diff --git a/src/openflexure_microscope_server/things/system.py b/src/openflexure_microscope_server/things/system.py
index 67644070..12aaadf9 100644
--- a/src/openflexure_microscope_server/things/system.py
+++ b/src/openflexure_microscope_server/things/system.py
@@ -5,7 +5,7 @@ the microscope, server, and thing states to the web API.
 """
 
 from collections.abc import Mapping
-from socket import gethostname
+import socket
 from typing import Optional
 from uuid import UUID, uuid4
 import subprocess
@@ -19,6 +19,9 @@ import labthings_fastapi as lt
 
 from openflexure_microscope_server.utilities import VersionData, robust_version_strings
 
+SHUTDOWN_CMD = ["sudo", "shutdown", "-h", "now"]
+REBOOT_CMD = ["sudo", "shutdown", "-r", "now"]
+
 
 class CommandOutput(BaseModel):
     """A pydantic model passing the STDOUT and STDERR from a subprocess over HTTP."""
@@ -55,7 +58,7 @@ class OpenFlexureSystem(lt.Thing):
     @lt.thing_property
     def hostname(self) -> str:
         """The hostname of the microscope, as reported by its operating system."""
-        return gethostname()
+        return socket.gethostname()
 
     _version_data: Optional[VersionData] = None
 
@@ -93,7 +96,7 @@ class OpenFlexureSystem(lt.Thing):
 
         # On a Raspberry Pi
         p = subprocess.Popen(
-            ["sudo", "shutdown", "-h", "now"],
+            SHUTDOWN_CMD,
             stderr=subprocess.PIPE,
             stdout=subprocess.PIPE,
         )
@@ -111,7 +114,7 @@ class OpenFlexureSystem(lt.Thing):
             )
 
