Add error handling for mid-parental-height functions

rcpchgrowth/constants/validation_constants.py

@@ -47,6 +47,12 @@
 # lower limit to paternal and maternal height here therefore set arbitrarily at 50 cm
 # (this constant was added from the API server `schemas/request_validation_classes.py`)
 
+MAXIMUM_PARENTAL_HEIGHT_CM = 260
+# The tallest person for whom there is irrefutable evidence is
+# Robert Pershing Wadlow who was 2.72m (272 cm) tall at his death in 1940
+# https://en.wikipedia.org/wiki/Robert_Wadlow
+# Setting maximum at 260 cm to allow for measurement errors while still catching impossible values
+
 # These constants are used to determine the range of SDS values that are considered - see discussion in issue #32 in the rcpchgrowth-python repository
 # All previous hard-coded values have been replaced with these constants
 MINIMUM_HEIGHT_WEIGHT_OFC_ADVISORY_SDS = -4

rcpchgrowth/mid_parental_height.py

@@ -1,4 +1,4 @@
-from .constants import HEIGHT, MALE, FEMALE, UK_WHO, WHO
+from .constants import HEIGHT, MALE, FEMALE, UK_WHO, WHO, MINIMUM_PARENTAL_HEIGHT_CM, MAXIMUM_PARENTAL_HEIGHT_CM, REFERENCES, SEXES
 from .global_functions import sds_for_measurement
 """
 Functions to calculate mid-parental height
@@ -11,7 +11,37 @@
 def mid_parental_height(maternal_height, paternal_height, sex):
     """
     Calculate mid-parental height
+
+    maternal_height: Maternal height in cm (float)
+    paternal_height: Paternal height in cm (float)
+    sex: Sex of the child ('male' or 'female')
+    return: Mid-parental height in cm (float)
+    raises ValueError: If any input is invalid
     """
+    # Validate sex
+    if sex not in SEXES:
+        raise ValueError(f"Sex must be '{MALE}' or '{FEMALE}', got '{sex}'")
+
+    # Validate maternal_height
+    if maternal_height is None:
+        raise ValueError("Maternal height cannot be None. Please provide a height in cm.")
+    if not isinstance(maternal_height, (int, float)):
+        raise ValueError(f"Maternal height must be a number, got {type(maternal_height).__name__}")
+    if maternal_height < MINIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Maternal height of {maternal_height} cm is below the minimum of {MINIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+    if maternal_height > MAXIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Maternal height of {maternal_height} cm is above the maximum of {MAXIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+
+    # Validate paternal_height
+    if paternal_height is None:
+        raise ValueError("Paternal height cannot be None. Please provide a height in cm.")
+    if not isinstance(paternal_height, (int, float)):
+        raise ValueError(f"Paternal height must be a number, got {type(paternal_height).__name__}")
+    if paternal_height < MINIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Paternal height of {paternal_height} cm is below the minimum of {MINIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+    if paternal_height > MAXIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Paternal height of {paternal_height} cm is above the maximum of {MAXIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+
     if sex == MALE:
         return (maternal_height + paternal_height + 13) / 2
     else:
@@ -20,7 +50,36 @@ def mid_parental_height(maternal_height, paternal_height, sex):
 def mid_parental_height_z(maternal_height, paternal_height, reference=UK_WHO):
     """
     Calculate mid-parental height standard deviation
+
+    :param maternal_height: Maternal height in cm (float)
+    :param paternal_height: Paternal height in cm (float)
+    :param reference: Reference dataset to use (default: 'uk-who')
+    :return: Mid-parental height z-score (float)
+    :raises ValueError: If any input is invalid
     """
+    # Validate reference
+    if reference not in REFERENCES:
+        raise ValueError(f"Reference must be one of {REFERENCES}, got '{reference}'")
+
+    # Validate maternal_height
+    if maternal_height is None:
+        raise ValueError("Maternal height cannot be None. Please provide a height in cm.")
+    if not isinstance(maternal_height, (int, float)):
+        raise ValueError(f"Maternal height must be a number, got {type(maternal_height).__name__}")
+    if maternal_height < MINIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Maternal height of {maternal_height} cm is below the minimum of {MINIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+    if maternal_height > MAXIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Maternal height of {maternal_height} cm is above the maximum of {MAXIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+
+    # Validate paternal_height
+    if paternal_height is None:
+        raise ValueError("Paternal height cannot be None. Please provide a height in cm.")
+    if not isinstance(paternal_height, (int, float)):
+        raise ValueError(f"Paternal height must be a number, got {type(paternal_height).__name__}")
+    if paternal_height < MINIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Paternal height of {paternal_height} cm is below the minimum of {MINIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
+    if paternal_height > MAXIMUM_PARENTAL_HEIGHT_CM:
+        raise ValueError(f"Paternal height of {paternal_height} cm is above the maximum of {MAXIMUM_PARENTAL_HEIGHT_CM} cm and is considered to be an error.")
 
