Avoid calling pformat unless debug logging is enabled (#217)

* Avoid calling pformat unless debug logging is enabled

* add logging test

* isort

* check for debug logging

* formatting

kasa/tests/test_protocol.py

@@ -1,4 +1,5 @@
 import json
+import logging
 import struct
 import sys
 
@@ -64,6 +65,39 @@ async def test_protocol_reconnect(mocker, retry_count):
     assert response == {"great": "success"}
 
 
+@pytest.mark.skipif(sys.version_info < (3, 8), reason="3.8 is first one with asyncmock")
+@pytest.mark.parametrize("log_level", [logging.WARNING, logging.DEBUG])
+async def test_protocol_logging(mocker, caplog, log_level):
+    caplog.set_level(log_level)
+    logging.getLogger("kasa").setLevel(log_level)
+    encrypted = TPLinkSmartHomeProtocol.encrypt('{"great":"success"}')[
+        TPLinkSmartHomeProtocol.BLOCK_SIZE :
+    ]
+
+    async def _mock_read(byte_count):
+        nonlocal encrypted
+        if byte_count == TPLinkSmartHomeProtocol.BLOCK_SIZE:
+            return struct.pack(">I", len(encrypted))
+        if byte_count == len(encrypted):
+            return encrypted
+        raise ValueError(f"No mock for {byte_count}")
+
+    def aio_mock_writer(_, __):
+        reader = mocker.patch("asyncio.StreamReader")
+        writer = mocker.patch("asyncio.StreamWriter")
+        mocker.patch.object(reader, "readexactly", _mock_read)
+        return reader, writer
+
+    protocol = TPLinkSmartHomeProtocol("127.0.0.1")
+    mocker.patch("asyncio.open_connection", side_effect=aio_mock_writer)
+    response = await protocol.query({})
+    assert response == {"great": "success"}
+    if log_level == logging.DEBUG:
+        assert "success" in caplog.text
+    else:
+        assert "success" not in caplog.text
+
+
 def test_encrypt():
     d = json.dumps({"foo": 1, "bar": 2})
     encrypted = TPLinkSmartHomeProtocol.encrypt(d)