Show full repr for assert a==b with -vv

AUTHORS

@@ -176,6 +176,7 @@ Oliver Bestwalter
 Omar Kohl
 Omer Hadari
 Ondřej Súkup
+Oscar Benjamin
 Patrick Hayes
 Paweł Adamczak
 Pedro Algarvio

changelog/2256.bugfix

@@ -0,0 +1 @@
+Show full repr with ``assert a==b`` and ``-vv``.

src/_pytest/assertion/util.py

@@ -151,6 +151,8 @@ def isiterable(obj):
                 elif type(left) == type(right) and (isdatacls(left) or isattrs(left)):
                     type_fn = (isdatacls, isattrs)
                     explanation = _compare_eq_cls(left, right, verbose, type_fn)
+                elif verbose:
+                    explanation = _compare_eq_verbose(left, right, verbose)
                 if isiterable(left) and isiterable(right):
                     expl = _compare_eq_iterable(left, right, verbose)
                     if explanation is not None:
@@ -236,6 +238,18 @@ def escape_for_readable_diff(binary_text):
     return explanation
 
 
+def _compare_eq_verbose(left, right, verbose=False):
+    keepends = True
+    left_lines = repr(left).splitlines(keepends)
+    right_lines = repr(right).splitlines(keepends)
+
+    explanation = []
+    explanation += [u"-" + line for line in left_lines]
+    explanation += [u"+" + line for line in right_lines]
+
+    return explanation
+
+
 def _compare_eq_iterable(left, right, verbose=False):
     if not verbose:
         return [u"Use -v to get the full diff"]

testing/test_assertion.py

@@ -488,6 +488,29 @@ def test_list_tuples(self):
         expl = callequal([(1, 2)], [])
         assert len(expl) > 1
 
+    def test_repr_verbose(self):
+        class Nums:
+            def __init__(self, nums):
+                self.nums = nums
+            def __repr__(self):
+                return str(self.nums)
+
+        list_x = list(range(5000))
+        list_y = list(range(5000))
+        list_y[len(list_y)//2] = 3
+        nums_x = Nums(list_x)
+        nums_y = Nums(list_y)
+
+        assert callequal(nums_x, nums_y) is None
+
+        expl = callequal(nums_x, nums_y, verbose=1)
+        assert '-' + repr(nums_x) in expl
+        assert '+' + repr(nums_y) in expl
+
+        expl = callequal(nums_x, nums_y, verbose=2)
+        assert '-' + repr(nums_x) in expl
+        assert '+' + repr(nums_y) in expl
+
     def test_list_bad_repr(self):
         class A(object):
             def __repr__(self):