Add unit tests for Variable class (#656)

* Add unit tests for Variable class.
* Raise ValueError on invalid fmt argument.

Co-authored-by: Frieder Schüler <frieder.schueler@bizerba.com>

Author: acolomb

canopen/variable.py

@@ -135,13 +135,15 @@ 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
         elif fmt == "phys":
             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"

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):
 

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):
     """

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()