     # convert parental heights to z-scores
     adult_age = 20.0

rcpchgrowth/tests/test_mid_parental_height.py

@@ -1,6 +1,6 @@
 import pytest
 
-from rcpchgrowth.constants import MALE, FEMALE, UK_WHO, CDC
+from rcpchgrowth.constants import MALE, FEMALE, UK_WHO, CDC, MINIMUM_PARENTAL_HEIGHT_CM, MAXIMUM_PARENTAL_HEIGHT_CM
 from rcpchgrowth.mid_parental_height import mid_parental_height, mid_parental_height_z, expected_height_z_from_mid_parental_height_z
 
 maternal_height = 151
@@ -13,4 +13,105 @@ def test_midparental_height():
     assert mid_parental_height(maternal_height=maternal_height, paternal_height=paternal_height, sex=FEMALE) == 152.5
     assert mid_parental_height_z(maternal_height=maternal_height, paternal_height=paternal_height, reference=UK_WHO) == pytest.approx(-0.8943229, ACCURACY)
     assert mid_parental_height_z(maternal_height=maternal_height, paternal_height=paternal_height, reference=CDC) == pytest.approx(-0.8177165233046019, ACCURACY)
-    assert expected_height_z_from_mid_parental_height_z(mid_parental_height_z=-0.8943229) == pytest.approx(-0.44716145, ACCURACY)
+    assert expected_height_z_from_mid_parental_height_z(mid_parental_height_z=-0.8943229) == pytest.approx(-0.44716145, ACCURACY)
+
+
+def test_midparental_height_validation_none_values():
+    """Test that None values raise appropriate errors"""
+    with pytest.raises(ValueError, match="Maternal height cannot be None"):
+        mid_parental_height(maternal_height=None, paternal_height=paternal_height, sex=MALE)
+
+    with pytest.raises(ValueError, match="Paternal height cannot be None"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=None, sex=MALE)
+
+    with pytest.raises(ValueError, match="Maternal height cannot be None"):
+        mid_parental_height_z(maternal_height=None, paternal_height=paternal_height, reference=UK_WHO)
+
+    with pytest.raises(ValueError, match="Paternal height cannot be None"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height=None, reference=UK_WHO)
+
+
+def test_midparental_height_validation_non_numeric():
+    """Test that non-numeric values raise appropriate errors"""
+    with pytest.raises(ValueError, match="Maternal height must be a number"):
+        mid_parental_height(maternal_height="151", paternal_height=paternal_height, sex=MALE)
+
+    with pytest.raises(ValueError, match="Paternal height must be a number"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height="167", sex=MALE)
+
+    with pytest.raises(ValueError, match="Maternal height must be a number"):
+        mid_parental_height_z(maternal_height=[151], paternal_height=paternal_height, reference=UK_WHO)
+
+    with pytest.raises(ValueError, match="Paternal height must be a number"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height={"height": 167}, reference=UK_WHO)
+
+
+def test_midparental_height_validation_below_minimum():
+    """Test that heights below minimum raise appropriate errors"""
+    too_short = MINIMUM_PARENTAL_HEIGHT_CM - 1
+
+    with pytest.raises(ValueError, match=f"Maternal height of {too_short} cm is below the minimum"):
+        mid_parental_height(maternal_height=too_short, paternal_height=paternal_height, sex=MALE)
+
+    with pytest.raises(ValueError, match=f"Paternal height of {too_short} cm is below the minimum"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=too_short, sex=MALE)
+
+    with pytest.raises(ValueError, match=f"Maternal height of {too_short} cm is below the minimum"):
