Clone engine262 in /engine262

engine262/test/eslint-plugin-engine262/valid-throw.js

@@ -0,0 +1,63 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const acorn = require('acorn');
+
+function isThrowCall(node) {
+  return node.callee.type === 'MemberExpression'
+    && node.callee.computed === false
+    && node.callee.object.type === 'Identifier'
+    && node.callee.object.name === 'surroundingAgent'
+    && node.callee.property.type === 'Identifier'
+    && node.callee.property.name === 'Throw';
+}
+
+const templates = {};
+
+{
+  const source = fs.readFileSync(path.join(__dirname, '../../src/messages.mjs'), 'utf8');
+  const ast = acorn.parse(source, { ecmaVersion: 2020, sourceType: 'module' });
+
+  ast.body.forEach((n) => {
+    if (n.type !== 'ExportNamedDeclaration') {
+      return;
+    }
+    const [v] = n.declaration.declarations;
+    const name = v.id.name;
+    const length = v.init.params.length;
+    templates[name] = length;
+  });
+}
+
+module.exports = {
+  create(context) {
+    return {
+      CallExpression(node) {
+        if (!isThrowCall(node)) {
+          return;
+        }
+        if (node.arguments.length === 1 && node.arguments[0].type !== 'Literal') {
+          return;
+        }
+        const [type, template, ...templateArgs] = node.arguments;
+        if (!type || type.type !== 'Literal') {
+          context.report(node, 'Throw must use a valid error constructor');
+          return;
+        }
+        if (!template || template.type !== 'Literal') {
+          context.report(node, 'Throw must use a valid message template');
+          return;
+        }
+        const tfn = templates[template.value];
+        if (tfn === undefined) {
+          context.report(template, `'${template.value}' is not a valid message template`);
+          return;
+        }
+        if (tfn !== templateArgs.length) {
+          context.report(node, `Template expects ${tfn} args`);
+        }
+      },
+    };
+  },
+};