Validate that a given campaign config has an iteration staring on or before the campaign itself.

Author: acerathereinspirative-nhs-nvir

src/eligibility_signposting_api/model/rules.py

@@ -147,7 +147,7 @@ class CampaignConfig(BaseModel):
     end_date: EndDate = Field(..., alias="EndDate")
     approval_minimum: int | None = Field(None, alias="ApprovalMinimum")
     approval_maximum: int | None = Field(None, alias="ApprovalMaximum")
-    iterations: list[Iteration] = Field(..., alias="Iterations")
+    iterations: list[Iteration] = Field(..., min_length=1, alias="Iterations")
 
     model_config = {"populate_by_name": True, "arbitrary_types_allowed": True, "extra": "ignore"}
 
@@ -172,16 +172,31 @@ def check_no_overlapping_iterations(self) -> typing.Self:
             raise ValueError(message)
         return self
 
+    @model_validator(mode="after")
+    def check_has_iteration_from_start(self) -> typing.Self:
+        iterations_by_date = sorted(self.iterations, key=attrgetter("iteration_date"))
+        if first_iteration := next(iter(iterations_by_date), None):
+            if first_iteration.iteration_date > self.start_date:
+                message = (
+                    f"campaign {self.id} starts on {self.start_date}, "
+                    f"1st iteration starts later - {first_iteration.iteration_date}"
+                )
+                raise ValueError(message)
+            return self
+        # Should never happen, since we are constraining self.iterations with a min_length of 1
+        message = f"campaign {self.id} has no iterations."
+        raise ValueError(message)
+
     @cached_property
     def campaign_live(self) -> bool:
         today = datetime.now(tz=UTC).date()
         return self.start_date <= today <= self.end_date
 
     @cached_property
-    def current_iteration(self) -> Iteration | None:
+    def current_iteration(self) -> Iteration:
         today = datetime.now(tz=UTC).date()
         iterations_by_date_descending = sorted(self.iterations, key=attrgetter("iteration_date"), reverse=True)
-        return next((i for i in iterations_by_date_descending if i.iteration_date <= today), None)
+        return next(i for i in iterations_by_date_descending if i.iteration_date <= today)
 
 
 class Rules(BaseModel):

src/eligibility_signposting_api/services/calculators/eligibility_calculator.py

@@ -32,7 +32,7 @@ class EligibilityCalculator:
 
     @property
     def active_campaigns(self) -> list[rules.CampaignConfig]:
-        return [cc for cc in self.campaign_configs if cc.campaign_live and cc.current_iteration]
+        return [cc for cc in self.campaign_configs if cc.campaign_live]
 
     @property
     def campaigns_grouped_by_condition_name(
@@ -71,11 +71,8 @@ def get_the_base_eligible_campaigns(self, campaign_group: list[rules.CampaignCon
             return base_eligible_campaigns
         return []
 
-    def check_base_eligibility(self, iteration: rules.Iteration | None) -> bool:
+    def check_base_eligibility(self, iteration: rules.Iteration) -> bool:
         """Return cohorts for which person is base eligible."""
-
-        if not iteration:
-            return False  # pragma: no cover
         iteration_cohorts: set[str] = {
             cohort.cohort_label for cohort in iteration.iteration_cohorts if cohort.cohort_label
         }
@@ -100,7 +97,7 @@ def evaluate_eligibility_by_iteration_rules(
 
         status_with_reasons: dict[eligibility.Status, list[eligibility.Reason]] = defaultdict()
 
-        for iteration in [cc.current_iteration for cc in campaign_group if cc.current_iteration]:
+        for iteration in [cc.current_iteration for cc in campaign_group]:
             # Until we see a worse status, we assume someone is actionable for this iteration.
             worst_status = eligibility.Status.actionable
             exclusion_reasons, actionable_reasons = [], []

tests/fixtures/builders/model/rule.py

@@ -1,4 +1,5 @@
 from datetime import UTC, date, datetime, timedelta
+from operator import attrgetter
 from random import randint
 
 from polyfactory import Use
@@ -27,13 +28,44 @@ class IterationFactory(ModelFactory[rules.Iteration]):
     iteration_date = Use(past_date)
 
 
-class CampaignConfigFactory(ModelFactory[rules.CampaignConfig]):
+class RawCampaignConfigFactory(ModelFactory[rules.CampaignConfig]):
     iterations = Use(IterationFactory.batch, size=2)
 
     start_date = Use(past_date)
     end_date = Use(future_date)
 
