test: add linting stage

Statically validate module code and tests with luacheck [1]. Run linting
stage as a first step of regression tests.

1. https://github.com/tarantool/luacheck

Part of tarantool/tarantool#7726

Author: DifferentialOrange

.github/workflows/reusable_testing.yml

@@ -28,4 +28,6 @@ jobs:
         # dependencies when migrating to other OS version.
         run: sudo dpkg -i tarantool*.deb
 
+      - run: make lint
+
       - run: make test

.github/workflows/test.yml

@@ -17,6 +17,9 @@ jobs:
         with:
           tarantool-version: ${{ matrix.tarantool }}
 
+      - name: Run static analysis
+        run: make lint
+
       - name: Run regression testing
         run: make test
 

.luacheckrc

@@ -0,0 +1,4 @@
+include_files = {'**/*.lua', '*.luacheckrc', '*.rockspec'}
+exclude_files = {'.rocks/', 'tmp/', 'build/'}
+max_line_length = 120
+redefined = false

Makefile

@@ -5,12 +5,17 @@ endif
 
 .PHONY: all
 all:
-	@echo "Available commands: .rocks, test, perf, clean"
+	@echo "Available commands: .rocks, lint, test, perf, clean"
 
 .rocks: rockspecs/checks-scm-1.rockspec
 	$(TTCTL) rocks make
+	$(TTCTL) rocks install luacheck 0.26.0
 	$(TTCTL) rocks install luatest 0.5.7
 
+.PHONY: lint
+lint: .rocks
+	.rocks/bin/luacheck .
+
 .PHONY: test
 test: .rocks
 	.rocks/bin/luatest -c -v ./test.lua