feat: add support for MHU sentence

pynmea2/types/talker.py

@@ -1130,4 +1130,13 @@ class MMB(TalkerSentence):
       ("UnitINHG", "unit_ingh"),
       ("PressureBars", "pressure_bars", float),
       ("UnitBars", "unit_bars")
-    )
+    )
+
+class MHU(TalkerSentence):
+    """Relative humidity."""
+    fields = (
+        ('Relative Humidity', 'relative_humidity', Decimal),
+        ('Absolute Humidity', 'absolute_humidity', Decimal),
+        ('Dew Point Temperature', 'dew_point_temperature', Decimal),
+        ('Temperature Unit', 'temperature_unit', str),
+    )

test/test_types.py

@@ -368,4 +368,37 @@ def test_MMB():
     assert msg.talker == 'WI'
     assert msg.sentence_type == 'MMB'
     assert msg.pressure_bars == 1004.6
-    assert msg.unit_bars == "B"
+    assert msg.unit_bars == "B"
+
+def test_MHU():
+    data = "$WIMHU,83.8,,,*53"
+    msg = pynmea2.parse(data)
+    assert msg.render() == data
+    assert msg.talker == 'WI'
+    assert msg.sentence_type == 'MHU'
+    assert msg.relative_humidity == Decimal('83.8')
+    assert msg.absolute_humidity is None
+    assert msg.dew_point_temperature is None
+    assert msg.temperature_unit is None
+
+def test_MHU_all_fields():
+    data = "$WIMHU,83.8,12.5,25.5,C*14"
+    msg = pynmea2.parse(data)
+    assert msg.render() == data
+    assert msg.talker == 'WI'
+    assert msg.sentence_type == 'MHU'
+    assert msg.relative_humidity == Decimal('83.8')
+    assert msg.absolute_humidity == Decimal('12.5')
+    assert msg.dew_point_temperature == Decimal('25.5')
+    assert msg.temperature_unit == 'C'
+
+def test_MHU_other_talker():
+    data = "$HCMHU,55.2,10.1,14.3,C*02"
+    msg = pynmea2.parse(data)
+    assert msg.render() == data
+    assert msg.talker == 'HC'
+    assert msg.sentence_type == 'MHU'
+    assert msg.relative_humidity == Decimal('55.2')
+    assert msg.absolute_humidity == Decimal('10.1')
+    assert msg.dew_point_temperature == Decimal('14.3')
+    assert msg.temperature_unit == 'C'