gnu: python2-larch: Enable tests.

* gnu/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch: New
file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/python.scm (python2-larch)[source]: Use it.
[arguments]: Move 'check' phase to before 'build' phase.

gnu/local.mk

@@ -962,6 +962,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-genshi-fix-tests-on-python-3.5.patch	\
   %D%/packages/patches/python-genshi-isstring-helper.patch	\
   %D%/packages/patches/python-genshi-stripping-of-unsafe-script-tags.patch	\
+  %D%/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch \
   %D%/packages/patches/python-parse-too-many-fields.patch	\
   %D%/packages/patches/python2-rdflib-drop-sparqlwrapper.patch	\
   %D%/packages/patches/python-statsmodels-fix-tests.patch	\

gnu/packages/patches/python2-larch-coverage-4.0a6-compatibility.patch

@@ -0,0 +1,29 @@
+From ca548da9ba78ddee90779051210e3e89185e4f7d Mon Sep 17 00:00:00 2001
+From: Michel Alexandre Salim <michel@michel-slm.name>
+Date: Mon, 15 Feb 2016 23:03:42 +0700
+Subject: coverage-4.0a6 compatibility
+
+coverage 4.0a6 no longer generates .coverage file, so use -f when
+deleting .coverage to ensure deletion does not fail.
+---
+ Makefile | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+(limited to 'Makefile')
+
+diff --git a/Makefile b/Makefile
+index 7818f57..362c07f 100644
+--- a/Makefile
++++ b/Makefile
+@@ -23,7 +23,7 @@ fsck-larch.1: fsck-larch.1.in fsck-larch
+ 
+ check:
+ 	python -m CoverageTestRunner --ignore-missing-from=without-tests
+-	rm .coverage
++	rm -f .coverage
+ 	./insert-remove-test tempdir 100
+ 	rm -r tempdir larch.log
+ 	cmdtest tests
+-- 
+cgit v1.1
+

gnu/packages/python.scm

@@ -68,6 +68,7 @@
   #:use-module (gnu packages attr)
   #:use-module (gnu packages backup)
   #:use-module (gnu packages bash)
+  #:use-module (gnu packages check)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages crypto)
   #:use-module (gnu packages databases)
@@ -14193,12 +14194,26 @@ happens using the @code{logging} library.")
        (uri (string-append
              "http://git.liw.fi/cgi-bin/cgit/cgit.cgi/larch/snapshot/larch-"
              version ".tar.gz"))
+       (patches (search-patches
+                 "python2-larch-coverage-4.0a6-compatibility.patch"))
        (sha256
         (base32
          "1p4knkkavlqymgciz2wbcnfrdgdbafhg14maplnk4vbw0q8xs663"))))
     (build-system python-build-system)
     (arguments
-     `(#:python ,python-2))
+     `(#:python ,python-2
+       #:phases
+       (modify-phases %standard-phases
+         ;; check phase needs to be run before the build phase. If not,
+         ;; coverage-test-runner looks for tests for the built source files,
+         ;; and fails.
+         (delete 'check)
+         (add-before 'build 'check
+           (lambda _
+             (zero? (system* "make" "check")))))))
+    (native-inputs
+     `(("cmdtest" ,cmdtest)
+       ("python2-coverage-test-runner" ,python2-coverage-test-runner)))
     (propagated-inputs
      `(("python2-tracing" ,python2-tracing)))
     (home-page "https://liw.fi/larch/")