Merge pull request #722 from ImperialCollegeLondon/fix-device-enumera…

…tion-macos

Fix sorting of port names without terminating numbers

finesse/hardware/serial_device.py

@@ -28,13 +28,20 @@ def _port_info_to_str(vendor_id: int, product_id: int, count: int = 0) -> str:
     return out
 
 
-def _get_port_number(port: str) -> int:
-    """Get the port number from the end of a port's name."""
-    match = re.match("[^0-9]*([0-9]+)$", port)
-    if not match:
-        raise ValueError(f"Port {port} does not end with a number")
+def _get_port_parts(port: str) -> tuple[str, int]:
+    """Split the port name into the string prefix and the number suffix.
 
-    return int(match.group(1))
+    If there is no number at the end of the string, (port, -1) will be returned.
+    """
+    match = re.match("^([^0-9])*([0-9]*)$", port)
+
+    # NB: This should never fail as the regex should encompass all strings
+    assert match, "Invalid port name"
+
+    num_str = match.group(2)
+    num = int(num_str) if num_str else -1
+
+    return match.group(1), num
 
 
 def _get_usb_serial_ports(refresh: bool = False) -> dict[str, str]:
@@ -55,7 +62,7 @@ def _get_usb_serial_ports(refresh: bool = False) -> dict[str, str]:
     # additional number to distinguish them
     counter: dict[tuple[int, int], int] = {}
     _serial_ports = {}
-    for port in sorted(comports(), key=lambda port: _get_port_number(port.device)):
+    for port in sorted(comports(), key=lambda port: _get_port_parts(port.device)):
         # Vendor ID is a USB-specific field, so we can use this to check whether the
         # device is USB or not
         if port.vid is None:

tests/hardware/test_serial_device.py

@@ -9,7 +9,7 @@
 from finesse.hardware.serial_device import (
     SerialDevice,
     _create_serial,
-    _get_port_number,
+    _get_port_parts,
     _get_usb_serial_ports,
     _port_info_to_str,
 )
@@ -57,23 +57,14 @@ def test_get_usb_serial_ports(
         }
 
 
-@pytest.mark.parametrize(
-    "port,number",
-    (
-        (f"{prefix}{number}", number)
-        for number in (1, 2, 10)
-        for prefix in ("COM", "/dev/ttyUSB")
-    ),
-)
-def test_get_port_number(port: str, number: int) -> None:
-    """Test _get_port_number()."""
-    assert _get_port_number(port) == number
-
-
-def test_get_port_number_bad() -> None:
-    """Test _get_port_number() when a bad value is provided."""
-    with pytest.raises(ValueError):
-        _get_port_number("NO_NUMBER")
+def test_get_port_parts() -> None:
+    """Test _get_port_parts()."""
+    for prefix in ("COM", "/dev/ttyUSB"):
+        assert _get_port_parts(f"{prefix}1") < _get_port_parts(f"{prefix}2")
+        assert _get_port_parts(f"{prefix}1") < _get_port_parts(f"{prefix}10")
+    assert _get_port_parts("A1") < _get_port_parts("B1")
+    assert _get_port_parts("A") < _get_port_parts("A0")
+    assert _get_port_parts("A") < _get_port_parts("B")
 
 
 @pytest.mark.parametrize("refresh", (False, True))