Update tests.

Keep watching a workflow with modularity-testing-framework will be stable.

tests/Makefile

@@ -1,7 +1,14 @@
-MODULE_LINT=/usr/share/moduleframework/tools/modulelint.py
-# --filter-by-tags=-WIP: ignore WIP tag test that have a issue on F25 avocado.
-CMD=python -m avocado run --filter-by-tags=-WIP $(MODULE_LINT) *.py
-
+# A workflow with modularity-testing-framework is still uncertain.
+# Only nspawn is actually used.
+# https://meta-test-family.readthedocs.io/en/latest/index.html
 #
-all:
-	$(CMD)
+# Installation
+# $ sudo dnf install modularity-testing-framework python2-avocado
+# $ sudo /usr/bin/pip install behave
+test:
+	mtf-generator
+	MODULE=nspawn \
+	python -d -m avocado run \
+		--filter-by-tags=-WIP \
+		/usr/share/moduleframework/tools/modulelint.py \
+		*.py