update tests to look at side effects instead of internals

Subscribe command will enable notify or indicate events from the
characteristic, depending on supported characteristic properties, and
print received values to the output window.

Unsubscribe will stop notify or indicate events.

Rename find_attribute() to find_characteristic() and return a
characteristic for a set of UUIDS, a characteristic for an attribute
handle, or None.

Print read and received values has a hex string.

Add an unsubscribe implementation to gatt_client.py. Reset the CCCD bits
to 0x0000. Remove a matching subsciber, if one is provided. Otherwise
remove all subscribers for a characteristic, since no more notify or
indicates events will be comming.

authored-by: Michael Mogenson <mogenson@google.com>

.github/workflows/python-publish.yml

@@ -30,7 +30,7 @@ jobs:
     - name: Build package
       run: python -m build
     - name: Publish package to PyPI
-      if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
+      if: github.event_name == 'release' && startsWith(github.ref, 'refs/tags')
       uses: pypa/gh-action-pypi-publish@release/v1
       with:
         user: __token__

apps/console.py

@@ -122,6 +122,8 @@ class ConsoleApp:
                 },
                 'read': LiveCompleter(self.known_attributes),
                 'write': LiveCompleter(self.known_attributes),
+                'subscribe': LiveCompleter(self.known_attributes),
+                'unsubscribe': LiveCompleter(self.known_attributes),
                 'quit': None,
                 'exit': None
             })
@@ -331,7 +333,7 @@ class ConsoleApp:
 
         await self.show_attributes(attributes)
 
-    def find_attribute(self, param):
+    def find_characteristic(self, param):
         parts = param.split('.')
         if len(parts) == 2:
             service_uuid = UUID(parts[0]) if parts[0] != '*' else None
@@ -344,7 +346,10 @@ class ConsoleApp:
         elif len(parts) == 1:
             if parts[0].startswith('#'):
                 attribute_handle = int(f'{parts[0][1:]}', 16)
-                return attribute_handle
+                for service in self.connected_peer.services:
+                    for characteristic in service.characteristics:
+                        if characteristic.handle == attribute_handle:
+                            return characteristic
 
     async def command(self, command):
         try:
@@ -457,13 +462,13 @@ class ConsoleApp:
             self.show_error('invalid syntax', 'expected read <attribute>')
             return
 
-        attribute = self.find_attribute(params[0])
+        characteristic = self.find_characteristic(params[0])
-        if attribute is None:
+        if characteristic is None:
             self.show_error('no such characteristic')
             return
 
-        value = await self.connected_peer.read_value(attribute)
+        value = await characteristic.read_value()
-        self.append_to_output(f'VALUE: {value}')
+        self.append_to_output(f'VALUE: 0x{value.hex()}')
 
     async def do_write(self, params):
         if not self.connected_peer:
@@ -482,21 +487,48 @@ class ConsoleApp:
             except ValueError:
                 value = str.encode(params[1])  # must be a string
 
-        attribute = self.find_attribute(params[0])
+        characteristic = self.find_characteristic(params[0])
-        if attribute is None:
+        if characteristic is None:
             self.show_error('no such characteristic')
             return
 
         # use write with response if supported
-        with_response = (
+        with_response = characteristic.properties & Characteristic.WRITE
-            (attribute.properties & Characteristic.WRITE)
+        await characteristic.write_value(value, with_response=with_response)
-            if hasattr(attribute, "properties")
+
-            else False
+    async def do_subscribe(self, params):
+        if not self.connected_peer:
+            self.show_error('not connected')
+            return
+
+        if len(params) != 1:
+            self.show_error('invalid syntax', 'expected subscribe <attribute>')
+            return
+
+        characteristic = self.find_characteristic(params[0])
+        if characteristic is None:
+            self.show_error('no such characteristic')
+            return
+
+        await characteristic.subscribe(
+            lambda value: self.append_to_output(f"{characteristic} VALUE: 0x{value.hex()}"),
         )
 
