From 0b1c7db96708379953cba056b25297ccc173f2b2 Mon Sep 17 00:00:00 2001
From: DawoudSheraz <dawoud.sheraz@gmail.com>
Date: Tue, 28 Jan 2020 12:03:13 +0500
Subject: [PATCH] add multiple correct values check for Dropdown problems

---
 common/lib/capa/capa/capa_problem.py          | 19 ++++++++-
 .../lib/capa/capa/tests/test_capa_problem.py  | 32 ++++++++++++++
 common/lib/xmodule/xmodule/capa_module.py     | 28 ++++++++-----
 .../xmodule/xmodule/tests/test_capa_module.py | 21 ++++++++++
 .../courseware/tests/test_module_render.py    | 42 +++++++++++++++++++
 .../grades/tests/test_transformer.py          | 29 +++++++++++++
 6 files changed, 159 insertions(+), 12 deletions(-)

diff --git a/common/lib/capa/capa/capa_problem.py b/common/lib/capa/capa/capa_problem.py
index 5f44750ccb..1571ad54b8 100644
--- a/common/lib/capa/capa/capa_problem.py
+++ b/common/lib/capa/capa/capa_problem.py
@@ -245,6 +245,22 @@ class LoncapaProblem(object):
         This translation takes in the new format and synthesizes the old option= attribute
         so all downstream logic works unchanged with the new <option> tag format.
         """
+        def is_optioninput_valid(optioninput):
+            """
+            Verifies if a given optioninput xml is valid or not.
+
+            A given optioninput(Dropdown) problem is invalid if it has more than one correct answer.
+
+            Argument:
+                optioninput: dropdown specification tree
+            Returns:
+                boolean: signifying if the optioninput is valid or not.
+            """
+            correct_options = [
+                option.get('correct').upper() == 'TRUE' for option in optioninput.findall('./option')
+            ]
+            return correct_options.count(True) in (0, 1)
+
         additionals = tree.xpath('//stringresponse/additional_answer')
         for additional in additionals:
             answer = additional.get('answer')
@@ -252,8 +268,9 @@ class LoncapaProblem(object):
             if not answer and text:  # trigger of old->new conversion
                 additional.set('answer', text)
                 additional.text = ''
-
         for optioninput in tree.xpath('//optioninput'):
+            if not is_optioninput_valid(optioninput):
+                raise responsetypes.LoncapaProblemError("Dropdown questions can only have one correct answer.")
             correct_option = None
             child_options = []
             for option_element in optioninput.findall('./option'):
diff --git a/common/lib/capa/capa/tests/test_capa_problem.py b/common/lib/capa/capa/tests/test_capa_problem.py
index 6c59985d32..f3f06c3936 100644
--- a/common/lib/capa/capa/tests/test_capa_problem.py
+++ b/common/lib/capa/capa/tests/test_capa_problem.py
@@ -12,6 +12,7 @@ from lxml import etree
 from markupsafe import Markup
 from mock import patch
 
+from capa.responsetypes import LoncapaProblemError
 from capa.tests.helpers import new_loncapa_problem
 from openedx.core.djangolib.markup import HTML
 
@@ -460,6 +461,37 @@ class CAPAProblemTest(unittest.TestCase):
         self.assert_question_tag(question1, question2, tag='label', label_attr=False)
         self.assert_question_tag(question1, question2, tag='p', label_attr=True)
 
+    def test_optionresponse_xml_compatibility(self):
+        """
+        Verify that an optionresponse problem with multiple correct answers is not instantiated.
+
+        Scenario:
+        Given an optionresponse/Dropdown problem
+        If there are multiple correct answers
+        Then the problem is not instantiated
+        And Loncapa problem error exception is raised
+        If the problem is corrected by including only one correct answer
+        Then the problem is created successfully
+        """
+        xml = """
+        <problem>
+            <optionresponse>
+              <p>You can use this template as a guide to the simple editor markdown and OLX markup to use for dropdown problems. Edit this component to replace this template with your own assessment.</p>
+            <label>Add the question text, or prompt, here. This text is required.</label>
+            <description>You can add an optional tip or note related to the prompt like this. </description>
+            <optioninput>
+                <option correct="False">an incorrect answer</option>
+                <option correct="True">the correct answer</option>
+                <option correct="{correctness}">an incorrect answer</option>
+              </optioninput>
+            </optionresponse>
+        </problem>
+        """
+        with self.assertRaises(LoncapaProblemError):
+            new_loncapa_problem(xml.format(correctness=True))
+        problem = new_loncapa_problem(xml.format(correctness=False))
+        self.assertIsNotNone(problem)
+
 
