies = get_js_dependencies("js-group")
+            self.assertEqual(js_dependencies, expected_js_dependencies)

openedx/core/lib/xblock_builtin/__init__.py

@@ -0,0 +1,31 @@
+"""
+Helper functions shared by built-in XBlocks.
+
+"""
+
+
+from django.conf import settings
+
+
+def get_css_dependencies(group):
+    """
+    Returns list of CSS dependencies belonging to `group` in settings.PIPELINE_JS.
+
+    Respects `PIPELINE_ENABLED` setting.
+    """
+    if settings.PIPELINE_ENABLED:
+        return [settings.PIPELINE_CSS[group]['output_filename']]
+    else:
+        return settings.PIPELINE_CSS[group]['source_filenames']
+
+
+def get_js_dependencies(group):
+    """
+    Returns list of JS dependencies belonging to `group` in settings.PIPELINE_JS.
+
+    Respects `PIPELINE_ENABLED` setting.
+    """
+    if settings.PIPELINE_ENABLED:
+        return [settings.PIPELINE_JS[group]['output_filename']]
+    else:
+        return settings.PIPELINE_JS[group]['source_filenames']

openedx/core/lib/xblock_builtin/xblock_discussion/xblock_discussion.py

@@ -4,6 +4,9 @@ Discussion XBlock
 """
 import logging
 
+from django.templatetags.static import static
+from django.utils.translation import get_language_bidi
+
 from xblockutils.resources import ResourceLoader
 from xblockutils.studio_editable import StudioEditableXBlockMixin
 from xmodule.raw_module import RawDescriptor
@@ -13,6 +16,9 @@ from xblock.fields import Scope, String, UNIQUE_ID
 from xblock.fragment import Fragment
 from xmodule.xml_module import XmlParserMixin
 
+from openedx.core.lib.xblock_builtin import get_css_dependencies, get_js_dependencies
+
+
 log = logging.getLogger(__name__)
 loader = ResourceLoader(__name__)  # pylint: disable=invalid-name
 
@@ -88,6 +94,57 @@ class DiscussionXBlock(XBlock, StudioEditableXBlockMixin, XmlParserMixin):
             return None
         return user_service._django_user  # pylint: disable=protected-access
 
+    @staticmethod
+    def vendor_js_dependencies():
+        """
+        Returns list of vendor JS files that this XBlock depends on.
+
+        The helper function that it uses to obtain the list of vendor JS files
+        works in conjunction with the Django pipeline to ensure that in development mode
+        the files are loaded individually, but in production just the single bundle is loaded.
+        """
+        return get_js_dependencies('discussion_vendor')
+
+    @staticmethod
+    def js_dependencies():
+        """
+        Returns list of JS files that this XBlock depends on.
+
+        The helper function that it uses to obtain the list of JS files
+        works in conjunction with the Django pipeline to ensure that in development mode
+        the files are loaded individually, but in production just the single bundle is loaded.
+        """
+        return get_js_dependencies('discussion')
+
+    @staticmethod
+    def css_dependencies():
+        """
+        Returns list of CSS files that this XBlock depends on.
+
+        The helper function that it uses to obtain the list of CSS files
+        works in conjunction with the Django pipeline to ensure that in development mode
+        the files are loaded individually, but in production just the single bundle is loaded.
+        """
+        if get_language_bidi():
+            return get_css_dependencies('style-inline-discussion-rtl')
+        else:
+            return get_css_dependencies('style-inline-discussion')
+
+    def add_resource_urls(self, fragment):
+        """
+        Adds URLs for JS and CSS resources that this XBlock depends on to `fragment`.
+        """
+        # Head dependencies
+        for vendor_js_file in self.vendor_js_dependencies():
+            fragment.add_resource_url(static(vendor_js_file), "application/javascript", "head")
+
+        for css_file in self.css_dependencies():
+            fragment.add_css_url(static(css_file))
+
+        # Body dependencies
+        for js_file in self.js_dependencies():
+            fragment.add_javascript_url(static(js_file))
+
     def has_permission(self, permission):
         """
         Encapsulates lms specific functionality, as `has_permission` is not
@@ -108,12 +165,11 @@ class DiscussionXBlock(XBlock, StudioEditableXBlockMixin, XmlParserMixin):
         """
         fragment = Fragment()
 
-        course = self.runtime.modulestore.get_course(self.course_key)
+        self.add_resource_urls(fragment)
 
         context = {
             'discussion_id': self.discussion_id,
             'user': self.django_user,
-            'course': course,
             'course_id': self.course_key,
             'can_create_thread': self.has_permission("create_thread"),
             'can_create_comment': self.has_permission("create_comment"),