diff --git a/.coveragerc b/.coveragerc
index 5c70a1a..85bf3bb 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,2 +1,2 @@
 [run]
-omit = meshtastic/*_pb2.py,meshtastic/test.py
+omit = meshtastic/*_pb2.py,meshtastic/test.py,meshtastic/test/*.py
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4985df3..3acf7de 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,6 +29,6 @@ jobs:
           which meshtastic
           meshtastic --version
       - name: Run pylint
-        run: pylint --exit-zero meshtastic
+        run: pylint meshtastic
       - name: Run tests with pytest
         run: pytest --cov=meshtastic
diff --git a/meshtastic/serial_interface.py b/meshtastic/serial_interface.py
index 4f8ddf3..90b6922 100644
--- a/meshtastic/serial_interface.py
+++ b/meshtastic/serial_interface.py
@@ -6,8 +6,8 @@ import os
 import stat
 import serial
 
+import meshtastic.util
 from .stream_interface import StreamInterface
-from .util import findPorts, our_exit
 
 class SerialInterface(StreamInterface):
     """Interface class for meshtastic devices over a serial link"""
@@ -22,14 +22,14 @@ class SerialInterface(StreamInterface):
         """
 
         if devPath is None:
-            ports = findPorts()
+            ports = meshtastic.util.findPorts()
             logging.debug(f"ports:{ports}")
             if len(ports) == 0:
-                our_exit("Warning: No Meshtastic devices detected.")
+                meshtastic.util.our_exit("Warning: No Meshtastic devices detected.")
             elif len(ports) > 1:
                 message = "Warning: Multiple serial ports were detected so one serial port must be specified with the '--port'.\n"
                 message += f"  Ports detected:{ports}"
-                our_exit(message)
+                meshtastic.util.our_exit(message)
             else:
                 devPath = ports[0]
 
diff --git a/meshtastic/test/test_mesh_interface.py b/meshtastic/test/test_mesh_interface.py
index 77a5608..325c17a 100644
--- a/meshtastic/test/test_mesh_interface.py
+++ b/meshtastic/test/test_mesh_interface.py
@@ -1,15 +1,15 @@
-"""Meshtastic unit tests for node.py"""
+"""Meshtastic unit tests for mesh_interface.py"""
 
 import re
 
 import pytest
 
-from meshtastic.mesh_interface import MeshInterface
+from ..mesh_interface import MeshInterface
 
 
 @pytest.mark.unit
 def test_MeshInterface(capsys):
-    """Test that we instantiate a MeshInterface"""
+    """Test that we can instantiate a MeshInterface"""
     iface = MeshInterface(noProto=True)
     iface.showInfo()
     iface.localNode.showInfo()
diff --git a/meshtastic/test/test_serial_interface.py b/meshtastic/test/test_serial_interface.py
new file mode 100644
index 0000000..10b4dbc
--- /dev/null
+++ b/meshtastic/test/test_serial_interface.py
@@ -0,0 +1,49 @@
+"""Meshtastic unit tests for serial_interface.py"""
+
+import re
+
+
+from unittest.mock import patch
+import pytest
+
+from ..serial_interface import SerialInterface
+
+@pytest.mark.unit
+@patch('serial.Serial')
+@patch('meshtastic.util.findPorts', return_value=['/dev/ttyUSBfake'])
+def test_SerialInterface_single_port(mocked_findPorts, mocked_serial):
+    """Test that we can instantiate a SerialInterface with a single port"""
+    iface = SerialInterface(noProto=True)
+    iface.showInfo()
+    iface.localNode.showInfo()
+    iface.close()
+    mocked_findPorts.assert_called()
+    mocked_serial.assert_called()
+
+
+@pytest.mark.unit
+@patch('meshtastic.util.findPorts', return_value=[])
+def test_SerialInterface_no_ports(mocked_findPorts, capsys):
+    """Test that we can instantiate a SerialInterface with no ports"""
+    with pytest.raises(SystemExit) as pytest_wrapped_e:
+        SerialInterface(noProto=True)
+    mocked_findPorts.assert_called()
+    assert pytest_wrapped_e.type == SystemExit
+    assert pytest_wrapped_e.value.code == 1
+    out, err = capsys.readouterr()
+    assert re.search(r'Warning: No Meshtastic devices detected', out, re.MULTILINE)
+    assert err == ''
+
+
+@pytest.mark.unit
+@patch('meshtastic.util.findPorts', return_value=['/dev/ttyUSBfake1', '/dev/ttyUSBfake2'])
+def test_SerialInterface_multiple_ports(mocked_findPorts, capsys):
+    """Test that we can instantiate a SerialInterface with two ports"""
+    with pytest.raises(SystemExit) as pytest_wrapped_e:
+        SerialInterface(noProto=True)
+    mocked_findPorts.assert_called()
+    assert pytest_wrapped_e.type == SystemExit
+    assert pytest_wrapped_e.value.code == 1
+    out, err = capsys.readouterr()
+    assert re.search(r'Warning: Multiple serial ports were detected', out, re.MULTILINE)
+    assert err == ''
diff --git a/meshtastic/test/test_smoke1.py b/meshtastic/test/test_smoke1.py
index 242604f..a7f4b00 100644
--- a/meshtastic/test/test_smoke1.py
+++ b/meshtastic/test/test_smoke1.py
@@ -8,7 +8,7 @@ import os
 # sense to pause for the radio at apprpriate times
 import pytest
 
