Add plumbing for passing credentials to devices (#507)

* Add plumbing for passing credentials as far as discovery

* Pass credentials to Smart devices

* Rename authentication exception

* Fix tests failure due to test_json_output leaving echo as nop

* Fix test_credentials test

* Do not print credentials, fix echo function bug and improve get type parameter

* Add device class constructor test

* Add comment for echo handling and move assignment

kasa/smartbulb.py

@@ -9,6 +9,7 @@ try:
 except ImportError:
     from pydantic import BaseModel, Field, root_validator
 
+from .credentials import Credentials
 from .modules import Antitheft, Cloud, Countdown, Emeter, Schedule, Time, Usage
 from .smartdevice import DeviceType, SmartDevice, SmartDeviceException, requires_update
 
@@ -202,8 +203,14 @@ class SmartBulb(SmartDevice):
     SET_LIGHT_METHOD = "transition_light_state"
     emeter_type = "smartlife.iot.common.emeter"
 
-    def __init__(self, host: str, *, port: Optional[int] = None) -> None:
-        super().__init__(host=host, port=port)
+    def __init__(
+        self,
+        host: str,
+        *,
+        port: Optional[int] = None,
+        credentials: Optional[Credentials] = None
+    ) -> None:
+        super().__init__(host=host, port=port, credentials=credentials)
         self._device_type = DeviceType.Bulb
         self.add_module("schedule", Schedule(self, "smartlife.iot.common.schedule"))
         self.add_module("usage", Usage(self, "smartlife.iot.common.schedule"))