 @ddt.ddt
 class CAPAMultiInputProblemTest(unittest.TestCase):
diff --git a/common/lib/xmodule/xmodule/capa_module.py b/common/lib/xmodule/xmodule/capa_module.py
index 6a28595c61..3677b75669 100644
--- a/common/lib/xmodule/xmodule/capa_module.py
+++ b/common/lib/xmodule/xmodule/capa_module.py
@@ -344,7 +344,7 @@ class ProblemBlock(
 
     def max_score(self):
         """
-        Return the problem's max score
+        Return the problem's max score if problem is instantiated successfully, else return max score of 0.
         """
         from capa.capa_problem import LoncapaProblem, LoncapaSystem
         capa_system = LoncapaSystem(
@@ -363,16 +363,22 @@ class ProblemBlock(
             xqueue=None,
             matlab_api_key=None,
         )
-        lcp = LoncapaProblem(
-            problem_text=self.data,
-            id=self.location.html_id(),
-            capa_system=capa_system,
-            capa_module=self,
-            state={},
-            seed=1,
-            minimal_init=True,
-        )
-        return lcp.get_max_score()
+        try:
+            lcp = LoncapaProblem(
+                problem_text=self.data,
+                id=self.location.html_id(),
+                capa_system=capa_system,
+                capa_module=self,
+                state={},
+                seed=1,
+                minimal_init=True,
+            )
+        except responsetypes.LoncapaProblemError:
+            log.exception(u"LcpFatalError for block {} while getting max score".format(str(self.location)))
+            maximum_score = 0
+        else:
+            maximum_score = lcp.get_max_score()
+        return maximum_score
 
     def generate_report_data(self, user_state_iterator, limit_responses=None):
         """
diff --git a/common/lib/xmodule/xmodule/tests/test_capa_module.py b/common/lib/xmodule/xmodule/tests/test_capa_module.py
index cf77564804..9e48967ca0 100644
--- a/common/lib/xmodule/xmodule/tests/test_capa_module.py
+++ b/common/lib/xmodule/xmodule/tests/test_capa_module.py
@@ -2871,6 +2871,27 @@ class ProblemBlockXMLTest(unittest.TestCase):
         with self.assertRaises(etree.XMLSyntaxError):
             self._create_descriptor(sample_invalid_xml, name="Invalid XML")
 
+    def test_invalid_dropdown_xml(self):
+        """
+        Verify the capa problem cannot be created from dropdown xml with multiple correct answers.
+        """
+        problem_xml = textwrap.dedent("""
+        <problem>
+            <optionresponse>
+              <p>You can use this template as a guide to the simple editor markdown and OLX markup to use for dropdown problems. Edit this component to replace this template with your own assessment.</p>
+            <label>Add the question text, or prompt, here. This text is required.</label>
+            <description>You can add an optional tip or note related to the prompt like this. </description>
+            <optioninput>
+                <option correct="False">an incorrect answer</option>
+                <option correct="True">the correct answer</option>
+                <option correct="True">an incorrect answer</option>
+              </optioninput>
+            </optionresponse>
+        </problem>
+        """)
+        with self.assertRaises(Exception):
+            CapaFactory.create(xml=problem_xml)
+
 
 class ComplexEncoderTest(unittest.TestCase):
 
diff --git a/lms/djangoapps/courseware/tests/test_module_render.py b/lms/djangoapps/courseware/tests/test_module_render.py
index 488bac662e..efb3341390 100644
--- a/lms/djangoapps/courseware/tests/test_module_render.py
+++ b/lms/djangoapps/courseware/tests/test_module_render.py
@@ -6,6 +6,7 @@ Test for lms courseware app, module render unit
 
 import itertools
 import json
+import textwrap
 from datetime import datetime
 from functools import partial
 
