Only initialize IDBShim and database once

src/mlpccg/database.ts

@@ -20,8 +20,10 @@ class CardDatabase extends Dexie {
 export let Database: CardDatabase | null = null;
 
 export function initDB() {
+  if (Database == null) {
     Database = new CardDatabase();
   }
+}
 
 export async function getCards(filter: CardFilter) {
   if (Database == null) {

src/testing/IDBShim.ts

@@ -0,0 +1,11 @@
+import Dexie from "dexie";
+
+let init = false;
+
+export function setupIDBShim() {
+  if (!init) {
+    const setGlobalVars = require("indexeddbshim");
+    setGlobalVars(Dexie.dependencies);
+    init = true;
+  }
+}

src/tests/unit/database.spec.ts

@@ -1,7 +1,7 @@
 import { loadSets, getCards, Database, initDB, cardFullName } from "@/mlpccg";
-import Dexie from "dexie";
-const setGlobalVars = require("indexeddbshim");
-setGlobalVars(Dexie.dependencies);
+import { setupIDBShim } from "@/testing/IDBShim";
+
+setupIDBShim();
 
 describe("mlpccg/Database", () => {
   beforeAll(async () => {