feat(dmd-integration-time): add getter to read demand integration time setting

also added valid tests

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

Author: MiladMakdesi

src/em511/em511.py

@@ -35,6 +35,8 @@ class Em511:
     STOP_BIT_MAX_VALUE = 1
     REPLY_DELAY_MIN_VALUE = 0
     REPLY_DELAY_MAX_VALUE = 1000
+    DMD_TIME_MIN_VALUE = 0
+    DMD_TIME_MAX_VALUE = 6
 
     EM511_REGISTER_V = 0x0
     EM511_REGISTER_A = 0x2
@@ -59,6 +61,7 @@ class Em511:
     EM511_REGISTER_RESET_PARTIAL_ENERGY_AND_HOUR_COUNTER = 0x4004
     EM511_REGISTER_RESET_DMD_AND_DMD_MAX = 0x4005
     EM511_REGISTER_RESET_TO_FACTORY_SETTINGS = 0x4020
+    EM511_REGISTER_DMD_INTEGRATION_TIME = 0x1010
 
     SCALE_10 = 10
     SCALE_100 = 100
@@ -365,6 +368,28 @@ def password(self) -> int:
             raise ValueError(msg)
         return value
 
+    @property
+    def dmd_integration_time(self) -> int:
+        """Demand integration time.
+
+        0=1min, 1=5min, 2=10min, 3=15min,
+        4=20min, 5=30min, 6=60min (default=3).
+
+        Returns:
+            int: Current demand integration time.
+
+        Raises:
+            ValueError: If input is at max value or above.
+            ValueError: If demand integration time is out of range.
+            ModbusException: If failed to read input register.
+        """
+        regs = self._read_input_registers(self.EM511_REGISTER_DMD_INTEGRATION_TIME, self.INT32_REG_COUNT)
+        value = self._unpack(regs, self.EM511_REGISTER_DMD_INTEGRATION_TIME)
+        if not (self.DMD_TIME_MIN_VALUE <= value <= self.DMD_TIME_MAX_VALUE):
+            msg = f"Invalid demand integration time value: {value}. Must be between 0 and 6."
+            raise ValueError(msg)
+        return value
+
     @property
     def device_id(self) -> int:
         """Device address.

src/em511/test_em511.py

@@ -453,6 +453,44 @@ def test_get_password() -> None:
         _ = meter.password
 
 
+def test_get_dmd_integration_time() -> None:
+    """Test Get dmd_integration_time."""
+    client = MagicMock()
+    mock_result = MagicMock()
+    mock_result.isError.return_value = False
+    meter = Em511(1, client)
+
+    """Test 1: should pass"""
+    mock_result.registers = [0x0006, 0x0000]
+    client.read_input_registers.return_value = mock_result
+    value = meter.dmd_integration_time
+    assert value == int("6")
+
+    """Test 2: Should pass."""
+    mock_result.registers = [0x0000, 0x0000]
+    client.read_input_registers.return_value = mock_result
+    value = meter.dmd_integration_time
+    assert value == int("0")
+
+    """Test 3: Should raise exception due to value not in range"""
+    mock_result.registers = [0x0007, 0x0000]
+    client.read_input_registers.return_value = mock_result
+    with pytest.raises(ValueError, match="Invalid demand integration time value: "):
+        _ = meter.dmd_integration_time
+
+    """Test 4: 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.dmd_integration_time
+
+    """Test 5: 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.dmd_integration_time
+
+
 def test_get_device_id() -> None:
     """Test Get device id/address."""
     client = MagicMock()