docs/verify-links: update to disallow path-absolute doc links

docs/verify-links.js

@@ -42,14 +42,25 @@ async function verifyUrl(basePath, url) {
   }
 
   // Only verify existence of local files for now, so skip anything with a schema
-  if (!url.match(/[a-z]+:/)) {
-    const path = url.startsWith('/')
-      ? resolvePath(projectRoot, `.${url}`)
-      : resolvePath(dirname(resolvePath(projectRoot, basePath)), url);
-    const exists = await fs.pathExists(path);
-    if (!exists) {
-      return { url, basePath, problem: 'missing' };
+  if (url.match(/[a-z]+:/)) {
+    return;
+  }
+
+  let path = '';
+
+  if (url.startsWith('/')) {
+    if (url.startsWith('/docs/') && basePath.match(/^(?:docs|microsite)\//)) {
+      return { url, basePath, problem: 'not-relative' };
     }
+
+    path = resolvePath(projectRoot, `.${url}`);
+  } else {
+    path = resolvePath(dirname(resolvePath(projectRoot, basePath)), url);
+  }
+
+  const exists = await fs.pathExists(path);
+  if (!exists) {
+    return { url, basePath, problem: 'missing' };
   }
 
   return;
@@ -93,6 +104,10 @@ async function main() {
     for (const { url, basePath, problem } of badUrls) {
       if (problem === 'missing') {
         console.error(`Unable to reach ${url}, linked from ${basePath}`);
+      } else if (problem === 'not-relative') {
+        console.error('Links to /docs/ must be relative');
+        console.error(`  From: ${basePath}`);
+        console.error(`  To: ${url}`);
       } else if (problem === 'absolute') {
         console.error(`Link to docs/ should be replaced by a relative URL`);
         console.error(`  From: ${basePath}`);