add in simple ro attrib definition..

bitelab/__init__.py

@@ -72,6 +72,9 @@ def new_parse_socket_addr(domain, addr):
 
 tcp_server.parse_socket_addr = new_parse_socket_addr
 
+class SerialConsole(DefROAttribute):
+	defattrname = 'console'
+
 class BoardImpl:
 	def __init__(self, name, brdclass, options):
 		self.name = name
@@ -825,3 +828,13 @@ class TestBiteLab(unittest.IsolatedAsyncioTestCase):
 			'attrs': { 'power': True },
 		}
 		self.assertEqual(res.json(), info)
+
+class TestAttrs(unittest.IsolatedAsyncioTestCase):
+	async def test_serialconsole(self):
+		data = 'somepath'
+		sc = SerialConsole(data)
+
+		self.assertEqual(data, await sc.getvalue())
+
+		with self.assertRaises(TypeError):
+			await sc.setvalue(data)

bitelab/abstract.py

@@ -41,5 +41,19 @@ class Attribute:
 	async def setvalue(self, v): # pragma: no cover
 		raise NotImplementedError
 
+class ROAttribute(Attribute):
+	'''A read-only attribute class.  This implements setvalue, but
+	raises a TypeError when setvalue is called.'''
+
+	async def setvalue(self, v):
+		raise TypeError('%s is read-only.' % self.__class__.__name__)
+
+class DefROAttribute(ROAttribute):
+	def __init__(self, val):
+		self._value = val
+
+	async def getvalue(self):
+		return self._value
+
 class Power(Attribute):
 	defattrname = 'power'

bitelab/testing.py

@@ -30,5 +30,5 @@
 
 from .snmp import TestSNMPPower, TestSNMPWrapper
 from .data import TestDatabase
-from . import TestBiteLab, TestUnhashLRU
+from . import TestBiteLab, TestUnhashLRU, TestAttrs
 from .__main__ import TestClient