diff --git a/server/middleware/auth.js b/server/middleware/auth.js
index aced91c..6eaba58 100644
--- a/server/middleware/auth.js
+++ b/server/middleware/auth.js
@@ -1,5 +1,17 @@
 const jwt = require('jsonwebtoken');
-const { User, Tenant } = require('../models');
+
+// Allow models to be injected for testing
+let models = null;
+try {
+  models = require('../models');
+} catch (error) {
+  // Models will be injected during testing
+}
+
+// Function to set models (used in testing)
+function setModels(testModels) {
+  models = testModels;
+}
 
 async function authenticateToken(req, res, next) {
   const authHeader = req.headers['authorization'];
@@ -27,10 +39,10 @@ async function authenticateToken(req, res, next) {
     // For older tokens without tenantId, we need to look up the user's tenant
     let tenantId = decoded.tenantId;
     
-    const user = await User.findByPk(decoded.userId, {
+    const user = await models.User.findByPk(decoded.userId, {
       attributes: ['id', 'username', 'email', 'role', 'is_active', 'tenant_id'],
       include: [{
-        model: Tenant,
+        model: models.Tenant,
         as: 'tenant',
         attributes: ['slug', 'name']
       }]
@@ -89,5 +101,6 @@ function requireRole(roles) {
 
 module.exports = {
   authenticateToken,
-  requireRole
+  requireRole,
+  setModels
 };
diff --git a/server/tests/setup.js b/server/tests/setup.js
index 148bb75..67259f8 100644
--- a/server/tests/setup.js
+++ b/server/tests/setup.js
@@ -83,9 +83,9 @@ async function setupTestEnvironment() {
     id: mainModelsPath
   };
   
-  // Clear cache for middleware modules so they re-import the overridden models
-  const authMiddlewarePath = path.resolve(__dirname, '../middleware/auth.js');
-  delete require.cache[authMiddlewarePath];
+  // Inject test models into middleware modules
+  const authMiddleware = require('../middleware/auth');
+  authMiddleware.setModels(models);
   
   // Sync database
   await sequelize.sync({ force: true });