copy saferepr from pylib verbatim

Copied from b9da2ed6178cd37d4ed6b41f9fa8234dce96973f

testing/io/test_saferepr.py

@@ -0,0 +1,75 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import generators
+import py
+import sys
+
+saferepr = py.io.saferepr
+
+class TestSafeRepr:
+    def test_simple_repr(self):
+        assert saferepr(1) == '1'
+        assert saferepr(None) == 'None'
+
+    def test_maxsize(self):
+        s = saferepr('x'*50, maxsize=25)
+        assert len(s) == 25
+        expected = repr('x'*10 + '...' + 'x'*10)
+        assert s == expected
+
+    def test_maxsize_error_on_instance(self):
+        class A:
+            def __repr__(self):
+                raise ValueError('...')
+
+        s = saferepr(('*'*50, A()), maxsize=25)
+        assert len(s) == 25
+        assert s[0] == '(' and s[-1] == ')'
+
+    def test_exceptions(self):
+        class BrokenRepr:
+            def __init__(self, ex):
+                self.ex = ex
+                foo = 0
+            def __repr__(self):
+                raise self.ex
+        class BrokenReprException(Exception):
+            __str__ = None
+            __repr__ = None
+        assert 'Exception' in saferepr(BrokenRepr(Exception("broken")))
+        s = saferepr(BrokenReprException("really broken"))
+        assert 'TypeError' in s
+        assert 'TypeError' in saferepr(BrokenRepr("string"))
+
+        s2 = saferepr(BrokenRepr(BrokenReprException('omg even worse')))
+        assert 'NameError' not in s2
+        assert 'unknown' in s2
+
+    def test_big_repr(self):
+        from py._io.saferepr import SafeRepr
+        assert len(saferepr(range(1000))) <= \
+               len('[' + SafeRepr().maxlist * "1000" + ']')
+
+    def test_repr_on_newstyle(self):
+        class Function(object):
+            def __repr__(self):
+                return "<%s>" %(self.name)
+        try:
+            s = saferepr(Function())
+        except Exception:
+            py.test.fail("saferepr failed for newstyle class")
+
+    def test_unicode(self):
+        val = py.builtin._totext('£€', 'utf-8')
+        reprval = py.builtin._totext("'£€'", 'utf-8')
+        assert saferepr(val) == reprval
+
+def test_unicode_handling():
+    value = py.builtin._totext('\xc4\x85\xc4\x87\n', 'utf-8').encode('utf8')
+    def f():
+        raise Exception(value)
+    excinfo = py.test.raises(Exception, f)
+    s = str(excinfo)
+    if sys.version_info[0] < 3:
+        u = unicode(excinfo)
+