-        await self.connected_peer.write_value(
+    async def do_unsubscribe(self, params):
-            attribute, value, with_response=with_response
+        if not self.connected_peer:
-        )
+            self.show_error('not connected')
+            return
+
+        if len(params) != 1:
+            self.show_error('invalid syntax', 'expected subscribe <attribute>')
+            return
+
+        characteristic = self.find_characteristic(params[0])
+        if characteristic is None:
+            self.show_error('no such characteristic')
+            return
+
+        await characteristic.unsubscribe()
 
     async def do_exit(self, params):
         self.ui.exit()

bumble/device.py

@@ -123,6 +123,9 @@ class Peer:
     async def subscribe(self, characteristic, subscriber=None):
         return await self.gatt_client.subscribe(characteristic, subscriber)
 
+    async def unsubscribe(self, characteristic, subscriber=None):
+        return await self.gatt_client.unsubscribe(characteristic, subscriber)
+
     async def read_value(self, attribute):
         return await self.gatt_client.read_value(attribute)
 

bumble/gatt_client.py

@@ -110,6 +110,9 @@ class CharacteristicProxy(AttributeProxy):
     async def subscribe(self, subscriber=None):
         return await self.client.subscribe(self, subscriber)
 
+    async def unsubscribe(self, subscriber=None):
+        return await self.client.unsubscribe(self, subscriber)
+
     def __str__(self):
         return f'Characteristic(handle=0x{self.handle:04X}, uuid={self.uuid}, properties={Characteristic.properties_as_string(self.properties)})'
 
@@ -544,10 +547,36 @@ class Client:
         for subscriber_set in subscriber_sets:
             if subscriber is not None:
                 subscriber_set.add(subscriber)
-            subscriber_set.add(lambda value: characteristic.emit('update', self.connection, value))
+            # Add the characteristic as a subscriber, which will result in the characteristic
+            # emitting an 'update' event when a notification or indication is received
+            subscriber_set.add(characteristic)
 
         await self.write_value(cccd, struct.pack('<H', bits), with_response=True)
 
+    async def unsubscribe(self, characteristic, subscriber=None):
+        # If we haven't already discovered the descriptors for this characteristic, do it now
+        if not characteristic.descriptors_discovered:
+            await self.discover_descriptors(characteristic)
+
+        # Look for the CCCD descriptor
+        cccd = characteristic.get_descriptor(GATT_CLIENT_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR)
+        if not cccd:
+            logger.warning('unsubscribing from characteristic with no CCCD descriptor')
+            return
+
+        if subscriber is not None:
+            # Remove matching subscriber from subscriber sets
+            for subscriber_set in (self.notification_subscribers, self.indication_subscribers):
+                subscribers = subscriber_set.get(characteristic.handle, [])
+                if subscriber in subscribers:
+                    subscribers.remove(subscriber)
+        else:
+            # Remove all subscribers for this attribute from the sets!
+            self.notification_subscribers.pop(characteristic.handle, None)
+            self.indication_subscribers.pop(characteristic.handle, None)
+
+        await self.write_value(cccd, b'\x00\x00', with_response=True)
+
     async def read_value(self, attribute, no_long_read=False):
         '''
         See Vol 3, Part G - 4.8.1 Read Characteristic Value
@@ -714,7 +743,10 @@ class Client:
         if not subscribers:
             logger.warning('!!! received notification with no subscriber')
         for subscriber in subscribers:
-            subscriber(notification.attribute_value)
+            if callable(subscriber):
+                subscriber(notification.attribute_value)
+            else:
+                subscriber.emit('update', notification.attribute_value)
 
     def on_att_handle_value_indication(self, indication):
         # Call all subscribers
@@ -722,7 +754,10 @@ class Client:
         if not subscribers:
             logger.warning('!!! received indication with no subscriber')
         for subscriber in subscribers:
-            subscriber(indication.attribute_value)
+            if callable(subscriber):
+                subscriber(indication.attribute_value)
+            else:
+                subscriber.emit('update', indication.attribute_value)
 
