Don't fail horribly on destructuring lambdas

Author: DRMacIver

scripts/basic-test.sh

@@ -17,6 +17,10 @@ for k, v in sorted(dict(os.environ).items()):
 
 python -m pytest tests/cover
 
+if [ "$(python -c 'import sys; print(sys.version_info.major == 2')" = "True" ] ; then
+    python -m pytest tests/py2
+fi
+
 if [ "$DARWIN" != true ]; then
   for f in tests/nocover/*.py; do
     python -m pytest $f

src/hypothesis/internal/reflection.py

@@ -205,7 +205,19 @@ def extract_lambda_source(f):
 
     """
     args = inspect.getargspec(f).args
-    if_confused = 'lambda %s: <unknown>' % (', '.join(args),)
+    arg_strings = []
+    bad_lambda = False
+    for a in args:
+        if isinstance(a, (tuple, list)):
+            arg_strings.append('(%s)' % (', '.join(a),))
+            bad_lambda = True
+        else:
+            assert isinstance(a, str)
+            arg_strings.append(a)
+
+    if_confused = 'lambda %s: <unknown>' % (', '.join(arg_strings),)
+    if bad_lambda:
+        return if_confused
     try:
         source = inspect.getsource(f)
     except IOError:

src/hypothesis/searchstrategy/reprwrapper.py

@@ -17,6 +17,7 @@
 from __future__ import division, print_function, absolute_import, \
     unicode_literals
 
+import inspect
 from hypothesis.searchstrategy.wrappers import WrapperStrategy
 
 
@@ -34,6 +35,8 @@ def __init__(self, strategy, representation):
         self.representation = representation
 
     def __repr__(self):
+        if inspect.isfunction(self.representation):
+            self.representation = self.representation()
         return self.representation
 
     def draw_parameter(self, random):

tests/py2/__init__.py

@@ -0,0 +1,25 @@
+# coding=utf-8
+
+# This file is part of Hypothesis (https://github.com/DRMacIver/hypothesis)
+
+# Most of this work is copyright (C) 2013-2015 David R. MacIver
+# (david@drmaciver.com), but it contains contributions by other. See
+# https://github.com/DRMacIver/hypothesis/blob/master/CONTRIBUTING.rst for a
+# full list of people who may hold copyright, and consult the git log if you
+# need to determine who owns an individual contribution.
+
+# This Source Code Form is subject to the terms of the Mozilla Public License,
+# v. 2.0. If a copy of the MPL was not distributed with this file, You can
+# obtain one at http://mozilla.org/MPL/2.0/.
+
+# END HEADER
+
+from __future__ import division, print_function, absolute_import, \
+    unicode_literals
+
+from hypothesis.internal.reflection import get_pretty_function_description
+
+
+def test_destructuring_lambdas():
+    assert get_pretty_function_description(lambda (x, y): 1) == \
+        'lambda (x, y): <unknown>'