diff --git a/tests/test_uart.py b/tests/test_uart.py
index 8fbf38b..89ad45b 100644
--- a/tests/test_uart.py
+++ b/tests/test_uart.py
@@ -162,7 +162,7 @@ def test_send(gw):
     gw.send(b"\x23\x11")
     assert gw._transport.write.call_count == 1
     data = b"\x7E\x00\x02\x23\x7D\x31\xCB"
-    assert gw._transport.write.called_once_with(data)
+    gw._transport.write.assert_called_once_with(data)
 
 
 def test_escape(gw):
diff --git a/tox.ini b/tox.ini
index 10871c3..5ee39c4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py38, lint, black
+envlist = py38, py39, py310, py311, py312, lint, black
 skip_missing_interpreters = True
 
 [testenv]