feat: implement graceful shutdown handling

src/lib/db.test.ts

@@ -0,0 +1,56 @@
+import { describe, it, expect, mock, beforeEach } from "bun:test";
+
+// Mock shutdown module before importing db
+mock.module("./shutdown", () => {
+    let shuttingDown = false;
+    let transactions = 0;
+    return {
+        isShuttingDown: () => shuttingDown,
+        setShuttingDown: (v: boolean) => { shuttingDown = v; },
+        incrementTransactions: () => { transactions++; },
+        decrementTransactions: () => { transactions--; },
+        getActiveTransactions: () => transactions,
+    };
+});
+
+// Mock DrizzleClient
+mock.module("./DrizzleClient", () => ({
+    DrizzleClient: {
+        transaction: async (cb: any) => cb("MOCK_TX")
+    }
+}));
+
+import { withTransaction } from "./db";
+import { setShuttingDown, getActiveTransactions } from "./shutdown";
+
+describe("db withTransaction", () => {
+    beforeEach(() => {
+        setShuttingDown(false);
+    });
+
+    it("should allow transactions when not shutting down", async () => {
+        const result = await withTransaction(async (tx) => {
+            return "success";
+        });
+        expect(result).toBe("success");
+        expect(getActiveTransactions()).toBe(0);
+    });
+
+    it("should throw error when shutting down", async () => {
+        setShuttingDown(true);
+        expect(withTransaction(async (tx) => {
+            return "success";
+        })).rejects.toThrow("System is shutting down, no new transactions allowed.");
+        expect(getActiveTransactions()).toBe(0);
+    });
+
+    it("should increment and decrement transaction count", async () => {
+        let countDuring = 0;
+        await withTransaction(async (tx) => {
+            countDuring = getActiveTransactions();
+            return "ok";
+        });
+        expect(countDuring).toBe(1);
+        expect(getActiveTransactions()).toBe(0);
+    });
+});