Abstract away platform-dependent pin references

Quote taken straight from the docstring of get_pin:

>Cross-platform method to find a pin by string.
>
>The pin definitions are platform-dependent, but this provides
>a way to say "I'm using pin D20" without rolling a D20 and
>having to actually learn MicroPython/CircuitPython and the
>differences in how they handle pinouts.
>
>This also makes the keymap sanity checker actually work for
>CircuitPython boards, since it's not possible in CPY to
>define a module stub for `board` that uses Passthrough
>natively (which is how the MicroPython stub worked originally)

kmk/common/pins.py

@@ -0,0 +1,40 @@
+try:
+    import board
+
+    PLATFORM = 'CircuitPython'
+    PIN_SOURCE = board
+except ImportError:
+    import machine
+
+    PLATFORM = 'MicroPython'
+    PIN_SOURCE = machine.Pin.board
+except ImportError:
+    from kmk.common.types import Passthrough
+
+    PLATFORM = 'Unit Testing'
+    PIN_SOURCE = Passthrough()
+
+
+def get_pin(pin):
+    '''
+    Cross-platform method to find a pin by string.
+
+    The pin definitions are platform-dependent, but this provides
+    a way to say "I'm using pin D20" without rolling a D20 and
+    having to actually learn MicroPython/CircuitPython and the
+    differences in how they handle pinouts.
+
+    This also makes the keymap sanity checker actually work for
+    CircuitPython boards, since it's not possible in CPY to
+    define a module stub for `board` that uses Passthrough
+    natively (which is how the MicroPython stub worked originally)
+    '''
+    return getattr(PIN_SOURCE, pin)
+
+
+class PinLookup:
+    def __getattr__(self, attr):
+        return get_pin(attr)
+
+
+Pin = PinLookup()

kmk/common/types.py

@@ -8,3 +8,19 @@ class AttrDict(dict):
     '''
     def __getattr__(self, key):
         return self[key]
+
+
+class Anything:
+    '''
+    A stub class which will repr as a provided name
+    '''
+    def __init__(self, name):
+        self.name = name
+
+    def __repr__(self):
+        return 'Anything<{}>'.format(self.name)
+
+
+class Passthrough:
+    def __getattr__(self, attr):
+        return Anything(attr)

user_keymaps/kdb424/handwire_planck_pyboard.py

@@ -1,14 +1,11 @@
-import machine
-
 from kmk.common.consts import DiodeOrientation, UnicodeModes
 from kmk.common.keycodes import KC
 from kmk.common.macros.unicode import unicode_sequence
+from kmk.common.pins import Pin as P
 from kmk.entrypoints.handwire.pyboard import main
 
-p = machine.Pin.board
-
-cols = (p.Y12, p.Y11, p.Y10, p.Y9, p.X8, p.X7, p.X6, p.X5, p.X4, p.X3, p.X2, p.X1)
-rows = (p.Y1, p.Y2, p.Y3, p.Y4)
+cols = (P.Y12, P.Y11, P.Y10, P.Y9, P.X8, P.X7, P.X6, P.X5, P.X4, P.X3, P.X2, P.X1)
+rows = (P.Y1, P.Y2, P.Y3, P.Y4)
 
 diode_orientation = DiodeOrientation.COLUMNS
 

user_keymaps/klardotsh/feather_m4_express/fourfour.py

@@ -1,14 +1,13 @@
-import board
-
 from kmk.common.consts import DiodeOrientation, UnicodeModes
 from kmk.common.keycodes import KC
 from kmk.common.macros.simple import send_string, simple_key_sequence
 from kmk.common.macros.unicode import unicode_sequence
+from kmk.common.pins import Pin as P
 from kmk.entrypoints.handwire.feather_m4_express import main
 from kmk.firmware import Firmware
 
-cols = (board.D11, board.D10, board.D9)
-rows = (board.A2, board.A3, board.A4, board.A5)
+cols = (P.D11, P.D10, P.D9)
+rows = (P.A2, P.A3, P.A4, P.A5)
 
 diode_orientation = DiodeOrientation.COLUMNS
 unicode_mode = UnicodeModes.LINUX

user_keymaps/klardotsh/itsybitsy_m4_express/threethree.py

@@ -1,14 +1,13 @@
-import board
-
 from kmk.common.consts import DiodeOrientation, UnicodeModes
 from kmk.common.keycodes import KC
 from kmk.common.macros.simple import send_string, simple_key_sequence
 from kmk.common.macros.unicode import unicode_sequence
+from kmk.common.pins import Pin as P
 from kmk.entrypoints.handwire.itsybitsy_m4_express import main
 from kmk.firmware import Firmware
 
-cols = (board.A4, board.A5, board.D13)
-rows = (board.D12, board.D11, board.D10)
+cols = (P.A4, P.A5, P.D13)
+rows = (P.D12, P.D11, P.D10)
 
 diode_orientation = DiodeOrientation.COLUMNS
 unicode_mode = UnicodeModes.LINUX

user_keymaps/klardotsh/threethree_matrix_pyboard.py

@@ -1,14 +1,12 @@
-import machine
-
 from kmk.common.consts import DiodeOrientation, UnicodeModes
 from kmk.common.keycodes import KC
 from kmk.common.macros.simple import send_string, simple_key_sequence
 from kmk.common.macros.unicode import unicode_sequence
+from kmk.common.pins import Pin as P
 from kmk.entrypoints.handwire.pyboard import main
 
-p = machine.Pin.board
-cols = (p.X10, p.X11, p.X12)
-rows = (p.X1, p.X2, p.X3)
+cols = (P.X10, P.X11, P.X12)
+rows = (P.X1, P.X2, P.X3)
 
 diode_orientation = DiodeOrientation.COLUMNS
 unicode_mode = UnicodeModes.LINUX