diff --git a/middleware/auth.py b/middleware/auth.py
index 5f85c13e..5b4589b7 100644
--- a/middleware/auth.py
+++ b/middleware/auth.py
@@ -100,7 +100,7 @@ class AuthManager:
             if exp is None:
                 raise InvalidTokenException("Token missing expiration")
 
-            if datetime.now(timezone.utc) > datetime.fromtimestamp(exp):
+            if datetime.now(timezone.utc) > datetime.fromtimestamp(exp, tz=timezone.utc):
                 raise TokenExpiredException()
 
             # Extract user data
diff --git a/tests/integration/api/v1/test_export.py b/tests/integration/api/v1/test_product_export.py
similarity index 100%
rename from tests/integration/api/v1/test_export.py
rename to tests/integration/api/v1/test_product_export.py
diff --git a/tests/unit/services/test_product_service.py b/tests/unit/services/test_product_service.py
index d94a755d..72f1b8dc 100644
--- a/tests/unit/services/test_product_service.py
+++ b/tests/unit/services/test_product_service.py
@@ -2,7 +2,14 @@
 import pytest
 
 from app.services.product_service import ProductService
-from models.schemas.product import ProductCreate
+from app.exceptions import (
+    ProductNotFoundException,
+    ProductAlreadyExistsException,
+    InvalidProductDataException,
+    ProductValidationException,
+    ValidationException,
+)
+from models.schemas.product import ProductCreate, ProductUpdate
 from models.database.product import Product
 
 
@@ -12,8 +19,8 @@ class TestProductService:
     def setup_method(self):
         self.service = ProductService()
 
-    def test_create_product_with_gtin_validation(self, db):
-        """Test product creation with GTIN validation"""
+    def test_create_product_success(self, db):
+        """Test successful product creation with valid data"""
         product_data = ProductCreate(
             product_id="SVC001",
             title="Service Test Product",
@@ -25,11 +32,13 @@ class TestProductService:
         product = self.service.create_product(db, product_data)
 
         assert product.product_id == "SVC001"
+        assert product.title == "Service Test Product"
         assert product.gtin == "1234567890123"
         assert product.marketplace == "TestMarket"
+        assert product.price == "19.99"  # Price is stored as string after processing
 
     def test_create_product_invalid_gtin(self, db):
-        """Test product creation with invalid GTIN"""
+        """Test product creation with invalid GTIN raises InvalidProductDataException"""
         product_data = ProductCreate(
             product_id="SVC002",
             title="Service Test Product",
@@ -37,22 +46,238 @@ class TestProductService:
             price="19.99",
         )
 
-        with pytest.raises(ValueError, match="Invalid GTIN format"):
+        with pytest.raises(InvalidProductDataException) as exc_info:
             self.service.create_product(db, product_data)
 
