feat(A-dmd): add getter to read current demand peak

also added valid tests

Signed-off-by: Milad Makdesi <milad@id8-engineering.io>

Author: MiladMakdesi

src/em511/em511.py

@@ -38,6 +38,7 @@ class Em511:
 
     EM511_REGISTER_V = 0x0
     EM511_REGISTER_A = 0x2
+    EM511_REGISTER_A_DMD = 0x3A
     EM511_REGISTER_W = 0x4
     EM511_REGISTER_W_DMD = 0xA
     EM511_REGISTER_W_DMD_PEAK = 0xC
@@ -175,6 +176,21 @@ def A(self) -> Decimal:
         value = Decimal(self._unpack(regs, self.EM511_REGISTER_A)) / self.SCALE_1000
         return round(value, 3)
 
+    @property
+    def A_dmd(self) -> Decimal:
+        """Current (A).
+
+        Returns:
+            Decimal: Current demand ampere value.
+
+        Raises:
+            ValueError: If input is at max value or above.
+            ModbusException: If failed to read input register.
+        """
+        regs = self._read_input_registers(self.EM511_REGISTER_A_DMD, self.INT32_REG_COUNT)
+        value = Decimal(self._unpack(regs, self.EM511_REGISTER_A_DMD)) / self.SCALE_1000
+        return round(value, 3)
+
     @property
     def W(self) -> Decimal:
         """Power (W).

src/em511/test_em511.py

@@ -75,6 +75,38 @@ def test_get_A() -> None:
         _ = meter.A
 
 
+def test_get_A_dmd() -> None:
+    """Test Get a_dmd."""
+    client = MagicMock()
+    mock_result = MagicMock()
+    mock_result.isError.return_value = False
+    meter = Em511(1, client)
+
+    """Test 1: should pass"""
+    mock_result.registers = [0x2904, 0x0000]
+    client.read_input_registers.return_value = mock_result
+    value = meter.A_dmd
+    assert value == Decimal("10.5")
+
+    """Test 2: Should pass."""
+    mock_result.registers = [0x1860, 0x0023]
+    client.read_input_registers.return_value = mock_result
+    value = meter.A_dmd
+    assert value == Decimal("2300.0")
+
+    """Test 3: Should raise exception due to more registers in use than allowed."""
+    mock_result.registers = [0x1860, 0x0023, 0x4244]
+    client.read_input_registers.return_value = mock_result
+    with pytest.raises(ValueError, match="Unexpected register count:"):
+        _ = meter.A_dmd
+
+    """Test 4: Should raise exception if input value exceeds maximum value, display shows 'EEE', 32-bit register."""
+    mock_result.registers = [0xFFFF, 0x7FFF]
+    client.read_input_registers.return_value = mock_result
+    with pytest.raises(ValueError, match="Input overflow EEE for 32-bit register: "):
+        _ = meter.A_dmd
+
+
 def test_get_W() -> None:
     """Test Get w."""
     client = MagicMock()