feat(challenge26): forbidden enum rule

tools/eslint-rules/rules/forbidden-enum.spec.ts

@@ -0,0 +1,11 @@
+import { TSESLint } from '@typescript-eslint/utils';
+import { rule, RULE_NAME } from './forbidden-enum';
+
+const ruleTester = new TSESLint.RuleTester({
+  parser: require.resolve('@typescript-eslint/parser'),
+});
+
+ruleTester.run(RULE_NAME, rule, {
+  valid: [`const example = true;`],
+  invalid: [],
+});