improve assert re-inteprpretation for comparisons

--HG--
branch : 1.0.x

CHANGELOG

@@ -1,6 +1,9 @@
 Changes between 1.0.0b8 and 1.0.0b9
 =====================================
 
+* make assert-reinterpretation work better with comparisons not 
+  returning bools (reported with numpy from thanks maciej fijalkowski)
+
 * reworked per-test output capturing into the pytest_iocapture.py plugin 
   and thus removed capturing code from config object 
 

py/magic/exprinfo.py

@@ -122,6 +122,10 @@ class Compare(Interpretable):
         expr = Interpretable(self.expr)
         expr.eval(frame)
         for operation, expr2 in self.ops:
+            if hasattr(self, 'result'):
+                # shortcutting in chained expressions
+                if not frame.is_true(self.result):
+                    break
             expr2 = Interpretable(expr2)
             expr2.eval(frame)
             self.explanation = "%s %s %s" % (
@@ -135,8 +139,6 @@ class Compare(Interpretable):
                 raise
             except:
                 raise Failure(self)
-            if not frame.is_true(self.result):
-                break
             expr = expr2
 
 class And(Interpretable):

py/magic/testing/test_exprinfo.py

@@ -131,3 +131,26 @@ def test_inconsistent_assert_result(testdir):
     s = result.stdout.str()
     assert s.find("re-run") != -1
 
+def test_twoarg_comparison_does_not_call_nonzero():
+    # this arises e.g. in numpy array comparisons 
+    class X(object):
+        def __eq__(self, other):
+            return self
+
+        def __nonzero__(self):
+            raise ValueError
+
+        def all(self):
+            return False
+
+    def f():
+        a = X()
+        b = X()
+        assert (a == b).all()
+
+    excinfo = getexcinfo(AssertionError, f)
+    msg = getmsg(excinfo)
+    print msg
+    assert "re-run" not in msg
+    assert "ValueError" not in msg
+