dev-python/isodate: fix test phase

Bug: https://bugs.gentoo.org/607184
Package-Manager: Portage-2.3.6_p1, Repoman-2.3.2_p69

dev-python/isodate/isodate-0.5.4.ebuild

@@ -19,15 +19,5 @@ IUSE=""
 DEPEND="dev-python/setuptools[${PYTHON_USEDEP}]"
 
 python_test() {
-	local testfile
-	pushd "${BUILD_DIR}"/lib/ || die
-	for test in ${PN}/tests/test_*.py; do
-		if ! "${PYTHON}" "${testfile}"; then
-			die "Test ${testfile} failed under ${EPYTHON}"
-		fi
-	done
-
-	# Give some order to the output salad.
-	einfo "Testsuite passed under ${EPYTHON}";
-	einfo ""
+	${EPYTHON} -m unittest discover -v -s "${BUILD_DIR}/lib" || die "Testing failed with ${EPYTHON}"
 }