splitting unit + integration testing apart attempt #1

src/services/db/connection.ts

@@ -2,13 +2,6 @@
 import { Pool, PoolConfig } from 'pg';
 import { logger } from '../logger';
 
-// This is the singleton instance. It's defined at the module level.
-// When Node.js caches this module, every `import` of this file across the
-// entire application (including in different test files and the running server)
-// will share this exact same `poolInstance` variable. This is the key to
-// making the singleton pattern work reliably for our tests.
-
-// Extend the Pool type to hold our custom ID for logging.
 interface TrackedPool extends Pool {
   poolId?: string;
 }
@@ -42,19 +35,17 @@ const createPool = (): Pool => {
   console.log(`[DEBUG] connection.ts: typeof Pool is "${typeof Pool}"`);
   if (typeof Pool !== 'function') {
     console.error('[DEBUG] CRITICAL: Pool is NOT a function/class!', Pool);
-  } else {
-    try {
-      // Check if it's a valid constructor by checking prototype or string representation
-      console.log('[DEBUG] connection.ts: Pool string repr:', Pool.toString().substring(0, 50));
-    } catch (e) {
-      console.log('[DEBUG] connection.ts: Could not stringify Pool');
-    }
   }
   // -----------------------------
 
   try {
     const newPool: TrackedPool = new Pool(poolConfig);
     newPool.poolId = poolId;
+    
+    // --- ADDED SUCCESS LOG ---
+    console.log('[DEBUG] connection.ts: Successfully instantiated Pool.');
+    // -------------------------
+    
     return newPool;
   } catch (error) {
     console.error('[DEBUG] connection.ts: "new Pool()" threw error:', error);
@@ -69,10 +60,10 @@ const createPool = (): Pool => {
 export const getPool = (): Pool => {    
     // This function acts as a singleton accessor for the database pool.
     if (!poolInstance) {
-        console.log('[DB POOL] Creating NEW pool instance.'); // DIAGNOSTIC LOGGING #2
+        console.log('[DB POOL] Creating NEW pool instance.');
         poolInstance = createPool();
     } else {
-        console.log(`[DB POOL] Returning EXISTING pool instance. ID: ${poolInstance.poolId}`); // DIAGNOSTIC LOGGING #2
+        console.log(`[DB POOL] Returning EXISTING pool instance. ID: ${poolInstance.poolId}`);
     }
     return poolInstance;
 };

src/tests/setup/mock-db.ts

@@ -24,8 +24,12 @@ export const mockPoolInstance = {
   waitingCount: 0,
 };
 
-// Define the mock constructor that returns our stable instance.
+// FIX: Use a standard function for the constructor.
-export const MockPool = vi.fn(() => mockPoolInstance);
+// An arrow function `() => {}` cannot be called with `new`, which was causing the
+// "is not a constructor" TypeError across all database tests.
+export const MockPool = vi.fn(function() {
+  return mockPoolInstance;
+});
 
 // This is the actual mock factory function for vi.mock.
 export const pgMockFactory = () => ({

src/tests/setup/unit-setup.ts

@@ -56,7 +56,7 @@ afterEach(cleanup);
 // 1. Define the mock pool instance and constructor *outside* vi.mock first
 // We use vi.hoisted to ensure these variables are available to the mock factory
 const { mockPoolInstance, MockPool } = vi.hoisted(() => {
-  console.log('[DEBUG] unit-setup.ts: Initializing hoisted mock variables'); // ADD THIS
+  console.log('[DEBUG] unit-setup.ts: Initializing hoisted mock variables');
   const mockQuery = vi.fn().mockResolvedValue({ rows: [], rowCount: 0 });
   const mockRelease = vi.fn();
   const mockConnect = vi.fn().mockResolvedValue({
@@ -75,10 +75,12 @@ const { mockPoolInstance, MockPool } = vi.hoisted(() => {
   };
 
   // The constructor function
-  const Constructor = vi.fn(() => {
+  // FIX: Use a standard function so 'new' works, and log success
-    console.log('[DEBUG] unit-setup.ts: MockPool constructor called!'); // ADD THIS
+  const Constructor = vi.fn(function() {
+    console.log('[DEBUG] unit-setup.ts: MockPool constructor called successfully via "new"!');
     return instance;
   });
+
   return { mockPoolInstance: instance, MockPool: Constructor };
 });
 
@@ -87,7 +89,7 @@ const { mockPoolInstance, MockPool } = vi.hoisted(() => {
  */
 // 2. Mock 'pg' using the hoisted variables
 vi.mock('pg', () => {
-  console.log('[DEBUG] unit-setup.ts: vi.mock("pg") factory executing'); // ADD THIS
+  console.log('[DEBUG] unit-setup.ts: vi.mock("pg") factory executing');
   return {
     // Named export must be the constructor
     Pool: MockPool,