gnu: python-chardet: Enable tests.

* gnu/packages/python-xyz.scm (python-chardet) [source]: Add upstream patch.
[arguments]: Remove.
* gnu/packages/patches/python-chardet-3.0.4-pytest.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

Signed-off-by: Marius Bakke <marius@gnu.org>

gnu/local.mk

@@ -1491,6 +1491,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-argcomplete-1.11.1-fish31.patch	\
   %D%/packages/patches/python-axolotl-AES-fix.patch		\
   %D%/packages/patches/python-cairocffi-dlopen-path.patch	\
+  %D%/packages/patches/python-chardet-3.0.4-pytest.patch	\
   %D%/packages/patches/python-cross-compile.patch		\
   %D%/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch \
   %D%/packages/patches/python-configobj-setuptools.patch	\

gnu/packages/patches/python-chardet-3.0.4-pytest.patch

@@ -0,0 +1,15 @@
+Fix test failure with Pytest 4.
+
+Taken from upstream:
+https://github.com/chardet/chardet/commit/440828f8faafdb58700c64a9ea8f6a30b154c08b
+
+diff --git a/test.py b/test.py
+--- a/test.py
++++ b/test.py
+@@ -59,5 +59,5 @@ def gen_test_params():
+             full_path = join(path, file_name)
+             test_case = full_path, encoding
+             if full_path in EXPECTED_FAILURES:
+-                test_case = pytest.mark.xfail(test_case)
++                test_case = pytest.param(*test_case, marks=pytest.mark.xfail)
+             yield test_case

gnu/packages/python-xyz.scm

@@ -10059,14 +10059,13 @@ (define-public python-chardet
        (uri (pypi-uri "chardet" version))
        (sha256
         (base32
-         "1bpalpia6r5x1kknbk11p1fzph56fmmnp405ds8icksd3knr5aw4"))))
+         "1bpalpia6r5x1kknbk11p1fzph56fmmnp405ds8icksd3knr5aw4"))
+        (patches (search-patches "python-chardet-3.0.4-pytest.patch"))))
     (native-inputs
      `(("python-hypothesis" ,python-hypothesis)
        ("python-pytest" ,python-pytest)
        ("python-pytest-runner" ,python-pytest-runner)))
     (build-system python-build-system)
-    ;; XXX: Incompatible with Pytest 4: <https://github.com/chardet/chardet/issues/173>.
-    (arguments `(#:tests? #f))
     (home-page "https://github.com/chardet/chardet")
     (synopsis "Universal encoding detector for Python 2 and 3")
     (description