diff --git a/app/src/inverter.py b/app/src/inverter.py
index 7cb4a7a..dc224ee 100644
--- a/app/src/inverter.py
+++ b/app/src/inverter.py
@@ -1,15 +1,12 @@
 import asyncio
-import weakref
 import logging
 import json
 
 if __name__ == "app.src.inverter":
-    from app.src.iter_registry import IterRegistry
     from app.src.config import Config
     from app.src.mqtt import Mqtt
     from app.src.infos import Infos
 else:  # pragma: no cover
-    from iter_registry import IterRegistry
     from config import Config
     from mqtt import Mqtt
     from infos import Infos
@@ -17,7 +14,7 @@ else:  # pragma: no cover
 logger_mqtt = logging.getLogger('mqtt')
 
 
-class Inverter(metaclass=IterRegistry):
+class Inverter():
     '''class Inverter is a baseclass
 
     The class has some class method for managing common resources like a
@@ -40,8 +37,6 @@ class Inverter(metaclass=IterRegistry):
         async_create_remote(): Establish a client connection to the TSUN cloud
         async_publ_mqtt(): Publish data to MQTT broker
     '''
-    _registry = []
-
     @classmethod
     def class_init(cls) -> None:
         logging.debug('Inverter.class_init')
@@ -109,6 +104,3 @@ class Inverter(metaclass=IterRegistry):
         logging.info('Close MQTT Task')
         loop.run_until_complete(cls.mqtt.close())
         cls.mqtt = None
-
-    def __init__(self):
-        self._registry.append(weakref.ref(self))
diff --git a/app/src/inverter_base.py b/app/src/inverter_base.py
index 026b91b..bd7c700 100644
--- a/app/src/inverter_base.py
+++ b/app/src/inverter_base.py
@@ -1,3 +1,5 @@
+from abc import abstractmethod
+import weakref
 import asyncio
 import logging
 import traceback
@@ -6,6 +8,7 @@ from aiomqtt import MqttCodeError
 from asyncio import StreamReader, StreamWriter
 
 if __name__ == "app.src.inverter_base":
+    from app.src.iter_registry import AbstractIterMeta
     from app.src.inverter import Inverter
     from app.src.async_stream import StreamPtr
     from app.src.async_stream import AsyncStreamClient
@@ -13,6 +16,7 @@ if __name__ == "app.src.inverter_base":
     from app.src.config import Config
     from app.src.infos import Infos
 else:  # pragma: no cover
+    from iter_registry import AbstractIterMeta
     from inverter import Inverter
     from async_stream import StreamPtr
     from async_stream import AsyncStreamClient
@@ -23,11 +27,43 @@ else:  # pragma: no cover
 logger_mqtt = logging.getLogger('mqtt')
 
 
-class InverterBase(Inverter):
+class InverterIfc(metaclass=AbstractIterMeta):
+
+    @abstractmethod
+    def __init__(self, reader: StreamReader, writer: StreamWriter,
+                 config_id: str, prot_class,
+                 client_mode: bool):
+        pass  # pragma: no cover
+
+    @abstractmethod
+    def __enter__(self):
+        pass  # pragma: no cover
+
+    @abstractmethod
+    def __exit__(self, exc_type, exc, tb):
+        pass  # pragma: no cover
+
+    @abstractmethod
+    def healthy(self) -> bool:
+        pass  # pragma: no cover
+
+    @abstractmethod
+    async def disc(self, shutdown_started=False) -> None: 
+        pass  # pragma: no cover
+
+    @abstractmethod
+    async def async_create_remote(self) -> None:
+        pass  # pragma: no cover
+
+
+class InverterBase(InverterIfc, Inverter):
+    _registry = []
+
     def __init__(self, reader: StreamReader, writer: StreamWriter,
                  config_id: str, prot_class,
                  client_mode: bool = False):
-        super().__init__()
+        Inverter.__init__(self)
+        self._registry.append(weakref.ref(self))
         self.addr = writer.get_extra_info('peername')
         self.config_id = config_id
         self.prot_class = prot_class
diff --git a/app/src/iter_registry.py b/app/src/iter_registry.py
index b84e16f..884d849 100644
--- a/app/src/iter_registry.py
+++ b/app/src/iter_registry.py
@@ -1,3 +1,4 @@
+from abc import ABCMeta
 
