Implement a workflow that lints changed markdown files. (#39707)

* Implement a workflow that lints changed markdown files.

* Supposed to pipe the contents of files not file names.

* Fix typos in the command.

* Test changing a markdown file.

* Use a more reliable action to determine changed files.

* Adjust glob.

* Try a faster setup approach with wp-scripts installed globally

* std in does not work with wp scripts, run markdownlint directly, improve output for multiple file failures

* Try simplify the script.

* Try basic colorizing to help read output.

* separate output with a line, remove ignore because we use stdin for this.

* Play around with separation of output.

* Try use ccze to colorize output more simply.

* Remove attempt at colorizing.

* Copy config from Gutenberg to match, try coloring again.

* Do not fail after first failure found.

* Try capture errors.

* Capture in var and capture error.

* Now we capture, add back colors.

* Minor formatting adjustments.

* More minor formatting improvements.

* Add a second file to test multiple lints.

* Revert changes to md files to show a run with no lint issues.

* Test fixing a markdown file to have a lint pass with changes.

* Revert testing changes to markdown file.

* Revert lock changes we dont have dep changes in this PR.

.github/workflows/pr-lint-markdown.yml

@@ -0,0 +1,64 @@
+name: MarkdownLint on PR
+on:
+    pull_request:
+        paths-ignore:
+            - '**/changelog/**'
+
+jobs:
+    lint:
+        runs-on: ubuntu-latest
+
+        steps:
+            - uses: actions/checkout@v3
+              with:
+                  fetch-depth: 2
+
+            - name: Get changed files
+              id: changed-files
+              uses: tj-actions/changed-files@v37
+              with:
+                  files: |
+                      **/*.md
+
+            - name: Setup PNPM
+              uses: pnpm/action-setup@c3b53f6a16e57305370b4ae5a540c2077a1d50dd
+              with:
+                  version: '8.6.7'
+
+            - name: Setup Node
+              uses: actions/setup-node@64ed1c7eab4cce3362f8c340dee64e5eaeef8f7c
+              with:
+                  node-version-file: .nvmrc
+                  cache: pnpm
+                  registry-url: 'https://registry.npmjs.org'
+
+            - name: Install prerequisites
+              run: |
+                  pnpm i -g markdownlint-cli
+
+            - name: Lint changed markdown files
+              run: |
+                  RED="\e[1;31m"
+                  GREEN="\e[1;32m"
+                  NC="\e[0m"
+                  set -e
+                  rc=0
+                  changed_files="${{ steps.changed-files.outputs.all_changed_files  }}"
+                  if [ -n "$changed_files" ]; then
+                    lint_results=""
+                    for file in $changed_files; do
+                      lint_result=$( { cat "$file" | markdownlint --stdin ; } 2>&1 ) || rc="$?"
+                      if [ $rc -ne 0 ]; then
+                        lint_results="$lint_results\n>>>Linting failed for file: $file <<<\n$lint_result\n--------"
+                      fi
+                    done
+                    if [ $rc -ne 0 ]; then
+                      echo -e "${RED}Linting failed for one or more files${NC}"
+                      echo -e "$lint_results"
+                      exit 1
+                    else
+                      echo -e "${GREEN}Linting successful for all files.${NC}"
+                    fi
+                  else
+                    echo "No markdown files changed."
+                  fi

.markdownlint.json

@@ -0,0 +1,8 @@
+{
+	"default": true,
+	"MD003": { "style": "atx" },
+	"MD007": { "indent": 4 },
+	"MD013": { "line_length": 9999 },
+	"no-hard-tabs": false,
+	"whitespace": false
+}