Work on #87

Implement a test suite, including Travis-CI integration

gpiozero/exc.py

@@ -4,16 +4,72 @@ from __future__ import (
     absolute_import,
     division,
 )
+str = type('')
 
-class GPIODeviceError(Exception):
-    pass
+
+class GPIOZeroError(Exception):
+    "Base class for all exceptions in GPIO Zero"
+
+class CompositeDeviceError(GPIOZeroError):
+    "Base class for errors specific to the CompositeDevice hierarchy"
+
+class GPIODeviceError(GPIOZeroError):
+    "Base class for errors specific to the GPIODevice hierarchy"
 
 class GPIODeviceClosed(GPIODeviceError):
-    pass
+    "Error raised when an operation is attempted on a closed device"
+
+class GPIOPinInUse(GPIODeviceError):
+    "Error raised when attempting to use a pin already in use by another device"
+
+class GPIOPinMissing(GPIODeviceError, ValueError):
+    "Error raised when a pin number is not specified"
+
+class GPIOBadQueueLen(GPIODeviceError, ValueError):
+    "Error raised when non-positive queue length is specified"
 
 class InputDeviceError(GPIODeviceError):
-    pass
+    "Base class for errors specific to the InputDevice hierarchy"
 
 class OutputDeviceError(GPIODeviceError):
-    pass
+    "Base class for errors specified to the OutputDevice hierarchy"
+
+class OutputDeviceBadValue(OutputDeviceError, ValueError):
+    "Error raised when ``value`` is set to an invalid value"
+
+class PinError(GPIOZeroError):
+    "Base class for errors related to pin implementations"
+
+class PinFixedFunction(PinError, AttributeError):
+    "Error raised when attempting to change the function of a fixed type pin"
+
+class PinInvalidFunction(PinError, ValueError):
+    "Error raised when attempting to change the function of a pin to an invalid value"
+
+class PinInvalidState(PinError, ValueError):
+    "Error raised when attempting to assign an invalid state to a pin"
+
+class PinInvalidPull(PinError, ValueError):
+    "Error raised when attempting to assign an invalid pull-up to a pin"
+
+class PinInvalidEdges(PinError, ValueError):
+    "Error raised when attempting to assign an invalid edge detection to a pin"
+
+class PinSetInput(PinError, AttributeError):
+    "Error raised when attempting to set a read-only pin"
+
+class PinFixedPull(PinError, AttributeError):
+    "Error raised when attempting to set the pull of a pin with fixed pull-up"
+
+class PinEdgeDetectUnsupported(PinError, AttributeError):
+    "Error raised when attempting to use edge detection on unsupported pins"
+
+class PinPWMError(PinError):
+    "Base class for errors related to PWM implementations"
+
+class PinPWMUnsupported(PinPWMError, AttributeError):
+    "Error raised when attempting to activate PWM on unsupported pins"
+
+class PinPWMFixedValue(PinPWMError, AttributeError):
+    "Error raised when attempting to initialize PWM on an input pin"