Add changelog lint script (#7320)

* Add changelog lint script

* Refactor lint script

* spell

* Fix indent

* fix templateComment

* add H4 check

* Add category in title check

* use array destructuring

* Add space check

scripts/lint-changelog.js

@@ -0,0 +1,131 @@
+"use strict";
+const fs = require("fs");
+const path = require("path");
+
+const CHANGELOG_DIR = "changelog_unreleased";
+const TEMPLATE_FILE = "TEMPLATE.md";
+const CHANGELOG_CATEGORIES = [
+  "angular",
+  "api",
+  "cli",
+  "css",
+  "flow",
+  "graphql",
+  "handlebars",
+  "html",
+  "javascript",
+  "json",
+  "less",
+  "lwc",
+  "markdown",
+  "mdx",
+  "scss",
+  "typescript",
+  "vue",
+  "yaml"
+];
+const CHANGELOG_ROOT = path.join(__dirname, `../${CHANGELOG_DIR}`);
+const showErrorMessage = message => {
+  console.error(message);
+  process.exitCode = 1;
+};
+
+const files = fs.readdirSync(CHANGELOG_ROOT);
+for (const file of files) {
+  if (file !== TEMPLATE_FILE && !CHANGELOG_CATEGORIES.includes(file)) {
+    showErrorMessage(`Please remove "${file}" from "${CHANGELOG_DIR}".`);
+  }
+}
+for (const file of [TEMPLATE_FILE, ...CHANGELOG_CATEGORIES]) {
+  if (!files.includes(file)) {
+    showErrorMessage(`Please don't remove "${file}" from "${CHANGELOG_DIR}".`);
+  }
+}
+
+const authorRegex = /by \[@(.*?)\]\(https:\/\/github\.com\/\1\)/;
+const titleRegex = /^#{4} (.*?)\(\[#\d{4,}]/;
+
+const template = fs.readFileSync(
+  path.join(CHANGELOG_ROOT, TEMPLATE_FILE),
+  "utf8"
+);
+const [templateComment] = template.match(/<!--[\s\S]*?-->/);
+const [templateAuthorLink] = template.match(authorRegex);
+
+for (const category of CHANGELOG_CATEGORIES) {
+  const files = fs.readdirSync(path.join(CHANGELOG_ROOT, category));
+  if (!files.includes(".gitkeep")) {
+    showErrorMessage(
+      `Please don't remove ".gitkeep" from "${CHANGELOG_DIR}/${category}".`
+    );
+  }
+
+  for (const prFile of files) {
+    if (prFile === ".gitkeep") {
+      continue;
+    }
+
+    const match = prFile.match(/^pr-(\d{4,})\.md$/);
+    const displayPath = `${CHANGELOG_DIR}/${category}/${prFile}`;
+
+    if (!match) {
+      showErrorMessage(
+        `[${displayPath}]: Filename is not in form of "pr-{PR_NUMBER}.md".`
+      );
+      continue;
+    }
+    const [, prNumber] = match;
+    const content = fs.readFileSync(
+      path.join(CHANGELOG_DIR, category, prFile),
+      "utf8"
+    );
+    const prLink = `[#${prNumber}](https://github.com/prettier/prettier/pull/${prNumber})`;
+
+    if (!content.includes(prLink)) {
+      showErrorMessage(`[${displayPath}]: PR link "${prLink}" is missing.`);
+    }
+    if (!authorRegex.test(content)) {
+      showErrorMessage(`[${displayPath}]: Author link is missing.`);
+    }
+    if (content.includes(templateComment)) {
+      showErrorMessage(
+        `[${displayPath}]: Please remove template comments at top.`
+      );
+    }
+    if (content.includes(templateAuthorLink)) {
+      showErrorMessage(
+        `[${displayPath}]: Please change author link to your github account.`
+      );
+    }
+    if (!content.startsWith("#### ")) {
+      showErrorMessage(`[${displayPath}]: Please use h4("####") for title.`);
+    }
+    const titleMatch = content.match(titleRegex);
+    if (!titleMatch) {
+      showErrorMessage(`[${displayPath}]: Something wrong in title.`);
+      continue;
+    }
+    const [, title] = titleMatch;
+    const categoryInTitle = title
+      .split(":")
+      .shift()
+      .trim();
+    if (CHANGELOG_CATEGORIES.includes(categoryInTitle.toLowerCase())) {
+      showErrorMessage(
+        `[${displayPath}]: Please remove "${categoryInTitle}:" in title.`
+      );
+    }
+
+    if (title.startsWith(" ")) {
+      showErrorMessage(
+        `[${displayPath}]: Don't add extra space(s) at beginning of title.`
+      );
+    }
+
+    if (!title.endsWith(" ") || title.length - title.trimEnd().length !== 1) {
+      showErrorMessage(
+        `[${displayPath}]: Please put one space between title and PR link.`
+      );
+    }
+  }
+}