-import meshtastic
+from ..util import findPorts
 
 # seconds to pause after running a meshtastic command
 PAUSE_AFTER_COMMAND = 2
@@ -143,7 +143,7 @@ def test_smoke1_send_hello():
 def test_smoke1_port():
     """Test --port"""
     # first, get the ports
-    ports = meshtastic.util.findPorts()
+    ports = findPorts()
     # hopefully there is just one
     assert len(ports) == 1
     port = ports[0]
diff --git a/meshtastic/test/test_stream_interface.py b/meshtastic/test/test_stream_interface.py
new file mode 100644
index 0000000..57c65d2
--- /dev/null
+++ b/meshtastic/test/test_stream_interface.py
@@ -0,0 +1,14 @@
+"""Meshtastic unit tests for stream_interface.py"""
+
+
+import pytest
+
+from ..stream_interface import StreamInterface
+
+
+@pytest.mark.unit
+def test_StreamInterface():
+    """Test that we can instantiate a StreamInterface"""
+    with pytest.raises(Exception) as pytest_wrapped_e:
+        StreamInterface(noProto=True)
+    assert pytest_wrapped_e.type == Exception
diff --git a/meshtastic/test/test_tcp_interface.py b/meshtastic/test/test_tcp_interface.py
new file mode 100644
index 0000000..432caef
--- /dev/null
+++ b/meshtastic/test/test_tcp_interface.py
@@ -0,0 +1,26 @@
+"""Meshtastic unit tests for tcp_interface.py"""
+
+import re
+
+from unittest.mock import patch
+import pytest
+
+from ..tcp_interface import TCPInterface
+
+
+@pytest.mark.unit
+def test_TCPInterface(capsys):
+    """Test that we can instantiate a TCPInterface"""
+    with patch('socket.socket') as mock_socket:
+        iface = TCPInterface(hostname='localhost', noProto=True)
+        iface.showInfo()
+        iface.localNode.showInfo()
+        out, err = capsys.readouterr()
+        assert re.search(r'Owner: None \(None\)', out, re.MULTILINE)
+        assert re.search(r'Nodes', out, re.MULTILINE)
+        assert re.search(r'Preferences', out, re.MULTILINE)
+        assert re.search(r'Channels', out, re.MULTILINE)
+        assert re.search(r'Primary channel URL', out, re.MULTILINE)
+        assert err == ''
+        assert mock_socket.called
+        iface.close()
diff --git a/meshtastic/test/test_util.py b/meshtastic/test/test_util.py
index ea3253b..cf5f638 100644
--- a/meshtastic/test/test_util.py
+++ b/meshtastic/test/test_util.py
@@ -1,4 +1,4 @@
-"""Meshtastic unit tests for node.py"""
+"""Meshtastic unit tests for util.py"""
 
 import re