Merge #547

547: highlevel: avoid returning a generic resource info for a non-int board r=MatthieuDartiailh a=MatthieuDartiailh

This typically happens for serial resource on Linux where we end up ASRL/dev/tty0::INSTR. Without this change users have to specify the resource class they want.

- [x] Executed ``black . && isort -c . && flake8`` with no errors
- [x] The change is fully covered by automated unit tests
- [x] Added an entry to the CHANGES file


Co-authored-by: MatthieuDartiailh <marul@laposte.net>

.pre-commit-config.yaml

@@ -1,19 +1,19 @@
 repos:
 - repo: https://github.com/pre-commit/mirrors-isort
-  rev: v4.3.21
+  rev: v5.5.3
   hooks:
     - id: isort
 - repo: https://github.com/psf/black
-  rev: stable
+  rev: 20.8b1
   hooks:
     - id: black
       language_version: python3.7
-- repo: https://github.com/pre-commit/pre-commit-hooks
-  rev: v2.3.0
+- repo: https://gitlab.com/pycqa/flake8
+  rev: 3.8.3
   hooks:
     - id: flake8
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: ''  # Use the sha / tag you want to point at
+  rev: v0.782  # Use the sha / tag you want to point at
   hooks:
     - id: mypy
       additional_dependencies: [numpy, typing_extensions]

CHANGES

@@ -6,6 +6,9 @@ PyVISA Changelog
 
 - fix the listing of available backends (Also not that we now return the backend
   name as can be used to create a ResourceManger) PR #545
+- allow a None value for the board value of a ResourceInfo PR #547
+  This allows for funky resource name such ASRL/dev/tty0::INSTR which are common
+  in pyvisa-py and avoid returning a completely generic resource in those cases.
 
 1.11 (16-09-2020)
 -----------------

pyvisa/highlevel.py

@@ -60,16 +60,18 @@
 #: Named tuple with information about a resource. Returned by some :class:`ResourceManager` methods.
 #:
 #: :interface_type: Interface type of the given resource string. :class:`pyvisa.constants.InterfaceType`
-#: :interface_board_number: Board number of the interface of the given resource string.
+#: :interface_board_number: Board number of the interface of the given resource string. We allow None
+#:                          since serial resources may not sometimes be easily described
+#:                          by a single number in particular on Linux system.
 #: :resource_class: Specifies the resource class (for example, "INSTR") of the given resource string.
 #: :resource_name: This is the expanded version of the given resource string.
-#:                       The format should be similar to the VISA-defined canonical resource name.
+#:                 The format should be similar to the VISA-defined canonical resource name.
 #: :alias: Specifies the user-defined alias for the given resource string.
 ResourceInfo = NamedTuple(
     "ResourceInfo",
     (
         ("interface_type", constants.InterfaceType),
-        ("interface_board_number", int),
+        ("interface_board_number", Optional[int]),
         ("resource_class", Optional[str]),
         ("resource_name", Optional[str]),
         ("alias", Optional[str]),
@@ -2036,29 +2038,36 @@ def parse_resource_extended(
         """
         try:
             parsed = rname.parse_resource_name(resource_name)
-
-            return (
-                ResourceInfo(
-                    parsed.interface_type_const,
-                    # We can only get concrete classes which have one of those
-                    # attributes
-                    int(
-                        parsed.board  # type: ignore
-                        if hasattr(parsed, "board")
-                        else parsed.interface  # type: ignore
-                    ),
-                    parsed.resource_class,
-                    str(parsed),
-                    None,
-                ),
-                StatusCode.success,
-            )
         except ValueError:
             return (
                 ResourceInfo(constants.InterfaceType.unknown, 0, None, None, None),
                 StatusCode.error_invalid_resource_name,
             )
 
+        board_number: Optional[int]
+        try:
+            # We can only get concrete classes which have one of those attributes
+            board_number = int(
+                parsed.board  # type: ignore
+                if hasattr(parsed, "board")
+                else parsed.interface  # type: ignore
+            )
+        # In some cases the board number may not be convertible to an int
+        # PyVISA-py serial resources on Linux for example
+        except ValueError:
+            board_number = None
+
+        return (
+            ResourceInfo(
+                parsed.interface_type_const,
+                board_number,
+                parsed.resource_class,
+                str(parsed),
+                None,
+            ),
+            StatusCode.success,
+        )
+
     def peek_8(
         self, session: VISASession, address: VISAMemoryAddress
     ) -> Tuple[int, StatusCode]:

pyvisa/testsuite/test_highlevel.py

@@ -19,26 +19,50 @@ class TestHighlevel(BaseTestCase):
 
     CHECK_NO_WARNING = False
 
-    def test_base_class_parse_resource(self):
+    @pytest.mark.parametrize(
+        "rsc_name, values",
+        [
+            ("TCPIP::192.168.0.1::INSTR", (constants.InterfaceType.tcpip, 0, "INSTR")),
+            ("TCPIP1::192.168.0.1::INSTR", (constants.InterfaceType.tcpip, 1, "INSTR")),
+            (
+                "TCPIP::192.168.0.1::5000::SOCKET",
+                (constants.InterfaceType.tcpip, 0, "SOCKET"),
+            ),
+            (
+                "TCPIP2::192.168.0.1::5000::SOCKET",
+                (constants.InterfaceType.tcpip, 2, "SOCKET"),
+            ),
+            ("GPIB::1::INSTR", (constants.InterfaceType.gpib, 0, "INSTR")),
+            ("GPIB::INTFC", (constants.InterfaceType.gpib, 0, "INTFC")),
+            ("GPIB2::1::INSTR", (constants.InterfaceType.gpib, 2, "INSTR")),
+            ("GPIB3::INTFC", (constants.InterfaceType.gpib, 3, "INTFC")),
+            (
+                "USB1::0x1111::0x2222::0x4445::0::RAW",
+                (constants.InterfaceType.usb, 1, "RAW"),
+            ),
+            (
+                "USB0::0x1112::0x2223::0x1234::0::INSTR",
+                (constants.InterfaceType.usb, 0, "INSTR"),
+            ),
+            ("ASRL2::INSTR", (constants.InterfaceType.asrl, 2, "INSTR")),
+            ("ASRL/dev/tty0::INSTR", (constants.InterfaceType.asrl, None, "INSTR")),
+        ],
+    )
+    def test_base_class_parse_resource(self, rsc_name, values):
         """Test the base class implementation of parse_resource."""
         lib = highlevel.VisaLibraryBase("test")
-        rsc_name = "TCPIP::192.168.0.1::INSTR"
         info, ret_code = lib.parse_resource(None, rsc_name)
 
         # interface_type interface_board_number resource_class resource_name alias
-        for parsed, value in zip(
-            info, (constants.InterfaceType.tcpip, 0, None, None, None)
-        ):
+        for parsed, value in zip(info, values[:2] + (None, None, None)):
             assert parsed == value
 
         info, ret_code = lib.parse_resource_extended(None, rsc_name)
         # interface_type interface_board_number resource_class resource_name alias
         for parsed, value in zip(
             info,
-            (
-                constants.InterfaceType.tcpip,
-                0,
-                "INSTR",
+            values
+            + (
                 rname.to_canonical_name(rsc_name),
                 None,
             ),