         # Confirm that we received the indication
         self.send_confirmation(ATT_Handle_Value_Confirmation())

tests/gatt_test.py

@@ -419,10 +419,12 @@ async def test_subscribe_notify():
     assert(len(c) == 1)
     c3 = c[0]
 
+    c1._called = False
     c1._last_update = None
 
-    def on_c1_update(connection, value):
+    def on_c1_update(value):
-        c1._last_update = (connection, value)
+        c1._called = True
+        c1._last_update = value
 
     c1.on('update', on_c1_update)
     await peer.subscribe(c1)
@@ -434,44 +436,73 @@ async def test_subscribe_notify():
     assert(not characteristic1._last_subscription[2])
     await server.indicate_subscribers(characteristic1)
     await async_barrier()
-    assert(c1._last_update is None)
+    assert(not c1._called)
     await server.notify_subscribers(characteristic1)
     await async_barrier()
-    assert(c1._last_update is not None)
+    assert(c1._called)
-    assert(c1._last_update[1] == characteristic1.value)
+    assert(c1._last_update == characteristic1.value)
 
+    c1._called = False
+    await peer.unsubscribe(c1)
+    await server.notify_subscribers(characteristic1)
+    assert(not c1._called)
+
+    c2._called = False
     c2._last_update = None
 
     def on_c2_update(value):
-        c2._last_update = (connection, value)
+        c2._called = True
+        c2._last_update = value
 
     await peer.subscribe(c2, on_c2_update)
     await async_barrier()
     await server.notify_subscriber(characteristic2._last_subscription[0], characteristic2)
     await async_barrier()
-    assert(c2._last_update is None)
+    assert(not c2._called)
     await server.indicate_subscriber(characteristic2._last_subscription[0], characteristic2)
     await async_barrier()
-    assert(c2._last_update is not None)
+    assert(c2._called)
-    assert(c2._last_update[1] == characteristic2.value)
+    assert(c2._last_update == characteristic2.value)
 
-    c3._last_update = None
+    c2._called = False
+    await peer.unsubscribe(c2, on_c2_update)
+    await server.indicate_subscriber(characteristic2._last_subscription[0], characteristic2)
+    await async_barrier()
+    assert(not c2._called)
 
-    def on_c3_update(connection, value):
+    def on_c3_update(value):
-        c3._last_update = (connection, value)
+        c3._called = True
+        c3._last_update = value
+
+    def on_c3_update_2(value):
+        c3._called_2 = True
+        c3._last_update_2 = value
 
     c3.on('update', on_c3_update)
-    await peer.subscribe(c3)
+    await peer.subscribe(c3, on_c3_update_2)
     await async_barrier()
     await server.notify_subscriber(characteristic3._last_subscription[0], characteristic3)
     await async_barrier()
-    assert(c3._last_update is not None)
+    assert(c3._called)
-    assert(c3._last_update[1] == characteristic3.value)
+    assert(c3._last_update == characteristic3.value)
+    assert(c3._called_2)
+    assert(c3._last_update_2 == characteristic3.value)
     characteristic3.value = bytes([1, 2, 3])
     await server.indicate_subscriber(characteristic3._last_subscription[0], characteristic3)
     await async_barrier()
-    assert(c3._last_update is not None)
+    assert(c3._called)
-    assert(c3._last_update[1] == characteristic3.value)
+    assert(c3._last_update == characteristic3.value)
+    assert(c3._called_2)
+    assert(c3._last_update_2 == characteristic3.value)
+
+    c3._called = False
+    c3._called_2 = False
+    await peer.unsubscribe(c3)
+    await server.notify_subscriber(characteristic3._last_subscription[0], characteristic3)
+    await server.indicate_subscriber(characteristic3._last_subscription[0], characteristic3)
+    await async_barrier()
+    assert(not c3._called)
+    assert(not c3._called_2)
 
 
 # -----------------------------------------------------------------------------