CI: Verify "go mod tidy" in every go module

We create a simple helper script, and call it from the github action.

Author: justinsb

.github/workflows/main.yml

@@ -47,7 +47,7 @@ jobs:
 
       - uses: actions/checkout@v2
 
-      - run: go mod tidy
+      - run: dev/format-gomod
 
       - run: |
           changes=$(git status --porcelain)

dev/format-gomod

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+# Copyright 2022 The Kubernetes Authors.
+#
+# 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.
+
+
+# CI script to run all the test commands
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+# cd to the repo root
+REPO_ROOT=$(git rev-parse --show-toplevel)
+cd "${REPO_ROOT}"
+
+# Run go mod tidy in each go module
+for module in $(find . -name "go.mod"); do
+  dir="$(dirname ${module})"
+  pushd "${dir}"
+    go mod tidy
+  popd
+done