fix: increase grades rounding precision

Enabling the rounding in openedx#16837 has been causing noticeable (up to 1 percentage
point) differences between non-rounded subsection grades and a total grade for
a course. This increases the grade precision to reduce the negative
implications of double rounding.

(cherry picked from commit 84d2ad9)

lms/djangoapps/grades/rest_api/v1/tests/test_views.py

@@ -302,7 +302,7 @@ def setUpClass(cls):
             + [
                 {
                     'category': 'Homework',
-                    'detail': 'Homework Average = 0%',
+                    'detail': 'Homework Average = 0.00%',
                     'label': 'HW Avg', 'percent': 0.0,
                     'prominent': True
                 }
@@ -332,21 +332,21 @@ def setUpClass(cls):
                 },
                 {
                     'category': 'Lab',
-                    'detail': 'Lab Average = 0%',
+                    'detail': 'Lab Average = 0.00%',
                     'label': 'Lab Avg',
                     'percent': 0.0,
                     'prominent': True
                 },
                 {
                     'category': 'Midterm Exam',
-                    'detail': 'Midterm Exam = 0%',
+                    'detail': 'Midterm Exam = 0.00%',
                     'label': 'Midterm',
                     'percent': 0.0,
                     'prominent': True
                 },
                 {
                     'category': 'Final Exam',
-                    'detail': 'Final Exam = 0%',
+                    'detail': 'Final Exam = 0.00%',
                     'label': 'Final',
                     'percent': 0.0,
                     'prominent': True

lms/djangoapps/grades/scores.py

@@ -162,8 +162,8 @@ def compute_percent(earned, possible):
      Returns the percentage of the given earned and possible values.
      """
     if possible > 0:
-        # Rounds to two decimal places.
-        return around(earned / possible, decimals=2)
+        # Rounds to four decimal places.
+        return around(earned / possible, decimals=4)
     else:
         return 0.0
 

lms/djangoapps/grades/tests/test_course_grade_factory.py

@@ -185,26 +185,26 @@ def test_course_grade_summary(self):
             'section_breakdown': [
                 {
                     'category': 'Homework',
-                    'detail': 'Homework 1 - Test Sequential X with an & Ampersand - 50% (1/2)',
+                    'detail': 'Homework 1 - Test Sequential X with an & Ampersand - 50.00% (1/2)',
                     'label': 'HW 01',
                     'percent': 0.5
                 },
                 {
                     'category': 'Homework',
-                    'detail': 'Homework 2 - Test Sequential A - 0% (0/1)',
+                    'detail': 'Homework 2 - Test Sequential A - 0.00% (0/1)',
                     'label': 'HW 02',
                     'percent': 0.0
                 },
                 {
                     'category': 'Homework',
-                    'detail': 'Homework Average = 25%',
+                    'detail': 'Homework Average = 25.00%',
                     'label': 'HW Avg',
                     'percent': 0.25,
                     'prominent': True
                 },
                 {
                     'category': 'NoCredit',
-                    'detail': 'NoCredit Average = 0%',
+                    'detail': 'NoCredit Average = 0.00%',
                     'label': 'NC Avg',
                     'percent': 0,
                     'prominent': True

lms/djangoapps/grades/tests/test_subsection_grade.py

@@ -14,7 +14,7 @@
 @ddt
 class SubsectionGradeTest(GradeTestBase):  # lint-amnesty, pylint: disable=missing-class-docstring
 
-    @data((50, 100, .50), (59.49, 100, .59), (59.51, 100, .60), (59.50, 100, .60), (60.5, 100, .60))
+    @data((50, 100, .5), (.5949, 100, .0059), (.5951, 100, .006), (.595, 100, .0059), (.605, 100, .006))
     @unpack
     def test_create_and_read(self, mock_earned, mock_possible, expected_result):
         with mock_get_score(mock_earned, mock_possible):

xmodule/graders.py

@@ -387,7 +387,7 @@ def grade(self, grade_sheet, generate_random_scores=False):
                     section_name = scores[i].display_name
 
                 percentage = scores[i].percent_graded
-                summary_format = "{section_type} {index} - {name} - {percent:.0%} ({earned:.3n}/{possible:.3n})"
+                summary_format = "{section_type} {index} - {name} - {percent:.2%} ({earned:.3n}/{possible:.3n})"
                 summary = summary_format.format(
                     index=i + self.starting_index,
                     section_type=self.section_type,
@@ -421,7 +421,7 @@ def grade(self, grade_sheet, generate_random_scores=False):
         if len(breakdown) == 1:
             # if there is only one entry in a section, suppress the existing individual entry and the average,
             # and just display a single entry for the section.
-            total_detail = "{section_type} = {percent:.0%}".format(
+            total_detail = "{section_type} = {percent:.2%}".format(
                 percent=total_percent,
                 section_type=self.section_type,
             )
@@ -430,7 +430,7 @@ def grade(self, grade_sheet, generate_random_scores=False):
                           'detail': total_detail, 'category': self.category, 'prominent': True}, ]
         else:
             # Translators: "Homework Average = 0%"
-            total_detail = _("{section_type} Average = {percent:.0%}").format(
+            total_detail = _("{section_type} Average = {percent:.2%}").format(
                 percent=total_percent,
                 section_type=self.section_type
             )