Refactor by comments

Author: LijieZhang1998

snippets/mongocompat/mongotypes.js

@@ -629,24 +629,33 @@ if (typeof (DBRef) != "undefined") {
     };
 
     DBRef.prototype.toString = function() {
-        return `DBRef("${this.collection}", ${this.oid.tojson()}` +
+        return `DBRef("${this.collection}", ${tojson(this.oid)}` +
             (this.db ? `, "${this.db}"` : "") + ")";
     };
 
     Object.defineProperty(DBRef.prototype, "$ref", {
         get: function () {
             return this.collection;
         },
+        set: function (value) {
+            this.collection = value;
+        },
     });
     Object.defineProperty(DBRef.prototype, "$id", {
         get: function () {
             return this.oid;
         },
+        set: function (value) {
+            this.oid = value;
+        },
     });
     Object.defineProperty(DBRef.prototype, "$db", {
         get: function () {
             return this.db;
         },
+        set: function (value) {
+            this.db = value;
+        },
     });
 } else {
     print("warning: no DBRef");

snippets/mongocompat/test.js

@@ -81,3 +81,19 @@ assert.strictEqual(dbRef.$db, 'testDb');
 const dbRefNoDb = DBRef('testColl', id);
 assert.strictEqual(dbRefNoDb.toString(), 'DBRef("testColl", ObjectId("68ffa28b77bba38c9ddcf376"))');
 assert.strictEqual(dbRefNoDb.$db, undefined);
+const dbRefStringId = DBRef('testColl', '68ffa28b77bba38c9ddcf376');
+assert.strictEqual(dbRefStringId.toString(), 'DBRef("testColl", "68ffa28b77bba38c9ddcf376")');
+const dbRefForSetters = DBRef('originalColl', id, 'originalDb');
+dbRefForSetters.$ref = 'newColl';
+assert.strictEqual(dbRefForSetters.$ref, 'newColl');
+assert.strictEqual(dbRefForSetters.collection, 'newColl');
+assert.strictEqual(dbRefForSetters.toString(), 'DBRef("newColl", ObjectId("68ffa28b77bba38c9ddcf376"), "originalDb")');
+const newId = ObjectId('507f1f77bcf86cd799439011');
+dbRefForSetters.$id = newId;
+assert.strictEqual(dbRefForSetters.$id, newId);
+assert.strictEqual(dbRefForSetters.oid, newId);
+assert.strictEqual(dbRefForSetters.toString(), 'DBRef("newColl", ObjectId("507f1f77bcf86cd799439011"), "originalDb")');
+dbRefForSetters.$db = 'newDb';
+assert.strictEqual(dbRefForSetters.$db, 'newDb');
+assert.strictEqual(dbRefForSetters.db, 'newDb');
+assert.strictEqual(dbRefForSetters.toString(), 'DBRef("newColl", ObjectId("507f1f77bcf86cd799439011"), "newDb")');