+        mid_parental_height_z(maternal_height=too_short, paternal_height=paternal_height, reference=UK_WHO)
+
+    with pytest.raises(ValueError, match=f"Paternal height of {too_short} cm is below the minimum"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height=too_short, reference=UK_WHO)
+
+
+def test_midparental_height_validation_above_maximum():
+    """Test that heights above maximum raise appropriate errors"""
+    too_tall = MAXIMUM_PARENTAL_HEIGHT_CM + 1
+
+    with pytest.raises(ValueError, match=f"Maternal height of {too_tall} cm is above the maximum"):
+        mid_parental_height(maternal_height=too_tall, paternal_height=paternal_height, sex=MALE)
+
+    with pytest.raises(ValueError, match=f"Paternal height of {too_tall} cm is above the maximum"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=too_tall, sex=MALE)
+
+    with pytest.raises(ValueError, match=f"Maternal height of {too_tall} cm is above the maximum"):
+        mid_parental_height_z(maternal_height=too_tall, paternal_height=paternal_height, reference=UK_WHO)
+
+    with pytest.raises(ValueError, match=f"Paternal height of {too_tall} cm is above the maximum"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height=too_tall, reference=UK_WHO)
+
+
+def test_midparental_height_validation_invalid_sex():
+    """Test that invalid sex values raise appropriate errors"""
+    with pytest.raises(ValueError, match="Sex must be 'male' or 'female'"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=paternal_height, sex="invalid")
+
+    with pytest.raises(ValueError, match="Sex must be 'male' or 'female'"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=paternal_height, sex="MALE")  # wrong case
+
+    with pytest.raises(ValueError, match="Sex must be 'male' or 'female'"):
+        mid_parental_height(maternal_height=maternal_height, paternal_height=paternal_height, sex=None)
+
+
+def test_midparental_height_z_validation_invalid_reference():
+    """Test that invalid reference values raise appropriate errors"""
+    with pytest.raises(ValueError, match="Reference must be one of"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height=paternal_height, reference="invalid")
+
+    with pytest.raises(ValueError, match="Reference must be one of"):
+        mid_parental_height_z(maternal_height=maternal_height, paternal_height=paternal_height, reference=None)
+
+
+def test_midparental_height_validation_boundary_values():
+    """Test that boundary values (minimum and maximum) are accepted"""
+    # Test minimum boundary
+    assert mid_parental_height(maternal_height=MINIMUM_PARENTAL_HEIGHT_CM, paternal_height=MINIMUM_PARENTAL_HEIGHT_CM, sex=MALE) == (MINIMUM_PARENTAL_HEIGHT_CM + MINIMUM_PARENTAL_HEIGHT_CM + 13) / 2
+
+    # Test maximum boundary
+    assert mid_parental_height(maternal_height=MAXIMUM_PARENTAL_HEIGHT_CM, paternal_height=MAXIMUM_PARENTAL_HEIGHT_CM, sex=FEMALE) == (MAXIMUM_PARENTAL_HEIGHT_CM + MAXIMUM_PARENTAL_HEIGHT_CM - 13) / 2
+
+    # Test that z-score calculation works with boundary values
+    result = mid_parental_height_z(maternal_height=MINIMUM_PARENTAL_HEIGHT_CM, paternal_height=MINIMUM_PARENTAL_HEIGHT_CM, reference=UK_WHO)
+    assert isinstance(result, float)
+
+    result = mid_parental_height_z(maternal_height=MAXIMUM_PARENTAL_HEIGHT_CM, paternal_height=MAXIMUM_PARENTAL_HEIGHT_CM, reference=UK_WHO)
+    assert isinstance(result, float)