@@ -1880,6 +1881,47 @@ class TestStaffDebugInfo(SharedModuleStoreTestCase):
         result_fragment = module.render(STUDENT_VIEW)
         self.assertIn('Staff Debug', result_fragment.content)
 
+    def test_staff_debug_info_score_for_invalid_dropdown(self):
+        """
+        Verifies that for an invalid drop down problem, the max score is set
+        to zero in the html.
+        """
+        problem_xml = """
+        <problem>
+            <optionresponse>
+              <p>You can use this template as a guide to the simple editor markdown and OLX markup to use for dropdown problems. Edit this component to replace this template with your own assessment.</p>
+            <label>Add the question text, or prompt, here. This text is required.</label>
+            <description>You can add an optional tip or note related to the prompt like this. </description>
+            <optioninput>
+                <option correct="False">an incorrect answer</option>
+                <option correct="True">the correct answer</option>
+                <option correct="True">an incorrect answer</option>
+              </optioninput>
+            </optionresponse>
+        </problem>
+        """
+        problem_descriptor = ItemFactory.create(
+            category='problem',
+            data=problem_xml
+        )
+        module = render.get_module(
+            self.user,
+            self.request,
+            problem_descriptor.location,
+            self.field_data_cache
+        )
+        html_fragment = module.render(STUDENT_VIEW)
+        expected_score_override_html = textwrap.dedent("""<div>
+        <label for="sd_fs_{block_id}">Score (for override only):</label>
+        <input type="text" tabindex="0" id="sd_fs_{block_id}" placeholder="0"/>
+        <label for="sd_fs_{block_id}"> / 0</label>
+      </div>""")
+
+        self.assertIn(
+            expected_score_override_html.format(block_id=problem_descriptor.location.block_id),
+            html_fragment.content
+        )
+
     @XBlock.register_temp_plugin(DetachedXBlock, identifier='detached-block')
     def test_staff_debug_info_disabled_for_detached_blocks(self):
         """Staff markup should not be present on detached blocks."""
diff --git a/lms/djangoapps/grades/tests/test_transformer.py b/lms/djangoapps/grades/tests/test_transformer.py
index 04795425f4..4e3180f155 100644
--- a/lms/djangoapps/grades/tests/test_transformer.py
+++ b/lms/djangoapps/grades/tests/test_transformer.py
@@ -347,6 +347,35 @@ class GradesTransformerTestCase(CourseStructureTestCase):
             max_score=2,
         )
 
+    def test_max_score_for_invalid_dropdown_problem(self):
+        """
+        Verify that for an invalid dropdown problem, the max score is set to zero.
+        """
+        problem_data = u'''
+        <problem>
+            <optionresponse>
+              <p>You can use this template as a guide to the simple editor markdown and OLX markup to use for dropdown problems. Edit this component to replace this template with your own assessment.</p>
+            <label>Add the question text, or prompt, here. This text is required.</label>
+            <description>You can add an optional tip or note related to the prompt like this. </description>
+            <optioninput>
+                <option correct="False">an incorrect answer</option>
+                <option correct="True">the correct answer</option>
+                <option correct="True">an incorrect answer</option>
+              </optioninput>
+            </optionresponse>
+        </problem>
+        '''
+
+        blocks = self.build_course_with_problems(problem_data)
+        block_structure = get_course_blocks(self.student, blocks['course'].location, self.transformers)
+
+        self.assert_collected_transformer_block_fields(
+            block_structure,
+            blocks['problem'].location,
+            self.TRANSFORMER_CLASS_TO_TEST,
+            max_score=0,
+        )
+
     def test_course_version_not_collected_in_old_mongo(self):
         blocks = self.build_course_with_problems()
         block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)