diff --git a/.gitignore b/.gitignore
index 5cab996..664c482 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,8 @@
 
 **/__pycache__/
 *.pyc
+**/*.egg-info/
+*.coverage
 
 *.sqlite3
 *.db
\ No newline at end of file
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
new file mode 100644
index 0000000..d783cc3
--- /dev/null
+++ b/.gitlab-ci.yml
@@ -0,0 +1,11 @@
+---
+image: debian:buster
+
+test:
+  script:
+  - apt-get update -qy
+  - apt-get install -y --no-install-recommends python3-dev python3-pip python3-coverage python3-setuptools build-essential
+  - pip3 install wheel
+  - pip3 install -r requirements.txt
+  - python3-coverage run --branch -m unittest discover matemat
+  - python3-coverage report -m
diff --git a/matemat/db/database.py b/matemat/db/database.py
index 1b49c76..c297721 100644
--- a/matemat/db/database.py
+++ b/matemat/db/database.py
@@ -1,3 +1,4 @@
+
 from typing import List, Optional
 
 import apsw
@@ -276,6 +277,8 @@ class Database(object):
         return Product(product_id, name, price_member, price_non_member)
 
     def change_product(self, product: Product):
+        if product.id == -1:
+            raise ValueError('Invalid product ID')
         with self.transaction() as c:
             c.execute('''
             UPDATE products
@@ -291,6 +294,8 @@ class Database(object):
             })
 
     def delete_product(self, product: Product):
+        if product.id == -1:
+            raise ValueError('Invalid product ID')
         with self.transaction() as c:
             c.execute('''
             DELETE FROM products
@@ -298,6 +303,8 @@ class Database(object):
             ''', [product.id])
 
     def increment_consumption(self, user: User, product: Product, count: int = 1):
+        if product.id == -1:
+            raise ValueError('Invalid product ID')
         with self.transaction() as c:
             c.execute('''
             SELECT count
@@ -342,6 +349,8 @@ class Database(object):
             })
 
     def restock(self, product: Product, count: int):
+        if product.id == -1:
+            raise ValueError('Invalid product ID')
         with self.transaction() as c:
             c.execute('''
             UPDATE products
diff --git a/matemat/db/test/test_database.py b/matemat/db/test/test_database.py
index 76f57c7..a03fbd4 100644
--- a/matemat/db/test/test_database.py
+++ b/matemat/db/test/test_database.py
@@ -49,11 +49,13 @@ class DatabaseTest(unittest.TestCase):
         """
         with self.db as db:
             with db.transaction() as c:
-                c.execute("INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, NULL)")
+                c.execute('''
+                INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42)
+                ''')
             c = db._sqlite_db.cursor()
             c.execute("SELECT * FROM users")
             user = c.fetchone()
-            self.assertEqual((1, 'testuser', None, 'supersecurepassword', None, 1, 1, 0, None), user)
+            self.assertEqual((1, 'testuser', None, 'supersecurepassword', None, 1, 1, 0, 42), user)
 
     def test_transaction_rollback(self):
         """
@@ -63,7 +65,7 @@ class DatabaseTest(unittest.TestCase):
             try:
                 with db.transaction() as c:
                     c.execute("""
-                      INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, NULL)
+                      INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42)
                     """)
                     raise ValueError('This should trigger a rollback')
             except ValueError as e:
diff --git a/matemat/primitives/Product.py b/matemat/primitives/Product.py
index 72aaa1a..f3d1674 100644
--- a/matemat/primitives/Product.py
+++ b/matemat/primitives/Product.py
@@ -6,8 +6,6 @@ class Product(object):
                  name: str,
                  price_member: int,
                  price_non_member: int):
-        if product_id == -1:
-            raise ValueError('Invalid product ID')
         self._product_id: int = product_id
         self._name: str = name
         self._price_member: int = price_member
diff --git a/setup.py b/setup.py
index 034a818..0fc605f 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@ from setuptools import setup
 
 setup(
     name='matemat',
-    version='2.00',
+    version='2.0',
     packages=['matemat'],
     url='',
     license='',