Merge pull request #1564 from PolicyEngine/codex/fix-1178

Fix state pension relative reform path

Author: MaxGhenis

changelog.d/state-pension-relative-reform.fixed.md

@@ -0,0 +1 @@
+Fixed `gov.contrib.cec.state_pension_increase` so state pension reforms affect microsimulation outputs and budget impacts.

policyengine_uk/tests/microsimulation/test_state_pension_reform.py

@@ -23,10 +23,27 @@ def reform_halved():
     )
 
 
+@pytest.fixture(scope="module")
+def reform_relative_cut():
+    return Microsimulation(reform={"gov.contrib.cec.state_pension_increase": -0.1})
+
+
 @pytest.mark.microsimulation
 def test_basic_state_pension_responds_to_reform(baseline, reform_halved):
     baseline_total = baseline.calculate("basic_state_pension", YEAR).sum()
     reform_total = reform_halved.calculate("basic_state_pension", YEAR).sum()
 
     assert baseline_total > 0
     assert reform_total < baseline_total * 0.9
+
+
+@pytest.mark.microsimulation
+def test_relative_state_pension_reform_affects_budget(baseline, reform_relative_cut):
+    baseline_total = baseline.calculate("state_pension", YEAR).sum()
+    reform_total = reform_relative_cut.calculate("state_pension", YEAR).sum()
+    baseline_balance = baseline.calculate("gov_balance", YEAR).sum()
+    reform_balance = reform_relative_cut.calculate("gov_balance", YEAR).sum()
+
+    assert baseline_total > 0
+    assert reform_total < baseline_total * 0.95
+    assert reform_balance > baseline_balance

policyengine_uk/variables/input/state_pension.py

@@ -12,20 +12,19 @@ class state_pension(Variable):
     uprating = "gov.economic_assumptions.indices.obr.consumer_price_index"
 
     def formula(person, period, parameters):
-        gov = parameters(period).gov
-        if gov.contrib.abolish_state_pension:
+        contrib = parameters.gov.contrib
+        if contrib.abolish_state_pension(period):
             return 0
-        relative_increase = gov.contrib.cec.state_pension_increase
-        uprating = 1 + relative_increase
-        sp = gov.dwp.state_pension
-        gender = person("gender", period).decode_to_str()
-        is_sp_age = person("is_SP_age", period)
-        return add(
-            person,
-            period,
-            [
-                "basic_state_pension",
-                "additional_state_pension",
-                "new_state_pension",
-            ],
+        uprating = 1 + contrib.cec.state_pension_increase(period)
+        return (
+            add(
+                person,
+                period,
+                [
+                    "basic_state_pension",
+                    "additional_state_pension",
+                    "new_state_pension",
+                ],
+            )
+            * uprating
         )