chore: add Makefile and a precommit check

.github/workflows/go.yml

@@ -20,3 +20,5 @@ jobs:
         run: go build -v ./...
       - name: Test
         run: go test -v ./...
+      - name: Mod Tidy
+        run: go mod tidy && git diff --exit-code -- go.mod go.sum || (echo "go modules are not tidy, run 'go mod tidy'." && exit 1)

.github/workflows/golangci-lint.yml

@@ -12,4 +12,6 @@ jobs:
         uses: golangci/golangci-lint-action@v2
         with:
           # Required: the version of golangci-lint is required and must be specified without patch version: we always use the latest patch version.
+          # NOTICE: golangci-lint version should be the same as go.mod. When upgrading, also update go.mod by:
+          # go get github.com/golangci/golangci-lint@v1.29
           version: v1.29

Makefile

@@ -0,0 +1,29 @@
+# Copyright 2022 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# All of these should pass before sending a PR.
+precommit: test lint tidy
+
+test: FORCE
+	go test ./...
+
+lint:  FORCE
+# Note, golangci-lint version is pinned in go.mod. When upgrading, also
+# upgrade version in .github/workflows/golangci-lint.yml.
+	go run github.com/golangci/golangci-lint/cmd/golangci-lint run -v
+
+tidy: FORCE
+	go mod tidy
+
+FORCE: ;

go.mod

@@ -4,6 +4,7 @@ go 1.16
 
 require (
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
+	github.com/golangci/golangci-lint v1.29.0
 	github.com/google/go-cmp v0.5.6
 	github.com/google/go-replayers/httpreplay v1.0.0
 	github.com/google/licenseclassifier v0.0.0-20210722185704-3043a050f148