Assert course equality in bulk, so that all differences are displayed

common/lib/xmodule/xmodule/tests/__init__.py

@@ -12,6 +12,7 @@ import os
 import pprint
 import unittest
 
+from contextlib import contextmanager
 from mock import Mock
 from path import path
 
@@ -174,12 +175,64 @@ def map_references(value, field, actual_course_key):
     return value
 
 
-class CourseComparisonTest(unittest.TestCase):
+class BulkAssertionManager(object):
+    """
+    This provides a facility for making a large number of assertions, and seeing all of
+    the failures at once, rather than only seeing single failures.
+    """
+    def __init__(self, test_case):
+        self._equal_expected = []
+        self._equal_actual = []
+        self._test_case = test_case
+
+    def assertEqual(self, expected, actual, description=None):
+        if description is None:
+            description = "{!r} does not equal {!r}".format(expected, actual)
+        if expected != actual:
+            self._equal_expected.append((description, expected))
+            self._equal_actual.append((description, actual))
+
+    def run_assertions(self):
+        self._test_case.assertEqual(self._equal_expected, self._equal_actual)
+
+
+class BulkAssertionTest(unittest.TestCase):
+    """
+    This context manager provides a BulkAssertionManager to assert with,
+    and then calls `run_assertions` at the end of the block to validate all
+    of the assertions.
+    """
+
+    def setUp(self, *args, **kwargs):
+        super(BulkAssertionTest, self).setUp(*args, **kwargs)
+        self._manager = None
+
+    @contextmanager
+    def bulk_assertions(self):
+        if self._manager:
+            yield
+        else:
+            try:
+                self._manager = BulkAssertionManager(self)
+                yield
+            finally:
+                self._manager.run_assertions()
+                self._manager = None
+
+    def assertEqual(self, expected, actual, message=None):
+        if self._manager is not None:
+            self._manager.assertEqual(expected, actual, message)
+        else:
+            super(BulkAssertionTest, self).assertEqual(expected, actual, message)
+
+
+class CourseComparisonTest(BulkAssertionTest):
     """
     Mixin that has methods for comparing courses for equality.
     """
 
     def setUp(self):
+        super(CourseComparisonTest, self).setUp()
         self.field_exclusions = set()
         self.ignored_asset_keys = set()
 
@@ -235,6 +288,7 @@ class CourseComparisonTest(unittest.TestCase):
                 self._assertCoursesEqual(expected_items, actual_items, actual_course_key, expect_drafts=True)
 
     def _assertCoursesEqual(self, expected_items, actual_items, actual_course_key, expect_drafts=False):
+        with self.bulk_assertions():
             self.assertEqual(len(expected_items), len(actual_items))
 
             actual_item_map = {
@@ -339,6 +393,8 @@ class CourseComparisonTest(unittest.TestCase):
         expected_content, expected_count = expected_store.get_all_content_for_course(expected_course_key)
         actual_content, actual_count = actual_store.get_all_content_for_course(actual_course_key)
 
+        with self.bulk_assertions():
+
             self.assertEqual(expected_count, actual_count)
             self._assertAssetsEqual(expected_course_key, expected_content, actual_course_key, actual_content)