Added unittest + basic python and lua unittests (#174)

---------

Co-authored-by: Danymat <d.danymat@gmail.com>

Makefile

@@ -1,5 +1,17 @@
+TESTS_INIT=tests/minimal_init.lua
+TESTS_DIR=tests/
+
+.PHONY: test
+
 documentation:
 	nvim --headless --noplugin -u ./scripts/minimal_init.vim -c "lua MiniDoc.generate()" -c "qa!"
 
 tag:
 	./scripts/generate_tag.sh
+
+test:
+	@nvim \
+		--headless \
+		--noplugin \
+		-u ${TESTS_INIT} \
+		-c "PlenaryBustedDirectory ${TESTS_DIR} { minimal_init = '${TESTS_INIT}' }"