 
 class IterRegistry(type):
@@ -6,3 +7,12 @@ class IterRegistry(type):
             obj = ref()
             if obj is not None:
                 yield obj
+
+
+class AbstractIterMeta(ABCMeta):
+    def __iter__(cls):
+        for ref in cls._registry:
+            obj = ref()
+            print(f'obj: {obj}')
+            if obj is not None:
+                yield obj
diff --git a/app/tests/test_inverter_base.py b/app/tests/test_inverter_base.py
new file mode 100644
index 0000000..e1f2f33
--- /dev/null
+++ b/app/tests/test_inverter_base.py
@@ -0,0 +1,153 @@
+# test_with_pytest.py
+import pytest
+import asyncio
+import sys,gc
+
+from mock import patch
+from enum import Enum
+from app.src.infos import Infos
+from app.src.config import Config
+from app.src.gen3.talent import Talent
+from app.src.inverter_base import InverterBase
+from app.src.singleton import Singleton
+from app.src.protocol_ifc import ProtocolIfcImpl
+from app.src.async_stream import AsyncStream, AsyncIfcImpl
+
+from app.tests.test_modbus_tcp import patch_mqtt_err, patch_mqtt_except, test_port, test_hostname
+
+pytest_plugins = ('pytest_asyncio',)
+
+# initialize the proxy statistics
+Infos.static_init()
+
+@pytest.fixture
+def config_conn():
+    Config.act_config = {
+        'mqtt':{
+            'host': test_hostname,
+            'port': test_port,
+            'user': '',
+            'passwd': ''
+        },
+        'ha':{
+            'auto_conf_prefix': 'homeassistant',
+            'discovery_prefix': 'homeassistant', 
+            'entity_prefix': 'tsun',
+            'proxy_node_id': 'test_1',
+            'proxy_unique_id': ''
+        },
+        'tsun':{'enabled': True, 'host': 'test_cloud.local', 'port': 1234}, 'inverters':{'allow_all':True}
+    }
+
+@pytest.fixture(scope="module", autouse=True)
+def module_init():
+    Singleton._instances.clear()
+    yield
+
+class FakeReader():
+    def __init__(self):
+        self.on_recv =  asyncio.Event()
+    async def read(self, max_len: int):
+        await self.on_recv.wait()
+        return b''
+    def feed_eof(self):
+        return
+
+
+class FakeWriter():
+    def write(self, buf: bytes):
+        return
+    def get_extra_info(self, sel: str):
+        if sel == 'peername':
+            return 'remote.intern'
+        elif sel == 'sockname':
+            return 'sock:1234'
+        assert False
+    def is_closing(self):
+        return False
+    def close(self):
+        return
+    async def wait_closed(self):
+        return
+
+class TestType(Enum):
+    RD_TEST_0_BYTES = 1
+    RD_TEST_TIMEOUT = 2
+    RD_TEST_EXCEPT = 3
+
+
+test  = TestType.RD_TEST_0_BYTES
+
+@pytest.fixture
+def patch_open_connection():
+    async def new_conn(conn):
+        await asyncio.sleep(0)
+        return FakeReader(), FakeWriter()
+    
+    def new_open(host: str, port: int):
+        global test
+        if test == TestType.RD_TEST_TIMEOUT:
+            raise ConnectionRefusedError
+        elif test == TestType.RD_TEST_EXCEPT:
+            raise ValueError("Value cannot be negative") # Compliant
+        return new_conn(None)
+
+    with patch.object(asyncio, 'open_connection', new_open) as conn:
+        yield conn
+
+
+@pytest.fixture
+def patch_healthy():
+    with patch.object(AsyncStream, 'healthy') as conn:
+        yield conn
+
+def test_protocol_iter():
+    ProtocolIfcImpl._registry.clear()
+    cnt = 0
+    ifc = AsyncIfcImpl()
+    prot = ProtocolIfcImpl(('test.intern', 123), ifc, True)
+    for p in ProtocolIfcImpl:
+        assert p == prot
+        cnt += 1
+        del p
+    del prot
+    assert cnt == 1
+    for p in ProtocolIfcImpl:
+        assert False
+
+def test_inverter_iter():
+    InverterBase._registry.clear()
+    cnt = 0
+    reader = FakeReader()
+    writer =  FakeWriter()
+
+    with InverterBase(reader, writer, 'tsun', Talent) as inverter:
+        for inv in InverterBase:
+            assert inv == inverter
+            cnt += 1
+            del inv
+    del inverter
+    assert cnt == 1
+    
+    for inv in InverterBase:
+        assert False
+
+def test_method_calls(patch_healthy):
+    spy = patch_healthy
+    InverterBase._registry.clear()
+    reader = FakeReader()
+    writer =  FakeWriter()
+
+    with InverterBase(reader, writer, 'tsun', Talent) as inverter:
+        assert inverter.local.stream
+        assert inverter.local.ifc
+        # inverter.healthy()
+        for inv in InverterBase:
+            inv.healthy()
+            del inv
+        spy.assert_called_once()
+    del inverter
+    cnt = 0
+    for inv in InverterBase:
+        cnt += 1
+    assert cnt == 0
diff --git a/app/tests/test_inverter_g3.py b/app/tests/test_inverter_g3.py
index 2fbe4e8..702186a 100644
--- a/app/tests/test_inverter_g3.py
+++ b/app/tests/test_inverter_g3.py
@@ -8,6 +8,7 @@ from enum import Enum
 from app.src.infos import Infos
 from app.src.config import Config
 from app.src.inverter import Inverter
+from app.src.inverter_base import InverterBase
 from app.src.singleton import Singleton
 from app.src.gen3.inverter_g3 import InverterG3
 from app.src.async_stream import AsyncStream
@@ -103,18 +104,18 @@ def test_method_calls(patch_healthy):
     spy = patch_healthy
     reader = FakeReader()
     writer =  FakeWriter()
-    Inverter._registry.clear()
-    
+    InverterBase._registry.clear()
+
     with InverterG3(reader, writer) as inverter:
         assert inverter.local.stream
         assert inverter.local.ifc
-        for inv in Inverter:
+        for inv in InverterBase:
             inv.healthy()
             del inv
         spy.assert_called_once()
     del inverter
     cnt = 0
-    for inv in Inverter:
+    for inv in InverterBase:
         cnt += 1
     assert cnt == 0
 
