return U diff for equal multiline strings when op_u enabled

Author: mr-mixas

nested_diff/handlers.py

@@ -711,7 +711,7 @@ def diff(self, differ, a, b):
         if diff:
             return equal, {'D': diff, 'E': self.extension_id}
 
-        return equal, {}
+        return equal, {'U': a} if differ.op_u else {}
 
     def patch(self, patcher, target, diff):  # noqa U100
         """Patch text (multiline string).

tests/data/formatters/HtmlFormatter.py

@@ -378,6 +378,9 @@
         'result': '<div class="nDvD"></div>',
     },
     'text_equal': {
+        'result': '<div class="nDvD"><div>  <div class="nDvU">&#x27;A\\nB\\nC&#x27;</div></div></div>',
+    },
+    'text_equal_noU': {
         'result': '<div class="nDvD"></div>',
     },
     'text_lcs': {

tests/data/formatters/TermFormatter.py

@@ -378,6 +378,9 @@
         'result': '',
     },
     'text_equal': {
+        'result': "  'A\\nB\\nC'\x1b[0m\n",
+    },
+    'text_equal_noU': {
         'result': '',
     },
     'text_lcs': {

tests/data/formatters/TextFormatter.py

@@ -378,6 +378,9 @@
         'result': '',
     },
     'text_equal': {
+        'result': "  'A\\nB\\nC'\n",
+    },
+    'text_equal_noU': {
         'result': '',
     },
     'text_lcs': {

tests/data/specific.py

@@ -96,6 +96,12 @@ def get_tests():
             'assert_func': lambda a, b: dumps(a) == dumps(b),
         },
         'text_equal': {
+            'a': 'A\nB\nC',
+            'b': 'A\nB\nC',
+            'diff': {'U': 'A\nB\nC'},
+            'handlers': {TextHandler: {'context': 3}},
+        },
+        'text_equal_noU': {
             'a': 'A\nB\nC',
             'b': 'A\nB\nC',
             'diff': {},