feat: add reset option to the Randomized Content Block

common/lib/xmodule/xmodule/assets/library_content/public/js/library_content_reset.js

@@ -0,0 +1,18 @@
+/* JavaScript for reset option that can be done on a randomized LibraryContentBlock */
+function LibraryContentReset(runtime, element) {
+  $('.problem-reset-btn', element).click((e) => {
+    e.preventDefault();
+    $.post({
+      url: runtime.handlerUrl(element, 'reset_selected_children'),
+      success(data) {
+        edx.HtmlUtils.setHtml(element, edx.HtmlUtils.HTML(data));
+        // Rebind the reset button for the block
+        XBlock.initializeBlock(element);
+        // Render the new set of problems (XBlocks)
+        $(".xblock", element).each(function(i, child) {
+          XBlock.initializeBlock(child);
+        });
+      },
+    });
+  });
+}

common/lib/xmodule/xmodule/library_content_module.py

@@ -8,6 +8,7 @@
 import random
 from copy import copy
 from gettext import ngettext
+from rest_framework import status
 
 import bleach
 from django.conf import settings
@@ -21,7 +22,7 @@
 from webob import Response
 from xblock.completable import XBlockCompletionMode
 from xblock.core import XBlock
-from xblock.fields import Integer, List, Scope, String
+from xblock.fields import Integer, List, Scope, String, Boolean
 
 from capa.responsetypes import registry
 from xmodule.mako_module import MakoTemplateBlockBase
@@ -176,6 +177,14 @@ def completion_mode(cls):  # pylint: disable=no-self-argument
         default=[],
         scope=Scope.user_state,
     )
+    # This cannot be called `show_reset_button`, because children blocks inherit this as a default value.
+    allow_resetting_children = Boolean(
+        display_name=_("Show Reset Button"),
+        help=_("Determines whether a 'Reset Problems' button is shown, so users may reset their answers and reshuffle "
+               "selected items."),
+        scope=Scope.settings,
+        default=False
+    )
 
     @property
     def source_library_key(self):
@@ -346,6 +355,27 @@ def selected_children(self):
 
         return self.selected
 
+    @XBlock.handler
+    def reset_selected_children(self, _, __):
+        """
+        Resets the XBlock's state for a user.
+
+        This resets the state of all `selected` children and then clears the `selected` field
+        so that the new blocks are randomly chosen for this user.
+        """
+        if not self.allow_resetting_children:
+            return Response('"Resetting selected children" is not allowed for this XBlock',
+                            status=status.HTTP_400_BAD_REQUEST)
+
+        for block_type, block_id in self.selected_children():
+            block = self.runtime.get_block(self.location.course_key.make_usage_key(block_type, block_id))
+            if hasattr(block, 'reset_problem'):
+                block.reset_problem(None)
+                block.save()
+
+        self.selected = []
+        return Response(json.dumps(self.student_view({}).content))
+
     def _get_selected_child_blocks(self):
         """
         Generator returning XBlock instances of the children selected for the
@@ -383,7 +413,11 @@ def student_view(self, context):  # lint-amnesty, pylint: disable=missing-functi
             'show_bookmark_button': False,
             'watched_completable_blocks': set(),
             'completion_delay_ms': None,
+            'reset_button': self.allow_resetting_children,
         }))
+
+        fragment.add_javascript_url(self.runtime.local_resource_url(self, 'public/js/library_content_reset.js'))
+        fragment.initialize_js('LibraryContentReset')
         return fragment
 
     def author_view(self, context):

common/lib/xmodule/xmodule/tests/test_library_content.py

@@ -3,14 +3,16 @@
 
 Higher-level tests are in `cms/djangoapps/contentstore/tests/test_libraries.py`.
 """
-from unittest.mock import Mock, patch
+import ddt
+from unittest.mock import MagicMock, Mock, patch
 
 from bson.objectid import ObjectId
 from fs.memoryfs import MemoryFS
 from lxml import etree
 from search.search_engine_base import SearchEngine
 from web_fragments.fragment import Fragment
 from xblock.runtime import Runtime as VanillaRuntime
+from rest_framework import status
 
 from xmodule.library_content_module import ANY_CAPA_TYPE_VALUE, LibraryContentBlock
 from xmodule.library_tools import LibraryToolsService
@@ -20,6 +22,7 @@
 from xmodule.tests import get_test_system
 from xmodule.validation import StudioValidationMessage
 from xmodule.x_module import AUTHOR_VIEW
+from xmodule.capa_module import ProblemBlock
 
 from .test_course_module import DummySystem as TestImportSystem
 
@@ -30,6 +33,7 @@ class LibraryContentTest(MixedSplitTestCase):
     """
     Base class for tests of LibraryContentBlock (library_content_block.py)
     """
+
     def setUp(self):
         super().setUp()
 
