test: provide better message for orphan output documentation

PR-URL: #21913
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/doctool/test-make-doc.js

@@ -12,6 +12,8 @@ const fs = require('fs');
 const path = require('path');
 
 const apiPath = path.resolve(__dirname, '..', '..', 'out', 'doc', 'api');
+const mdPath = path.resolve(__dirname, '..', '..', 'doc', 'api');
+const allMD = fs.readdirSync(mdPath);
 const allDocs = fs.readdirSync(apiPath);
 assert.ok(allDocs.includes('index.html'));
 
@@ -22,6 +24,15 @@ const actualDocs = allDocs.filter(
   }
 );
 
+for (const name of actualDocs) {
+  if (name.startsWith('all.')) continue;
+
+  assert.ok(
+    allMD.includes(name.replace(/\.\w+$/, '.md')),
+    `Unexpected output: out/doc/api/${name}, remove and rerun.`
+  );
+}
+
 const toc = fs.readFileSync(path.resolve(apiPath, 'index.html'), 'utf8');
 const re = /href="([^/]+\.html)"/;
 const globalRe = new RegExp(re, 'g');
@@ -43,7 +54,7 @@ for (const expectedDoc of expectedDocs) {
 // and that they are not empty files.
 for (const actualDoc of actualDocs) {
   assert.ok(
-    expectedDocs.includes(actualDoc), `${actualDoc} does not not match TOC`);
+    expectedDocs.includes(actualDoc), `${actualDoc} does not match TOC`);
 
   assert.ok(
     fs.statSync(path.join(apiPath, actualDoc)).size !== 0,