diff --git a/matemat/db/test/test_wrapper.py b/matemat/db/test/test_wrapper.py
index dafff65..e5a52c2 100644
--- a/matemat/db/test/test_wrapper.py
+++ b/matemat/db/test/test_wrapper.py
@@ -75,3 +75,29 @@ class DatabaseTest(unittest.TestCase):
             c = db._sqlite_db.cursor()
             c.execute("SELECT * FROM users")
             self.assertIsNone(c.fetchone())
+
+    def test_connect_twice(self):
+        """
+        If a connection is already established, a RuntimeError should be raised when attempting to connect a
+        second time.
+        """
+        self.db.connect()
+        with self.assertRaises(RuntimeError):
+            self.db.connect()
+        self.db.close()
+
+    def test_close_not_opened(self):
+        """
+        Attempting to close an unopened connection should raise a RuntimeError.
+        """
+        with self.assertRaises(RuntimeError):
+            self.db.close()
+
+    def test_close_in_transaction(self):
+        """
+        Attempting to close a connection inside a transaction should raise a RuntimeError.
+        """
+        with self.db as db:
+            with db.transaction():
+                with self.assertRaises(RuntimeError):
+                    self.db.close()