diff --git a/packages/hydrooj/src/service/__mocks__/db.ts b/packages/hydrooj/src/service/__mocks__/db.ts
index 123ca6e57..53393b4f9 100644
--- a/packages/hydrooj/src/service/__mocks__/db.ts
+++ b/packages/hydrooj/src/service/__mocks__/db.ts
@@ -4,6 +4,8 @@ import mongodb, { Db, MongoClient } from 'mongodb';
 
 export let db: Db = null;
 export let client: MongoClient = null;
+export let db2: Db = null;
+export let client2: MongoClient = null;
 
 export const bus = new EventEmitter();
 
@@ -15,7 +17,16 @@ mongodb.MongoClient.connect(
     // @ts-ignore
     db = c.db(global.__MONGO_DB_NAME__);
     client = c;
-    bus.emit('connect');
+    mongodb.MongoClient.connect(
+        // @ts-ignore
+        global.__MONGO_URI__,
+        { useNewUrlParser: true, useUnifiedTopology: true },
+    ).then((c2) => {
+        // @ts-ignore
+        db2 = c2.db(global.__MONGO_DB_NAME__);
+        client2 = c2;
+        bus.emit('connect');
+    });
 });
 
 export function collection(c: string) {
@@ -26,6 +37,14 @@ export function getClient() {
     return client;
 }
 
+export function getClient2() {
+    return client2;
+}
+
 export function getDb() {
     return db;
 }
+
+export function getDb2() {
+    return db2;
+}
diff --git a/packages/hydrooj/test/db.ts b/packages/hydrooj/test/db.ts
index 708a5a3e5..4cc20d434 100644
--- a/packages/hydrooj/test/db.ts
+++ b/packages/hydrooj/test/db.ts
@@ -14,5 +14,7 @@ export async function connect() {
 export async function dispose() {
     const db = require('hydrooj/src/service/db');
     await db.getClient().close();
+    await db.getClient2().close();
     await db.getDb().close();
+    await db.getDb2().close();
 }