OLX export: Reverted url_name from a constant to course run

- New exported courses include course run information in:
  - `url_name` of root course node
  - file name of root node in course folder
  - root key name in policy.json
  - directory name inside policies folder

- when imported via management command, the OLX will overwrite an
available existing course with the same course key (i.e. same org,
course number and course run)
  - if there is no matching course, one will be created

- when imported via the studio web ui (or import API), the OLX will
replace the current course (no change in behavior)

- courses exported with this commit have been tested to import via
management command and studio web UI in hawthorn and ginkgo releases.
They should also work in prior releases, but have not been tested.

common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py

@@ -188,7 +188,7 @@ class CrossStoreXMLRoundtrip(CourseComparisonTest, PartitionTestCase):
                         self.assertEqual(source_course.url_name, 'course')
 
                         export_dir_path = path(self.export_dir)
-                        policy_dir = export_dir_path / 'exported_source_course' / 'policies' / source_course.url_name
+                        policy_dir = export_dir_path / 'exported_source_course' / 'policies' / source_course_key.run
                         policy_path = policy_dir / 'policy.json'
                         self.assertTrue(os.path.exists(policy_path))
 

common/lib/xmodule/xmodule/modulestore/xml_exporter.py

@@ -166,6 +166,7 @@ class ExportManager(object):
                 # change all of the references inside the course to use the xml expected key type w/o version & branch
                 xml_centric_courselike_key = self.get_key()
                 adapt_references(courselike, xml_centric_courselike_key, export_fs)
+                root.set('url_name', self.courselike_key.run)
                 courselike.add_xml_to_node(root)
 
             # Make any needed adjustments to the root node.
@@ -267,10 +268,6 @@ class CourseExportManager(ExportManager):
         )
 
         course_policy_dir_name = courselike.location.run
-        if courselike.url_name != courselike.location.run and courselike.url_name == 'course':
-            # Use url_name for split mongo because course_run is not used when loading policies.
-            course_policy_dir_name = courselike.url_name
-
         course_run_policy_dir = policies_dir.makedir(course_policy_dir_name, recreate=True)
 
         # export the grading policy
@@ -280,7 +277,7 @@ class CourseExportManager(ExportManager):
 
         # export all of the course metadata in policy.json
         with course_run_policy_dir.open(u'policy.json', 'wb') as course_policy:
-            policy = {'course/' + courselike.location.block_id: own_metadata(courselike)}
+            policy = {'course/' + courselike.location.run: own_metadata(courselike)}
             course_policy.write(dumps(policy, cls=EdxJSONEncoder, sort_keys=True, indent=4).encode('utf-8'))
 
         _export_drafts(self.modulestore, self.courselike_key, export_fs, xml_centric_courselike_key)

common/lib/xmodule/xmodule/tests/test_import.py

@@ -32,6 +32,7 @@ from xblock.runtime import KvsFieldData, DictKeyValueStore
 
 ORG = 'test_org'
 COURSE = 'test_course'
+RUN = 'test_run'
 
 
 class DummySystem(ImportSystem):
@@ -43,7 +44,7 @@ class DummySystem(ImportSystem):
             xmlstore = LibraryXMLModuleStore("data_dir", source_dirs=[], load_error_modules=load_error_modules)
         else:
             xmlstore = XMLModuleStore("data_dir", source_dirs=[], load_error_modules=load_error_modules)
-        course_id = CourseKey.from_string('/'.join([ORG, COURSE, 'test_run']))
+        course_id = CourseKey.from_string('/'.join([ORG, COURSE, RUN]))
         course_dir = "test_dir"
         error_tracker = Mock()
 
@@ -197,7 +198,7 @@ class ImportTestCase(BaseCourseTestCase):
         # Now make sure the exported xml is a sequential
         self.assertEqual(node.tag, 'sequential')
 
-    def course_descriptor_inheritance_check(self, descriptor, from_date_string, unicorn_color, url_name):
+    def course_descriptor_inheritance_check(self, descriptor, from_date_string, unicorn_color, course_run=RUN):
         """
         Checks to make sure that metadata inheritance on a course descriptor is respected.
         """
@@ -228,7 +229,7 @@ class ImportTestCase(BaseCourseTestCase):
         self.assertEqual(node.attrib['org'], ORG)
 
         # Does the course still have unicorns?
-        with descriptor.runtime.export_fs.open(u'course/{url_name}.xml'.format(url_name=url_name)) as f:
+        with descriptor.runtime.export_fs.open(u'course/{course_run}.xml'.format(course_run=course_run)) as f:
             course_xml = etree.fromstring(f.read())
 
         self.assertEqual(course_xml.attrib['unicorn'], unicorn_color)
@@ -267,7 +268,7 @@ class ImportTestCase(BaseCourseTestCase):
         )
         descriptor = system.process_xml(start_xml)
         compute_inherited_metadata(descriptor)
-        self.course_descriptor_inheritance_check(descriptor, from_date_string, unicorn_color, url_name)
+        self.course_descriptor_inheritance_check(descriptor, from_date_string, unicorn_color)
 
     def test_library_metadata_import_export(self):
         """Two checks:
@@ -300,7 +301,7 @@ class ImportTestCase(BaseCourseTestCase):
         compute_inherited_metadata(descriptor)
         # Check the course module, since it has inheritance
         descriptor = descriptor.get_children()[0]
-        self.course_descriptor_inheritance_check(descriptor, from_date_string, unicorn_color, url_name)
+        self.course_descriptor_inheritance_check(descriptor, from_date_string, unicorn_color)
 
     def test_metadata_no_inheritance(self):
         """

common/lib/xmodule/xmodule/x_module.py

@@ -1116,7 +1116,11 @@ class XModuleDescriptor(HTMLSnippet, ResourceTemplates, XModuleMixin):
         node.tag = exported_node.tag
         node.text = exported_node.text
         node.tail = exported_node.tail
+
         for key, value in exported_node.items():
+            if key == 'url_name' and value == 'course' and key in node.attrib:
+                # if url_name is set in ExportManager then do not override it here.
+                continue
             node.set(key, value)
 
         node.extend(list(exported_node))

common/lib/xmodule/xmodule/xml_module.py

@@ -487,7 +487,11 @@ class XmlParserMixin(object):
         if self.export_to_file():
             # Write the definition to a file
             url_path = name_to_pathname(self.url_name)
-            filepath = self._format_filepath(self.category, url_path)
+            # if folder is course then create file with name {course_run}.xml
+            filepath = self._format_filepath(
+                self.category,
+                self.location.run if self.category == 'course' else url_path,
+            )
             self.runtime.export_fs.makedirs(os.path.dirname(filepath), recreate=True)
             with self.runtime.export_fs.open(filepath, 'wb') as fileobj:
                 ElementTree(xml_object).write(fileobj, pretty_print=True, encoding='utf-8')