-    def test_get_products_with_filters(self, db, test_product):
+        assert exc_info.value.error_code == "INVALID_PRODUCT_DATA"
+        assert "Invalid GTIN format" in str(exc_info.value)
+        assert exc_info.value.status_code == 422
+        assert exc_info.value.details.get("field") == "gtin"
+
+    def test_create_product_missing_product_id(self, db):
+        """Test product creation without product_id raises ProductValidationException"""
+        product_data = ProductCreate(
+            product_id="",  # Empty product ID
+            title="Service Test Product",
+            price="19.99",
+        )
+
+        with pytest.raises(ProductValidationException) as exc_info:
+            self.service.create_product(db, product_data)
+
+        assert exc_info.value.error_code == "PRODUCT_VALIDATION_FAILED"
+        assert "Product ID is required" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "product_id"
+
+    def test_create_product_missing_title(self, db):
+        """Test product creation without title raises ProductValidationException"""
+        product_data = ProductCreate(
+            product_id="SVC003",
+            title="",  # Empty title
+            price="19.99",
+        )
+
+        with pytest.raises(ProductValidationException) as exc_info:
+            self.service.create_product(db, product_data)
+
+        assert exc_info.value.error_code == "PRODUCT_VALIDATION_FAILED"
+        assert "Product title is required" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "title"
+
+    def test_create_product_already_exists(self, db, test_product):
+        """Test creating product with existing ID raises ProductAlreadyExistsException"""
+        product_data = ProductCreate(
+            product_id=test_product.product_id,  # Use existing product ID
+            title="Duplicate Product",
+            price="29.99",
+        )
+
+        with pytest.raises(ProductAlreadyExistsException) as exc_info:
+            self.service.create_product(db, product_data)
+
+        assert exc_info.value.error_code == "PRODUCT_ALREADY_EXISTS"
+        assert test_product.product_id in str(exc_info.value)
+        assert exc_info.value.status_code == 409
+        assert exc_info.value.details.get("product_id") == test_product.product_id
+
+    def test_create_product_invalid_price(self, db):
+        """Test product creation with invalid price raises InvalidProductDataException"""
+        product_data = ProductCreate(
+            product_id="SVC004",
+            title="Service Test Product",
+            price="invalid_price",
+        )
+
+        with pytest.raises(InvalidProductDataException) as exc_info:
+            self.service.create_product(db, product_data)
+
+        assert exc_info.value.error_code == "INVALID_PRODUCT_DATA"
+        assert "Invalid price format" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "price"
+
+    def test_get_product_by_id_or_raise_success(self, db, test_product):
+        """Test successful product retrieval by ID"""
+        product = self.service.get_product_by_id_or_raise(db, test_product.product_id)
+
+        assert product.product_id == test_product.product_id
+        assert product.title == test_product.title
+
+    def test_get_product_by_id_or_raise_not_found(self, db):
+        """Test product retrieval with non-existent ID raises ProductNotFoundException"""
+        with pytest.raises(ProductNotFoundException) as exc_info:
+            self.service.get_product_by_id_or_raise(db, "NONEXISTENT")
+
+        assert exc_info.value.error_code == "PRODUCT_NOT_FOUND"
+        assert "NONEXISTENT" in str(exc_info.value)
+        assert exc_info.value.status_code == 404
+        assert exc_info.value.details.get("resource_type") == "Product"
+        assert exc_info.value.details.get("identifier") == "NONEXISTENT"
+
+    def test_get_products_with_filters_success(self, db, test_product):
         """Test getting products with various filters"""
-        products, total = self.service.get_products_with_filters(db, brand="TestBrand")
-
-        assert total == 1
-        assert len(products) == 1
-        assert products[0].brand == "TestBrand"
-
-    def test_get_products_with_search(self, db, test_product):
-        """Test getting products with search"""
         products, total = self.service.get_products_with_filters(
-            db, search="Test Product"
+            db, brand=test_product.brand
         )
 
