From 61c87dc56663cdb7d31b24c202ea54ecf3e28522 Mon Sep 17 00:00:00 2001
From: Tom Viner <tom@viner.tv>
Date: Fri, 24 Jun 2016 12:44:06 +0200
Subject: [PATCH] Fixes #1503 no longer collapse false explanations

---
 _pytest/assertion/util.py     | 33 ---------------------------------
 testing/test_assertrewrite.py | 34 ++++++++++++++++++++--------------
 2 files changed, 20 insertions(+), 47 deletions(-)

diff --git a/_pytest/assertion/util.py b/_pytest/assertion/util.py
index 8bf425caf48..2481cf34ccd 100644
--- a/_pytest/assertion/util.py
+++ b/_pytest/assertion/util.py
@@ -38,44 +38,11 @@ def format_explanation(explanation):
     displaying diffs.
     """
     explanation = ecu(explanation)
-    explanation = _collapse_false(explanation)
     lines = _split_explanation(explanation)
     result = _format_lines(lines)
     return u('\n').join(result)
 
 
-def _collapse_false(explanation):
-    """Collapse expansions of False
-
-    So this strips out any "assert False\n{where False = ...\n}"
-    blocks.
-    """
-    where = 0
-    while True:
-        start = where = explanation.find("False\n{False = ", where)
-        if where == -1:
-            break
-        level = 0
-        prev_c = explanation[start]
-        for i, c in enumerate(explanation[start:]):
-            if prev_c + c == "\n{":
-                level += 1
-            elif prev_c + c == "\n}":
-                level -= 1
-                if not level:
-                    break
-            prev_c = c
-        else:
-            raise AssertionError("unbalanced braces: %r" % (explanation,))
-        end = start + i
-        where = end
-        if explanation[end - 1] == '\n':
-            explanation = (explanation[:start] + explanation[start+15:end-1] +
-                           explanation[end+1:])
-            where -= 17
-    return explanation
-
-
 def _split_explanation(explanation):
     """Return a list of individual lines in the explanation
 
diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py
index f43c424ca94..a47d8a75f96 100644
--- a/testing/test_assertrewrite.py
+++ b/testing/test_assertrewrite.py
@@ -213,10 +213,12 @@ def x():
             return False
         def f():
             assert x() and x()
-        assert getmsg(f, {"x" : x}) == "assert (x())"
+        assert getmsg(f, {"x" : x}) == """assert (False)
+ +  where False = x()"""
         def f():
             assert False or x()
-        assert getmsg(f, {"x" : x}) == "assert (False or x())"
+        assert getmsg(f, {"x" : x}) == """assert (False or False)
+ +  where False = x()"""
         def f():
             assert 1 in {} and 2 in {}
         assert getmsg(f) == "assert (1 in {})"
@@ -299,27 +301,34 @@ def g(a=42, *args, **kwargs):
         ns = {"g" : g}
         def f():
             assert g()
-        assert getmsg(f, ns) == """assert g()"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g()"""
         def f():
             assert g(1)
-        assert getmsg(f, ns) == """assert g(1)"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1)"""
         def f():
             assert g(1, 2)
-        assert getmsg(f, ns) == """assert g(1, 2)"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, 2)"""
         def f():
             assert g(1, g=42)
-        assert getmsg(f, ns) == """assert g(1, g=42)"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, g=42)"""
         def f():
             assert g(1, 3, g=23)
-        assert getmsg(f, ns) == """assert g(1, 3, g=23)"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(1, 3, g=23)"""
         def f():
             seq = [1, 2, 3]
             assert g(*seq)
-        assert getmsg(f, ns) == """assert g(*[1, 2, 3])"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(*[1, 2, 3])"""
         def f():
             x = "a"
             assert g(**{x : 2})
-        assert getmsg(f, ns) == """assert g(**{'a': 2})"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = g(**{'a': 2})"""
 
     def test_attribute(self):
         class X(object):
@@ -332,7 +341,8 @@ def f():
         def f():
             x.a = False  # noqa
             assert x.a   # noqa
-        assert getmsg(f, ns) == """assert x.a"""
+        assert getmsg(f, ns) == """assert False
+ +  where False = x.a"""
 
     def test_comparisons(self):
         def f():
@@ -710,7 +720,3 @@ def test_long_repr():
     """)
     result = testdir.runpytest()
     assert 'unbalanced braces' not in result.stdout.str()
-
-
-def test_collapse_false_unbalanced_braces():
-    util._collapse_false('some text{ False\n{False = some more text\n}')