test: add some missing unit tests for 'convertObject' (eggjs#5303)

According to AI's suggestions at eggjs#5302,
it seems there're some missing unit tests and here's the fix for it.

test/lib/core/utils.test.js

@@ -125,6 +125,35 @@ describe('test/lib/core/utils.test.js', () => {
       assert(obj.undefined$ === undefined);
       assert(obj.boolean$ === '<Boolean>');
       assert(obj.symbol$ === '<Symbol>');
+      assert(obj.regexp$ === '<RegExp>');
+    });
+
+    it('should convert a plain recursive object', () => {
+      const obj = {
+        plainObj: 'Plain',
+        Id: 1,
+        recurisiveObj: {
+          value1: 'string',
+          value2: 1,
+          ignoreValue: /^[a-z]/,
+        },
+      };
+      utils.convertObject(obj, [ 'ignoreValue' ]);
+      assert(obj.recurisiveObj.value1 === 'string');
+      assert(obj.recurisiveObj.value2 === 1);
+      assert(obj.recurisiveObj.ignoreValue === '<RegExp>');
+      assert(obj.plainObj === 'Plain');
+      assert(obj.Id === 1);
+    });
+
+    it('should convert an anonymous class', () => {
+      const obj = {
+        anonymousClassWithPropName: class { },
+        '': class { },
+      };
+      utils.convertObject(obj);
+      assert(obj.anonymousClassWithPropName === '<Class anonymousClassWithPropName>');
+      assert(obj[''] === '<Class anonymous>');
     });
   });