tools: add eslint rule for documented errors

PR-URL: https://github.com/nodejs/node/pull/16450
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/tools/eslint-rules/documented-errors.js b/tools/eslint-rules/documented-errors.js
new file mode 100644
index 0000000000..471452d67a
--- /dev/null
+++ b/tools/eslint-rules/documented-errors.js
@@ -0,0 +1,46 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+const doc = fs.readFileSync(path.resolve(__dirname, '../../doc/api/errors.md'),
+                            'utf8');
+
+function isInDoc(code) {
+  return doc.match(`### ${code}`) != null;
+}
+
+function includesAnchor(code) {
+  return doc.match(`<a id="${code}"></a>`) != null;
+}
+
+function errorForNode(node) {
+  return node.expression.arguments[0].value;
+}
+
+function isDefiningError(node) {
+  return node.expression &&
+         node.expression.type === 'CallExpression' &&
+         node.expression.callee &&
+         node.expression.callee.name === 'E';
+}
+
+module.exports = {
+  create: function(context) {
+    return {
+      ExpressionStatement: function(node) {
+        if (!isDefiningError(node)) return;
+        const code = errorForNode(node);
+        if (!isInDoc(code)) {
+          const message = `"${code}" is not documented in doc/api/errors.md`;
+          context.report({ node, message });
+        }
+        if (!includesAnchor(code)) {
+          const message =
+            `doc/api/errors.md does not have an anchor for "${code}"`;
+          context.report({ node, message });
+        }
+      }
+    };
+  }
+};