Issue #10242: backport of more fixes to unittest.TestCase.assertItemsEqual

Lib/unittest/util.py

@@ -1,4 +1,6 @@
 """Various utility functions."""
+from collections import namedtuple, OrderedDict
+
 
 __unittest = True
 
@@ -92,3 +94,63 @@ def unorderable_list_difference(expected, actual, ignore_duplicate=False):
 
     # anything left in actual is unexpected
     return missing, actual
+
+_Mismatch = namedtuple('Mismatch', 'actual expected value')
+
+def _count_diff_all_purpose(actual, expected):
+    'Returns list of (cnt_act, cnt_exp, elem) triples where the counts differ'
+    # elements need not be hashable
+    s, t = list(actual), list(expected)
+    m, n = len(s), len(t)
+    NULL = object()
+    result = []
+    for i, elem in enumerate(s):
+        if elem is NULL:
+            continue
+        cnt_s = cnt_t = 0
+        for j in range(i, m):
+            if s[j] == elem:
+                cnt_s += 1
+                s[j] = NULL
+        for j, other_elem in enumerate(t):
+            if other_elem == elem:
+                cnt_t += 1
+                t[j] = NULL
+        if cnt_s != cnt_t:
+            diff = _Mismatch(cnt_s, cnt_t, elem)
+            result.append(diff)
+
+    for i, elem in enumerate(t):
+        if elem is NULL:
+            continue
+        cnt_t = 0
+        for j in range(i, n):
+            if t[j] == elem:
+                cnt_t += 1
+                t[j] = NULL
+        diff = _Mismatch(0, cnt_t, elem)
+        result.append(diff)
+    return result
+
+def _ordered_count(iterable):
+    'Return dict of element counts, in the order they were first seen'
+    c = OrderedDict()
+    for elem in iterable:
+        c[elem] = c.get(elem, 0) + 1
+    return c
+
+def _count_diff_hashable(actual, expected):
+    'Returns list of (cnt_act, cnt_exp, elem) triples where the counts differ'
+    # elements must be hashable
+    s, t = _ordered_count(actual), _ordered_count(expected)
+    result = []
+    for elem, cnt_s in s.items():
+        cnt_t = t.get(elem, 0)
+        if cnt_s != cnt_t:
+            diff = _Mismatch(cnt_s, cnt_t, elem)
+            result.append(diff)
+    for elem, cnt_t in t.items():
+        if elem not in s:
+            diff = _Mismatch(0, cnt_t, elem)
+            result.append(diff)
+    return result