Add personal history of cancer to PLCO calculator

Author: Themitchell

lung_cancer_screening/calculators/plco.py

@@ -8,11 +8,13 @@ class Plco:
     BMI_COEFFICIENT = Decimal('-0.0274194')
     BMI_CENTRED_OR_REFERENT_REF_GROUP = Decimal('27')
     COPD_ENPHYSEMA_OR_CHRONIC_BRONCHITIS_COEFFICIENT = Decimal('0.3553063')
+    PERSONAL_HISTORY_OF_CANCER_COEFFICIENT = Decimal('0.4589971')
 
-    def __init__(self, age=None, bmi=None, copd_enphysema_or_chronic_bronchitis=None):
+    def __init__(self, age=None, bmi=None, copd_enphysema_or_chronic_bronchitis=None, personal_history_of_cancer=None):
         self.age = Decimal(str(age or 0))
         self.bmi = Decimal(str(bmi or 0))
         self.copd_enphysema_or_chronic_bronchitis = copd_enphysema_or_chronic_bronchitis
+        self.personal_history_of_cancer = personal_history_of_cancer
 
     def age_in_years_contribution_to_estimate(self):
         return (self.age - self.AGE_CENTRED_OR_REFERENT_REF_GROUP) * self.AGE_COEFFICIENT
@@ -27,5 +29,13 @@ def copd_enphysema_or_chronic_bronchitis_contribution_to_estimate(self):
 
         return self.copd_enphysema_or_chronic_bronchitis * self.COPD_ENPHYSEMA_OR_CHRONIC_BRONCHITIS_COEFFICIENT
 
+
+    def personal_history_of_cancer_contribution_to_estimate(self):
+        if self.personal_history_of_cancer is None:
+            raise self.InvalidValueError(
+                "personal_history_of_cancer must be true or false")
+
+        return self.personal_history_of_cancer * self.PERSONAL_HISTORY_OF_CANCER_COEFFICIENT
+
     class InvalidValueError(Exception):
         pass

lung_cancer_screening/calculators/tests/test_plco.py

@@ -61,3 +61,25 @@ def test_copd_enphysema_or_chronic_bronchitiscontribution_to_estimate_when_false
         result = calculator.copd_enphysema_or_chronic_bronchitis_contribution_to_estimate()
 
         self.assertEqual(result, Decimal('0'))
+
+    def test_personal_history_of_cancer_contribution_to_estimate_when_none(self):
+        calculator = Plco(personal_history_of_cancer=None)
+
+        self.assertRaises(
+            Plco.InvalidValueError,
+            calculator.personal_history_of_cancer_contribution_to_estimate
+        )
+
+    def test_personal_history_of_cancer_contribution_to_estimate_when_true(self):
+        calculator = Plco(personal_history_of_cancer=True)
+
+        result = calculator.personal_history_of_cancer_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0.4589971'))
+
+    def test_personal_history_of_cancer_contribution_to_estimate_when_false(self):
+        calculator = Plco(personal_history_of_cancer=False)
+
+        result = calculator.personal_history_of_cancer_contribution_to_estimate()
+
+        self.assertEqual(result, Decimal('0'))