From 098d62d1a15c6e9f114f3f206158f1a221ede856 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Colomb?= <src@andre.colomb.de>
Date: Tue, 5 May 2026 22:15:41 +0200
Subject: [PATCH 1/2] Add unit tests for Variable class.

---
 test/test_od.py       |  4 +++
 test/test_sdo.py      |  3 ++
 test/test_variable.py | 65 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 test/test_variable.py

diff --git a/test/test_od.py b/test/test_od.py
index 231a58dd..2f79b918 100644
--- a/test/test_od.py
+++ b/test/test_od.py
@@ -260,6 +260,10 @@ def test_get_item_index(self):
         self.assertIsInstance(item, od.ODArray)
         self.assertIs(item, array)
 
+    def test_get_variable_not_found(self):
+        test_od = od.ObjectDictionary()
+        self.assertIsNone(test_od.get_variable(0x9999))
+
 
 class TestArray(unittest.TestCase):
 
diff --git a/test/test_sdo.py b/test/test_sdo.py
index a9418716..ebf7a8f3 100644
--- a/test/test_sdo.py
+++ b/test/test_sdo.py
@@ -54,6 +54,9 @@ def test_array_contains_non_int(self):
         self.assertNotIn("not an int", array)
         self.assertNotIn(None, array)
 
+    def test_get_variable_not_found(self):
+        self.assertIsNone(self.sdo_node.get_variable(0x9999))
+
 
 class TestSDO(unittest.TestCase):
     """
diff --git a/test/test_variable.py b/test/test_variable.py
new file mode 100644
index 00000000..51250bd1
--- /dev/null
+++ b/test/test_variable.py
@@ -0,0 +1,65 @@
+import unittest
+
+from canopen import objectdictionary as od
+from canopen.variable import Variable
+
+
+class _StubVariable(Variable):
+    """Minimal concrete Variable for testing read/write/bits."""
+
+    def __init__(self, od_var):
+        super().__init__(od_var)
+        self._data = od_var.encode_raw(od_var.default)
+
+    def get_data(self):
+        return self._data
+
+    def set_data(self, data):
+        self._data = data
+
+
+class TestVariable(unittest.TestCase):
+
+    def test_read_invalid_format(self):
+        var = od.ODVariable("Test UNSIGNED8", 0x1000)
+        var.data_type = od.UNSIGNED8
+        var.default = 0
+        v = _StubVariable(var)
+        with self.assertRaises(ValueError):
+            v.read(fmt="invalid")
+
+    def test_write_desc(self):
+        var = od.ODVariable("Test UNSIGNED8", 0x1000)
+        var.data_type = od.UNSIGNED8
+        var.default = 0
+        var.add_value_description(0, "Off")
+        var.add_value_description(1, "On")
+        v = _StubVariable(var)
+        v.write("On", fmt="desc")
+        self.assertEqual(v.raw, 1)
+
+    def test_raw_with_string_value(self):
+        var = od.ODVariable("Test VISIBLE_STRING", 0x1000)
+        var.data_type = od.VISIBLE_STRING
+        var.default = "hello"
+        var.add_value_description(0, "Off")
+        v = _StubVariable(var)
+        # String value must not be looked up in value_descriptions
+        self.assertEqual(v.raw, "hello")
+
+    def test_bits(self):
+        var = od.ODVariable("Test UNSIGNED8", 0x1000)
+        var.data_type = od.UNSIGNED8
+        var.default = 0
+        var.add_bit_definition("BIT 0", [0])
+        var.add_bit_definition("BIT 2 and 3", [2, 3])
+        v = _StubVariable(var)
+        v.raw = 5
+        bits = v.bits
+        self.assertEqual(bits[0], 1)
+        bits[0] = 0
+        self.assertEqual(v.raw, 4)
+
+
+if __name__ == "__main__":
+    unittest.main()

From e592546b045b95e5c321f404787308736cc7ea16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Colomb?= <src@andre.colomb.de>
Date: Tue, 5 May 2026 22:24:40 +0200
Subject: [PATCH 2/2] Raise ValueError on invalid fmt argument.

---
 canopen/variable.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/canopen/variable.py b/canopen/variable.py
index d2538c3f..639a1839 100644
--- a/canopen/variable.py
+++ b/canopen/variable.py
@@ -135,6 +135,7 @@ def read(self, fmt: str = "raw") -> Union[int, bool, float, str, bytes]:
 
         :returns:
             The value of the variable.
+        :raises ValueError: For unsupported fmt values.
         """
         if fmt == "raw":
             return self.raw
@@ -142,6 +143,7 @@ def read(self, fmt: str = "raw") -> Union[int, bool, float, str, bytes]:
             return self.phys
         elif fmt == "desc":
             return self.desc
+        raise ValueError(f"Invalid format '{fmt}'")
 
     def write(
         self, value: Union[int, bool, float, str, bytes], fmt: str = "raw"