add support for different recommendation levels: strict and standard

tests/unit/domain/RecommendationLevel.ts

@@ -0,0 +1,17 @@
+import 'mocha';
+import { expect } from 'chai';
+import { RecommendationLevelNames, RecommendationLevel } from '@/domain/RecommendationLevel';
+
+describe('RecommendationLevel', () => {
+    describe('RecommendationLevelNames', () => {
+        // arrange
+        const expected = [
+            RecommendationLevel[RecommendationLevel.Strict],
+            RecommendationLevel[RecommendationLevel.Standard],
+        ];
+        // act
+        const actual = RecommendationLevelNames;
+        // assert
+        expect(actual).to.have.deep.members(expected);
+    });
+});