Add code coverage action in pipeline

.github/workflows/go.yml

@@ -83,3 +83,17 @@ jobs:
           bin/golangci-lint run -c=.golangci-required.yml --out-format=line-number | env REVIEWDOG_GITHUB_API_TOKEN=${{ secrets.GITHUB_TOKEN }} bin/reviewdog -f=golangci-lint -level=error -reporter=github-pr-check
           bin/golangci-lint run -c=.golangci.yml --out-format=line-number | env REVIEWDOG_GITHUB_API_TOKEN=${{ secrets.GITHUB_TOKEN }} bin/reviewdog -f=golangci-lint -level=error -reporter=github-pr-review
           make check-license
+
+      - name: Run code coverage
+        run: |
+          TEST_MONGODB_IMAGE=${{ matrix.image }} make test-cluster
+          make test-cover
+          make test-cluster-clean
+
+      - name: Upload coverage results
+        uses: codecov/codecov-action@v3
+        with:
+          file: cover.out
+          flags: agent
+          env_vars: GO_VERSION,TEST_MONGODB_IMAGE
+          fail_ci_if_error: false

.gitignore

@@ -1,8 +1,12 @@
 .dist
 .env
+
 .vscode/
 .idea
+
 bin
 build
 dist
+
+cover.out
 mongodb_exporter

Makefile

@@ -67,7 +67,7 @@ endef
 env:
 	@echo $(TEST_ENV) | tr ' ' '\n' >.env
 
-init:                       ## Install linters.
+init:                       ## Install linters
 	cd tools && go generate -x -tags=tools
 
 build:                      ## Compile using plain go build
@@ -81,30 +81,33 @@ release:                      ## Build the binaries using goreleaser
 
 FILES = $(shell find . -type f -name '*.go' -not -path "./vendor/*")
 
-format:                     ## Format source code.
+format:                     ## Format source code
 	go mod tidy
 	bin/gofumpt -l -w $(FILES)
 	bin/gci write --section Standard --section Default --section "Prefix(github.com/percona/mongodb_exporter)" .
 
 check:                      ## Run checks/linters
 	bin/golangci-lint run
 
-check-license:              ## Check license in headers.
+check-license:              ## Check license in headers
 	@go run .github/check-license.go
 
-help:                       ## Display this help message.
+help:                       ## Display this help message
 	@echo "Please use \`make <target>\` where <target> is one of:"
 	@grep '^[a-zA-Z]' $(MAKEFILE_LIST) | \
 	awk -F ':.*?## ' 'NF==2 {printf "  %-26s%s\n", $$1, $$2}'
 
-test: env                   ## Run all tests.
+test: env                   ## Run all tests
 	go test -v -count 1 -timeout 30s ./...
 
-test-race: env              ## Run all tests with race flag.
+test-race: env              ## Run all tests with race flag
 	go test -race -v -timeout 30s ./...
 
-test-cluster: env           ## Starts MongoDB test cluster. Use env var TEST_MONGODB_IMAGE to set flavor and version. Example: TEST_MONGODB_IMAGE=mongo:3.6 make test-cluster
+test-cover: env              ## Run tests and collect cross-package coverage information
+	go test -race -timeout 30s -coverprofile=cover.out -covermode=atomic -coverpkg=./... ./...
+
+test-cluster: env           ## Starts MongoDB test cluster. Use env var TEST_MONGODB_IMAGE to set flavor and version. Example: TEST_MONGODB_IMAGE=mongo:4.4 make test-cluster
 	docker-compose up -d
 
-test-cluster-clean: env     ## Stops MongoDB test cluster.
+test-cluster-clean: env     ## Stops MongoDB test cluster
 	docker-compose down --remove-orphans