 
+class CampaignConfigFactory(RawCampaignConfigFactory):
+    @classmethod
+    def build(cls, **kwargs) -> rules.CampaignConfig:
+        """Ensure invariants are met:
+        * no iterations with duplicate iteration dates
+        * must have iteration active from campaign start date"""
+        processed_kwargs = cls.process_kwargs(**kwargs)
+        start_date: date = processed_kwargs["start_date"]
+        iterations: list[rules.Iteration] = processed_kwargs["iterations"]
+
+        CampaignConfigFactory.fix_iteration_date_invariants(iterations, start_date)
+
+        data = super().build(**processed_kwargs).dict()
+        return cls.__model__(**data)
+
+    @staticmethod
+    def fix_iteration_date_invariants(iterations: list[rules.Iteration], start_date: date) -> None:
+        iterations.sort(key=attrgetter("iteration_date"))
+        iterations[0].iteration_date = start_date
+
+        seen: set[date] = set()
+        previous: date = iterations[0].iteration_date
+        for iteration in iterations:
+            current = iteration.iteration_date if iteration.iteration_date >= previous else previous + timedelta(days=1)
+            while current in seen:
+                current += timedelta(days=1)
+            seen.add(current)
+            iteration.iteration_date = current
+            previous = current
+
+
 class PersonAgeSuppressionRuleFactory(IterationRuleFactory):
     type = rules.RuleType.suppression
     name = rules.RuleName("Exclude too young less than 75")

tests/unit/model/test_rules.py

@@ -1,19 +1,34 @@
 import pytest
+from dateutil.relativedelta import relativedelta
 from faker import Faker
 
-from tests.fixtures.builders.model.rule import CampaignConfigFactory, IterationFactory
+from tests.fixtures.builders.model.rule import IterationFactory, RawCampaignConfigFactory
 
 
 def test_iteration_with_overlapping_start_dates_not_allowed(faker: Faker):
     # Given
-    iteration_date = faker.date("%Y%m%d")
-    iteration1 = IterationFactory.build(iteration_date=iteration_date)
-    iteration2 = IterationFactory.build(iteration_date=iteration_date)
+    start_date = faker.date_object()
+    iteration1 = IterationFactory.build(iteration_date=start_date)
+    iteration2 = IterationFactory.build(iteration_date=start_date)
 
     # When, Then
     with pytest.raises(
         ValueError,
         match=r"1 validation error for CampaignConfig\n"
         r".*2 iterations with iteration date",
     ):
-        CampaignConfigFactory.build(iterations=[iteration1, iteration2])
+        RawCampaignConfigFactory.build(start_date=start_date, iterations=[iteration1, iteration2])
+
+
+def test_iteration_must_have_active_iteration_from_its_start(faker: Faker):
+    # Given
+    start_date = faker.date_object()
+    iteration = IterationFactory.build(iteration_date=start_date + relativedelta(days=1))
+
+    # When, Then
+    with pytest.raises(
+        ValueError,
+        match=r"1 validation error for CampaignConfig\n"
+        r".*1st iteration starts later",
+    ):
+        RawCampaignConfigFactory.build(start_date=start_date, iterations=[iteration])

tests/unit/services/calculators/test_eligibility_calculator.py

@@ -3,7 +3,7 @@
 import pytest
 from faker import Faker
 from freezegun import freeze_time
-from hamcrest import assert_that, contains_exactly, empty, has_item, has_items
+from hamcrest import assert_that, contains_exactly, has_item, has_items
 
 from eligibility_signposting_api.model import rules
 from eligibility_signposting_api.model import rules as rules_model
@@ -247,32 +247,6 @@ def test_simple_rule_only_excludes_from_live_iteration(faker: Faker):
     )
 
 
-@freeze_time("2025-04-25")
-def test_campaign_with_no_active_iteration_not_considered(faker: Faker):
-    # Given
-    nhs_number = NHSNumber(faker.nhs_number())
-
-    person_rows = person_rows_builder(nhs_number)
-    campaign_configs = [
-        rule_builder.CampaignConfigFactory.build(
-            target="RSV",
-            iterations=[
-                rule_builder.IterationFactory.build(
-                    iteration_date=rules_model.IterationDate(datetime.date(2025, 4, 26)),
-                )
-            ],
-        )
-    ]
-
-    calculator = EligibilityCalculator(person_rows, campaign_configs)
-
-    # When
-    actual = calculator.evaluate_eligibility()
-
-    # Then
-    assert_that(actual, is_eligibility_status().with_conditions(empty()))
-
-
 @pytest.mark.parametrize(
     ("rule_type", "expected_status"),
     [