@@ -164,6 +168,7 @@ def test_xml_import_with_comments(self):
         self._verify_xblock_properties(imported_lc_block)
 
 
+@ddt.ddt
 class LibraryContentBlockTestMixin:
     """
     Basic unit tests for LibraryContentBlock
@@ -378,6 +383,45 @@ def _change_count_and_refresh_children(self, count):
         assert len(selected) == count
         return selected
 
+    @ddt.data(
+        # User resets selected children with reset button on content block
+        (True, 8),
+        # User resets selected children without reset button on content block
+        (False, 8),
+    )
+    @ddt.unpack
+    def test_reset_selected_children_capa_blocks(self, allow_resetting_children, max_count):
+        """
+        Tests that the `reset_selected_children` method of a content block resets only
+        XBlocks that have a `reset_problem` attribute when `allow_resetting_children` is True
+
+        This test block has 4 HTML XBlocks and 4 Problem XBlocks. Therefore, if we ensure
+        that the `reset_problem` has been called len(self.problem_types) times, then
+        it means that this is working correctly
+        """
+        self.lc_block.allow_resetting_children = allow_resetting_children
+        self.lc_block.max_count = max_count
+        # Add some capa blocks
+        self._create_capa_problems()
+        self.lc_block.refresh_children()
+        self.lc_block = self.store.get_item(self.lc_block.location)
+        # Mock the student view to return an empty dict to be returned as response
+        self.lc_block.student_view = MagicMock()
+        self.lc_block.student_view.return_value.content = {}
+
+        with patch.object(ProblemBlock, 'reset_problem', return_value={'success': True}) as reset_problem:
+            response = self.lc_block.reset_selected_children(None, None)
+
+        if allow_resetting_children:
+            self.lc_block.student_view.assert_called_once_with({})
+            assert reset_problem.call_count == len(self.problem_types)
+            assert response.status_code == status.HTTP_200_OK
+            assert response.content_type == "text/html"
+            assert response.body == b"{}"
+        else:
+            reset_problem.assert_not_called()
+            assert response.status_code == status.HTTP_400_BAD_REQUEST
+
 
 @patch('xmodule.library_tools.SearchEngine.get_search_engine', Mock(return_value=None, autospec=True))
 class TestLibraryContentBlockNoSearchIndex(LibraryContentBlockTestMixin, LibraryContentTest):
@@ -396,6 +440,7 @@ class TestLibraryContentBlockWithSearchIndex(LibraryContentBlockTestMixin, Libra
     """
     Tests for library container with mocked search engine response.
     """
+
     def _get_search_response(self, field_dictionary=None):
         """ Mocks search response as returned by search engine """
         target_type = field_dictionary.get('problem_types')

lms/static/sass/course/courseware/_courseware.scss

@@ -635,6 +635,17 @@ html.video-fullscreen {
         border-bottom: 1px solid #ddd;
         margin-bottom: ($baseline*0.75);
         padding: 0 0 15px;
+
+        .problem-reset-btn-wrapper {
+          position: relative;
+          .problem-reset-btn {
+            &:hover,
+            &:focus,
+            &:active {
+              color: $primary;
+            }
+          }
+        }
       }
 
       .vert > .xblock-student_view.is-hidden,

lms/templates/vert_module.html

@@ -69,6 +69,12 @@ <h2 class="hd hd-2 unit-title">${unit_title}</h2>
 % endfor
 </div>
 
+% if reset_button:
+  <div class="problem-reset-btn-wrapper">
+    <button type="button" class="problem-reset-btn btn-link" data-value="${_('Reset Problems')}"><span aria-hidden="true">${_('Reset Problems')}</span><span class="sr">${_("Reset Problems")}</span></button>
+  </div>
+% endif
+
 <%static:require_module_async module_name="js/dateutil_factory" class_name="DateUtilFactory">
     DateUtilFactory.transform('.localized-datetime');
 </%static:require_module_async>