@@ -131,7 +132,7 @@ async def test_remote_conn(config_conn, patch_open_connection):
     del inverter
 
     cnt = 0
-    for inv in Inverter:
+    for inv in InverterBase:
         print(f'Inverter refs:{gc.get_referrers(inv)}')
         cnt += 1
     assert cnt == 0
@@ -157,8 +158,8 @@ async def test_remote_except(config_conn, patch_open_connection):
     del inverter
 
     cnt = 0
-    for inv in Inverter:
-        print(f'Inverter refs:{gc.get_referrers(inv)}')
+    for inv in InverterBase:
+        print(f'InverterBase refs:{gc.get_referrers(inv)}')
         cnt += 1
     assert cnt == 0
 
diff --git a/app/tests/test_inverter_g3p.py b/app/tests/test_inverter_g3p.py
index 603d356..f25b768 100644
--- a/app/tests/test_inverter_g3p.py
+++ b/app/tests/test_inverter_g3p.py
@@ -7,6 +7,7 @@ from enum import Enum
 from app.src.infos import Infos
 from app.src.config import Config
 from app.src.inverter import Inverter
+from app.src.inverter_base import InverterBase
 from app.src.singleton import Singleton
 from app.src.gen3plus.inverter_g3p import InverterG3P
 
@@ -96,7 +97,7 @@ def patch_open_connection():
 def test_method_calls():
     reader = FakeReader()
     writer =  FakeWriter()
-    Inverter._registry.clear()
+    InverterBase._registry.clear()
 
     with InverterG3P(reader, writer, client_mode=False) as inverter:
         assert inverter.local.stream