Merge pull request #2738 from bobbypage/presubmit-tidy

Check go mod tidy as part of presubmit and CI

Makefile

@@ -91,6 +91,8 @@ docker-build:
 presubmit: vet
 	@echo ">> checking go formatting"
 	@./build/check_gofmt.sh
+	@echo ">> checking go mod tidy"
+	@./build/check_gotidy.sh
 	@echo ">> checking file boilerplate"
 	@./build/check_boilerplate.sh
 

build/check_gotidy.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# Copyright 2020 Google Inc. All rights reserved.
+#
+# 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
+#
+#     http://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.
+
+# TODO(bobbypage): Replace this with `go mod tidy --check` when it exists:
+# https://github.com/golang/go/issues/27005.
+
+# Checks if go mod tidy changes are needed for a given go module.
+# If changes are needed, prints the diff and exits 1 status code.
+# Arguments:
+#   Directory of go module
+function lint_gotidy() {
+    MODULE_DIRECTORY="$1"
+
+    pushd "${MODULE_DIRECTORY}" > /dev/null
+    TMP_GOMOD=$(mktemp)
+    TMP_GOSUM=$(mktemp)
+
+    # Make a copy of the current files
+    cp go.mod "${TMP_GOMOD}"
+    cp go.sum "${TMP_GOSUM}"
+
+    go mod tidy
+
+    DIFF_MOD=$(diff -u "${TMP_GOMOD}" go.mod)
+    DIFF_SUM=$(diff -u "${TMP_GOSUM}" go.sum)
+
+    # Copy the files back
+    cp "${TMP_GOMOD}" go.mod
+    cp "${TMP_GOSUM}" go.sum
+
+    if [[ -n "${DIFF_MOD}" || -n "${DIFF_SUM}" ]]; then
+        echo "go tidy changes are needed; please run make tidy"
+        echo "go.mod diff:"
+        echo "${DIFF_MOD}"
+        echo "go.sum diff:"
+        echo "${DIFF_SUM}"
+        exit 1
+    fi
+
+    popd > /dev/null
+}
+
+# Check if go mod tidy changes needed on main module
+lint_gotidy "."
+
+# Check if go mod tidy changes needed on cmd module
+lint_gotidy "cmd"