         assert total == 1
         assert len(products) == 1
+        assert products[0].brand == test_product.brand
+
+    def test_get_products_with_search(self, db, test_product):
+        """Test getting products with search term"""
+        products, total = self.service.get_products_with_filters(
+            db, search="Test Product"
+        )
+
+        assert total >= 1
+        assert len(products) >= 1
+        # Verify search worked by checking that title contains search term
+        found_product = next((p for p in products if p.product_id == test_product.product_id), None)
+        assert found_product is not None
+
+    def test_update_product_success(self, db, test_product):
+        """Test successful product update"""
+        update_data = ProductUpdate(
+            title="Updated Product Title",
+            price="39.99"
+        )
+
+        updated_product = self.service.update_product(db, test_product.product_id, update_data)
+
+        assert updated_product.title == "Updated Product Title"
+        assert updated_product.price == "39.99"  # Price is stored as string after processing
+        assert updated_product.product_id == test_product.product_id  # ID unchanged
+
+    def test_update_product_not_found(self, db):
+        """Test updating non-existent product raises ProductNotFoundException"""
+        update_data = ProductUpdate(title="Updated Title")
+
+        with pytest.raises(ProductNotFoundException) as exc_info:
+            self.service.update_product(db, "NONEXISTENT", update_data)
+
+        assert exc_info.value.error_code == "PRODUCT_NOT_FOUND"
+        assert "NONEXISTENT" in str(exc_info.value)
+
+    def test_update_product_invalid_gtin(self, db, test_product):
+        """Test updating product with invalid GTIN raises InvalidProductDataException"""
+        update_data = ProductUpdate(gtin="invalid_gtin")
+
+        with pytest.raises(InvalidProductDataException) as exc_info:
+            self.service.update_product(db, test_product.product_id, update_data)
+
+        assert exc_info.value.error_code == "INVALID_PRODUCT_DATA"
+        assert "Invalid GTIN format" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "gtin"
+
+    def test_update_product_empty_title(self, db, test_product):
+        """Test updating product with empty title raises ProductValidationException"""
+        update_data = ProductUpdate(title="")
+
+        with pytest.raises(ProductValidationException) as exc_info:
+            self.service.update_product(db, test_product.product_id, update_data)
+
+        assert exc_info.value.error_code == "PRODUCT_VALIDATION_FAILED"
+        assert "Product title cannot be empty" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "title"
+
+    def test_update_product_invalid_price(self, db, test_product):
+        """Test updating product with invalid price raises InvalidProductDataException"""
+        update_data = ProductUpdate(price="invalid_price")
+
+        with pytest.raises(InvalidProductDataException) as exc_info:
+            self.service.update_product(db, test_product.product_id, update_data)
+
+        assert exc_info.value.error_code == "INVALID_PRODUCT_DATA"
+        assert "Invalid price format" in str(exc_info.value)
+        assert exc_info.value.details.get("field") == "price"
+
+    def test_delete_product_success(self, db, test_product):
+        """Test successful product deletion"""
+        result = self.service.delete_product(db, test_product.product_id)
+
+        assert result is True
+
+        # Verify product is deleted
+        deleted_product = self.service.get_product_by_id(db, test_product.product_id)
+        assert deleted_product is None
+
+    def test_delete_product_not_found(self, db):
+        """Test deleting non-existent product raises ProductNotFoundException"""
+        with pytest.raises(ProductNotFoundException) as exc_info:
+            self.service.delete_product(db, "NONEXISTENT")
+
+        assert exc_info.value.error_code == "PRODUCT_NOT_FOUND"
+        assert "NONEXISTENT" in str(exc_info.value)
+
+    def test_get_stock_info_success(self, db, test_product_with_stock):
+        """Test getting stock info for product with stock"""
+        stock_info = self.service.get_stock_info(db, test_product_with_stock.gtin)
+
+        assert stock_info is not None
+        assert stock_info.gtin == test_product_with_stock.gtin
+        assert stock_info.total_quantity > 0
+        assert len(stock_info.locations) > 0
+
+    def test_get_stock_info_no_stock(self, db, test_product):
+        """Test getting stock info for product without stock"""
+        stock_info = self.service.get_stock_info(db, test_product.gtin or "1234567890123")
+
+        assert stock_info is None
+
+    def test_product_exists_true(self, db, test_product):
+        """Test product_exists returns True for existing product"""
+        exists = self.service.product_exists(db, test_product.product_id)
+        assert exists is True
+
+    def test_product_exists_false(self, db):
+        """Test product_exists returns False for non-existent product"""
+        exists = self.service.product_exists(db, "NONEXISTENT")
+        assert exists is False
+
+    def test_generate_csv_export_success(self, db, test_product):
+        """Test CSV export generation"""
+        csv_generator = self.service.generate_csv_export(db)
+
+        # Convert generator to list to test content
+        csv_lines = list(csv_generator)
+
+        assert len(csv_lines) > 1  # Header + at least one data row
+        assert csv_lines[0].startswith("product_id,title,description")  # Check header
+
+        # Check that test product appears in CSV
+        csv_content = "".join(csv_lines)
+        assert test_product.product_id in csv_content
+
+    def test_generate_csv_export_with_filters(self, db, test_product):
+        """Test CSV export with marketplace filter"""
+        csv_generator = self.service.generate_csv_export(
+            db,
+            marketplace=test_product.marketplace
+        )
+
+        csv_lines = list(csv_generator)
+        assert len(csv_lines) >= 1  # At least header
+
+        if len(csv_lines) > 1:  # If there's data
+            csv_content = "".join(csv_lines)
+            assert test_product.marketplace in csv_content