fix db connection closing in tests

src/server/db.js

@@ -1,14 +1,21 @@
 const mysql = require("mysql2/promise");
 
+let globalDb;
+
 async function connectToDb() {
-  const db = await mysql.createConnection({
+  if (globalDb) {
+    return globalDb;
+  }
+
+  globalDb = await mysql.createPool({
+    connectionLimit: 5,
     host: "impress.openneo.net",
     user: process.env["IMPRESS_MYSQL_USER"],
     password: process.env["IMPRESS_MYSQL_PASSWORD"],
     database: "openneo_impress",
   });
 
-  return db;
+  return globalDb;
 }
 
 module.exports = connectToDb;

src/server/index.test.js

@@ -12,15 +12,18 @@ const { query } = createTestClient(new ApolloServer(config));
 // keep an eye on perf - watch for tests with way too many queries!
 jest.mock("./db");
 let queryFn;
+let db;
 beforeEach(() => {
   connectToDb.mockImplementation(async (...args) => {
-    const db = await actualConnectToDb(...args);
+    db = await actualConnectToDb(...args);
     queryFn = jest.spyOn(db, "execute");
     return db;
   });
 });
 afterEach(() => {
   jest.resetAllMocks();
+  db.end();
+  db = null;
 });
 
 it("can load items", async () => {