gnu: python-testtools: Fix regression in test suite.

* gnu/packages/check.scm (python-testtools)[source]: Add patch.
* gnu/packages/patches/python-testtools.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.

gnu/local.mk

@@ -1087,6 +1087,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-configobj-setuptools.patch	\
   %D%/packages/patches/python-faker-fix-build-32bit.patch	\
   %D%/packages/patches/python-mox3-python3.6-compat.patch	\
+  %D%/packages/patches/python-testtools.patch			\
   %D%/packages/patches/python-paste-remove-website-test.patch	\
   %D%/packages/patches/python-paste-remove-timing-test.patch	\
   %D%/packages/patches/python-pycrypto-CVE-2013-7459.patch	\

gnu/packages/check.scm

@@ -879,7 +879,8 @@ subprocess and see the output as well as any file modifications.")
        (uri (pypi-uri "testtools" version))
        (sha256
         (base32
-         "0n8519lk8aaa91vymz842831181wf7fss98hyllhygi3z1nfq9sq"))))
+         "0n8519lk8aaa91vymz842831181wf7fss98hyllhygi3z1nfq9sq"))
+       (patches (search-patches "python-testtools.patch"))))
     (build-system python-build-system)
     (arguments '(#:tests? #f))
     (propagated-inputs

gnu/packages/patches/python-testtools.patch

@@ -0,0 +1,57 @@
+https://github.com/testing-cabal/testtools/commit/29004731f9c480b7c44a9c2605513d50d372898f.patch
+Should be fixed in the next release
+
+From 29004731f9c480b7c44a9c2605513d50d372898f Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Miro=20Hron=C4=8Dok?= <miro@hroncok.cz>
+Date: Thu, 17 May 2018 17:52:26 +0200
+Subject: [PATCH] Fix the tests on Python 3.7
+
+Exception's repr got changed not to include trailing comma
+
+Fixes https://github.com/testing-cabal/testtools/issues/270
+---
+ .travis.yml                                |  1 +
+ testtools/tests/matchers/test_exception.py | 11 +++++++++--
+ 2 files changed, 10 insertions(+), 2 deletions(-)
+
+diff --git a/.travis.yml b/.travis.yml
+index 7f1f4db7..784608e0 100644
+--- a/.travis.yml
++++ b/.travis.yml
+@@ -5,6 +5,7 @@ python:
+   - "3.4"
+   - "3.5"
+   - "3.6"
++  - "3.7-dev"
+   - "pypy"
+ 
+ install:
+diff --git a/testtools/tests/matchers/test_exception.py b/testtools/tests/matchers/test_exception.py
+index 6cd80af1..acd39252 100644
+--- a/testtools/tests/matchers/test_exception.py
++++ b/testtools/tests/matchers/test_exception.py
+@@ -32,15 +32,22 @@ class TestMatchesExceptionInstanceInterface(TestCase, TestMatchersInterface):
+     matches_matches = [error_foo]
+     matches_mismatches = [error_bar, error_base_foo]
+ 
++    if sys.version_info >= (3, 7):
++        # exception's repr has changed
++        _e = ''
++    else:
++        _e = ','
++
+     str_examples = [
+-        ("MatchesException(Exception('foo',))",
++        ("MatchesException(Exception('foo'%s))" % _e,
+          MatchesException(Exception('foo')))
+         ]
+     describe_examples = [
+         ("%r is not a %r" % (Exception, ValueError),
+          error_base_foo,
+          MatchesException(ValueError("foo"))),
+-        ("ValueError('bar',) has different arguments to ValueError('foo',).",
++        ("ValueError('bar'%s) has different arguments to ValueError('foo'%s)."
++         % (_e, _e),
+          error_bar,
+          MatchesException(ValueError("foo"))),
+         ]