aioble/multitests: Add re-registration multitest.

Test that singleton service/characteristic instances can be
re-registered across multiple stop/start cycles without data loss.
Verifies initial= values persist and writable characteristics
accept cycle-specific values after each re-registration.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: pi-anl

micropython/bluetooth/aioble/multitests/ble_reregister.py

@@ -0,0 +1,114 @@
+# Test that singleton service/characteristic instances can be re-registered
+# across multiple stop/start cycles without data loss.
+
+import sys
+
+# ruff: noqa: E402
+sys.path.append("")
+
+from micropython import const
+import machine
+import time
+
+import asyncio
+import aioble
+import bluetooth
+
+TIMEOUT_MS = 5000
+
+SERVICE_UUID = bluetooth.UUID("A5A5A5A5-FFFF-9999-1111-5A5A5A5A5A5A")
+CHAR_INITIAL_UUID = bluetooth.UUID("00000000-1111-2222-3333-444444444444")
+CHAR_WRITE_UUID = bluetooth.UUID("00000000-1111-2222-3333-555555555555")
+
+
+# Acting in peripheral role.
+async def instance0_task():
+    # Create service and characteristics ONCE (singleton pattern).
+    service = aioble.Service(SERVICE_UUID)
+    aioble.Characteristic(service, CHAR_INITIAL_UUID, read=True, initial=b"hello")
+    char_write = aioble.Characteristic(service, CHAR_WRITE_UUID, read=True, write=True)
+
+    multitest.globals(BDADDR=aioble.config("mac"))
+    multitest.next()
+
+    for i in range(3):
+        # Re-register the same service instances.
+        aioble.register_services(service)
+
+        # Write a cycle-specific value to the writable characteristic.
+        char_write.write("periph{}".format(i))
+
+        multitest.broadcast("connect-{}".format(i))
+
+        # Wait for central to connect.
+        print("advertise", i)
+        connection = await aioble.advertise(
+            20_000, adv_data=b"\x02\x01\x06\x04\xffMPY", timeout_ms=TIMEOUT_MS
+        )
+        print("connected", i)
+
+        # Wait for the central to write.
+        await char_write.written(timeout_ms=TIMEOUT_MS)
+        print("written", i)
+
+        # Wait for the central to disconnect.
+        await connection.disconnected(timeout_ms=TIMEOUT_MS)
+        print("disconnected", i)
+
+        # Shutdown aioble.
+        print("shutdown", i)
+        aioble.stop()
+
+        await asyncio.sleep_ms(100)
+
+
+def instance0():
+    try:
+        asyncio.run(instance0_task())
+    finally:
+        aioble.stop()
+
+
+# Acting in central role.
+async def instance1_task():
+    multitest.next()
+
+    for i in range(3):
+        multitest.wait("connect-{}".format(i))
+
+        # Connect to peripheral.
+        print("connect", i)
+        device = aioble.Device(*BDADDR)
+        connection = await device.connect(timeout_ms=TIMEOUT_MS)
+
+        # Discover characteristics.
+        service = await connection.service(SERVICE_UUID)
+        char_initial = await service.characteristic(CHAR_INITIAL_UUID)
+        char_write = await service.characteristic(CHAR_WRITE_UUID)
+
+        # Read the initial= characteristic — must be the same every cycle.
+        print("read initial", await char_initial.read(timeout_ms=TIMEOUT_MS))
+
+        # Read the writable characteristic — should have cycle-specific value.
+        print("read written", await char_write.read(timeout_ms=TIMEOUT_MS))
+
+        # Write to the writable characteristic.
+        print("write", i)
+        await char_write.write("central{}".format(i), response=True, timeout_ms=TIMEOUT_MS)
+
+        # Disconnect from peripheral.
+        print("disconnect", i)
+        await connection.disconnect(timeout_ms=TIMEOUT_MS)
+        print("disconnected", i)
+
+        # Shutdown aioble.
+        aioble.stop()
+
+        await asyncio.sleep_ms(100)
+
+
+def instance1():
+    try:
+        asyncio.run(instance1_task())
+    finally:
+        aioble.stop()