         p = subprocess.Popen(
-            ["sudo", "shutdown", "-r", "now"],
+            REBOOT_CMD,
             stderr=subprocess.PIPE,
             stdout=subprocess.PIPE,
         )
diff --git a/tests/test_system_thing.py b/tests/test_system_thing.py
new file mode 100644
index 00000000..d1fb4a1e
--- /dev/null
+++ b/tests/test_system_thing.py
@@ -0,0 +1,145 @@
+"""Test the OpenFlexureSystem Thing *without* connecting it to a LabThings Server."""
+
+import os
+from signal import SIGTERM
+from uuid import UUID
+
+from openflexure_microscope_server.things import system
+from openflexure_microscope_server.utilities import VersionData, robust_version_strings
+
+
+def _is_raspberrypi() -> bool:
+    """Check if the machine running the test is a Raspberry Pi.
+
+    This information is needed to check if the ``is_raspberrypi`` property of the Thing
+    is correct. This is implemented in a different way to in the main code.
+    """
+    # Check if the file specifying the Raspberry Pi model exists
+    if not os.path.isfile("/proc/device-tree/model"):
+        return False
+    with open("/proc/device-tree/model", "r", encoding="utf-8") as model_file:
+        model_name = model_file.read()
+    return "Raspberry Pi" in model_name
+
+
+def test_is_raspberry():
+    """Check the thing property reports whether this is a Raspberry Pi correctly."""
+    assert system.OpenFlexureSystem().is_raspberrypi == _is_raspberrypi()
+
+
+def test_version_data():
+    """Check VersionData is returned.
+
+    The content of robust_version_strings() is tested elsewhere.
+    """
+    system_thing = system.OpenFlexureSystem()
+    data = system_thing.version_data
+    assert isinstance(data, VersionData)
+    assert data == robust_version_strings()
+
+    fake_data = VersionData(version="fake", version_source="fake")
+    system_thing._version_data = fake_data
+    data = system_thing.version_data
+    assert data == fake_data
+
+
+def test_hostname(mocker):
+    """Check the hostname matches what socket.gethostname() returns."""
+    mock_gethostname = mocker.patch("socket.gethostname", return_value="foobar")
+    system_thing = system.OpenFlexureSystem()
+    assert system_thing.hostname == "foobar"
+    mock_gethostname.assert_called_once_with()
+
+
+def test_microscope_id():
+    """Check the microscope UUID is a valid UUID and doesn't change when read again."""
+    system_thing = system.OpenFlexureSystem()
+    microscope_id = system_thing.microscope_id
+    assert isinstance(microscope_id, UUID)
+    assert microscope_id == system_thing.microscope_id
+
+
+def test_thing_state(mocker):
+    """Check the thing state contains version data, hostname, and a UUID string."""
+    mocker.patch("socket.gethostname", return_value="foobar")
+    version_data = robust_version_strings()
+    system_thing = system.OpenFlexureSystem()
+    state_dict = system_thing.thing_state
+    assert state_dict["hostname"] == "foobar"
+    # Check the UUID in the dictionary is a string
+    assert isinstance(state_dict["microscope-uuid"], str)
+    # Check uuid string can be converted to valid UUID
+    UUID(state_dict["microscope-uuid"])
+    assert state_dict["version"] == version_data.version
+    assert state_dict["version_source"] == version_data.version_source
+
+
+class MockPiSystem(system.OpenFlexureSystem):
+    """A OpenFlexureSystem Thing that always claims to be a Raspberry Pi."""
+
+    is_raspberrypi: bool = True
+
+
+class MockNonPiSystem(system.OpenFlexureSystem):
+    """A OpenFlexureSystem Thing that never claims to be a Raspberry Pi."""
+
+    is_raspberrypi: bool = False
+
+
+def test_pi_shutdown(mocker):
+    """Check that on a Pi will receive the correct shutdown command."""
+    # Check the shutdown command is as expected.
+    assert system.SHUTDOWN_CMD == ["sudo", "shutdown", "-h", "now"]
+    # Mock the shutdown command as we don't want to shutdown when running tests.
+    mocker.patch.object(system, "SHUTDOWN_CMD", new=["echo", "shutdown"])
+    # Call shutdown on a MockPiSystem
+    system_thing = MockPiSystem()
+    result = system_thing.shutdown()
+
+    # Check the result of the echo mock command was returned
+    assert result.output.strip() == "shutdown"
+    assert result.error.strip() == ""
+
+
+def test_pi_reboot(mocker):
+    """Check that on a Pi will receive the correct reboot command."""
+    # Check the reboot command is as expected.
+    assert system.REBOOT_CMD == ["sudo", "shutdown", "-r", "now"]
+    # Mock the reboot command as we don't want to reboot when running tests.
+    mocker.patch.object(system, "REBOOT_CMD", new=["echo", "restart"])
+    # Call reboot on a MockPiSystem
+    system_thing = MockPiSystem()
+    result = system_thing.reboot()
+
+    # Check the result of the echo mock command was returned
+    assert result.output.strip() == "restart"
+    assert result.error.strip() == ""
+
+
+def test_non_pi_shutdown(mocker):
+    """Check that a server not on a pi runs os.kill when asked to shutdown.
+
+    It should do this instead of running the shutdown command in a subprocess.
+    """
+    # Mock os.kill
+    mock_kill = mocker.patch("os.kill")
+    # Get this subprocess
+    pid = os.getpid()
+    system_thing = MockNonPiSystem()
+    result = system_thing.shutdown()
+
+    # Check it tried to kill this process with SIGTERM
+    mock_kill.assert_called_once_with(pid, SIGTERM)
+    # Check output is an appropriate error message (that we have not shut down!)
+    assert result.output.strip() == ""
+    assert "but the server has not shutdown" in result.error
+
+
+def test_non_pi_reboot():
+    """Check that a server not on a pi refuses to restart."""
+    system_thing = MockNonPiSystem()
+    result = system_thing.reboot()
+
+    # Check output is an appropriate error message
+    assert result.output.strip() == ""
+    assert result.error.strip() == "Restart is only available on Raspberry Pi."