[hw-2] add tests, coverage, benchmarks

cart/Makefile

@@ -1,8 +1,14 @@
 BINDIR=${CURDIR}/bin
 PACKAGE=route256/cart
 
+PKGS = $(shell go list ./... | grep -vE 'mock|config|generated|header|document|internal/pb')
+
 bindir:
 	mkdir -p ${BINDIR}
 
 build: bindir
 	echo "build cart"
+
+coverage:
+	@go test -race -coverprofile=coverage.txt -covermode=atomic $(PKGS)
+	@go tool cover -html=coverage.txt -o coverage.html