LGTM

frontend/src/lib/api.test.ts

@@ -4,6 +4,12 @@ import type { FeatureMeta } from '../types';
 import { apiUrl, assertOk, buildFilterString, isAbortError } from './api';
 import { createSchoolFilterKey } from './school-filter';
 import { createSpecificCrimeFilterKey } from './crime-filter';
+import { createEthnicityFilterKey } from './ethnicity-filter';
+import {
+  POI_COUNT_2KM_FILTER_NAME,
+  createPoiDistanceFilterKey,
+  createPoiFilterKey,
+} from './poi-distance-filter';
 
 describe('api utilities', () => {
   it('builds API URLs from endpoint names, paths, and params', () => {
@@ -99,4 +105,52 @@ describe('api utilities', () => {
       )
     ).toBe('Burglary (avg/yr):0:5;;Vehicle crime (avg/yr):1:10');
   });
+
+  it('deduplicates repeated ethnicity filters to the strictest backend range', () => {
+    const features: FeatureMeta[] = [{ name: '% White', type: 'numeric', min: 0, max: 100 }];
+
+    expect(
+      buildFilterString(
+        {
+          [createEthnicityFilterKey('% White', 1)]: [10, 90],
+          [createEthnicityFilterKey('% White', 2)]: [20, 80],
+        },
+        features
+      )
+    ).toBe('% White:20:80');
+  });
+
+  it('serializes POI distance filters using their selected backend feature', () => {
+    const features: FeatureMeta[] = [
+      { name: 'Distance to nearest park (km)', type: 'numeric', min: 0, max: 2 },
+      { name: 'Distance to nearest Tesco (km)', type: 'numeric', min: 0, max: 5 },
+    ];
+
+    expect(
+      buildFilterString(
+        {
+          [createPoiDistanceFilterKey('Distance to nearest park (km)', 1)]: [0, 0.5],
+          [createPoiDistanceFilterKey('Distance to nearest Tesco (km)', 2)]: [0, 1],
+        },
+        features
+      )
+    ).toBe('Distance to nearest park (km):0:0.5;;Distance to nearest Tesco (km):0:1');
+  });
+
+  it('serializes POI count filters using their selected backend feature', () => {
+    const features: FeatureMeta[] = [
+      { name: 'Number of Cafe POIs within 2km', type: 'numeric', min: 0, max: 20 },
+    ];
+
+    expect(
+      buildFilterString(
+        {
+          [createPoiFilterKey(POI_COUNT_2KM_FILTER_NAME, 'Number of Cafe POIs within 2km', 1)]: [
+            2, 10,
+          ],
+        },
+        features
+      )
+    ).toBe('Number of Cafe POIs within 2km:2:10');
+  });
 });