added full api

backend/src/test/mockDb.ts

@@ -0,0 +1,52 @@
+import { afterEach } from 'node:test';
+
+import { db } from '../db/client.js';
+
+type QueryCall = {
+  text: string;
+  params: unknown[] | undefined;
+};
+
+type MockQueryResult = {
+  rowCount?: number;
+  rows?: unknown[];
+};
+
+type MockHandler = MockQueryResult | ((call: QueryCall) => MockQueryResult | Promise<MockQueryResult>);
+
+const originalQuery = db.query.bind(db);
+
+export const mockDb = (...handlers: MockHandler[]) => {
+  const calls: QueryCall[] = [];
+  const queue = [...handlers];
+
+  const mockedQuery = async (text: string, params?: unknown[]) => {
+    const call = { text, params };
+    calls.push(call);
+
+    const next = queue.shift();
+
+    if (!next) {
+      throw new Error(`Unexpected query: ${text}`);
+    }
+
+    const result = typeof next === 'function' ? await next(call) : next;
+
+    return {
+      rowCount: result.rowCount ?? result.rows?.length ?? 0,
+      rows: result.rows ?? [],
+    };
+  };
+
+  (db as typeof db & {
+    query: typeof db.query;
+  }).query = mockedQuery as typeof db.query;
+
+  return { calls };
+};
+
+afterEach(() => {
+  (db as typeof db & {
+    query: typeof originalQuery;
+  }).query = originalQuery;
+});