add useImperialConfig test

www/__tests__/useImperialConfig.test.ts

@@ -1,14 +1,22 @@
-import { convertDistance, convertSpeed, formatForDisplay } from '../js/config/useImperialConfig';
+import React from 'react';
+import {
+  convertDistance,
+  convertSpeed,
+  formatForDisplay,
+  useImperialConfig,
+} from '../js/config/useImperialConfig';
 
 // This mock is required, or else the test will dive into the import chain of useAppConfig.ts and fail when it gets to the root
 jest.mock('../js/useAppConfig', () => {
   return jest.fn(() => ({
-    appConfig: {
+    display_config: {
       use_imperial: false,
     },
     loading: false,
   }));
 });
+jest.spyOn(React, 'useState').mockImplementation((initialValue) => [initialValue, jest.fn()]);
+jest.spyOn(React, 'useEffect').mockImplementation((effect: () => void) => effect());
 
 describe('formatForDisplay', () => {
   it('should round to the nearest integer when value is >= 100', () => {
@@ -53,3 +61,15 @@ describe('convertSpeed', () => {
     expect(convertSpeed(6.7056, true)).toBeCloseTo(15); // Approximately 15 mph
   });
 });
+
+describe('useImperialConfig', () => {
+  it('returns ImperialConfig with imperial units', () => {
+    const imperialConfig = useImperialConfig();
+    expect(imperialConfig.distanceSuffix).toBe('km');
+    expect(imperialConfig.speedSuffix).toBe('kmph');
+    expect(imperialConfig.convertDistance(10)).toBe(0.01);
+    expect(imperialConfig.convertSpeed(20)).toBe(72);
+    expect(imperialConfig.getFormattedDistance(10)).toBe('0.01');
+    expect(imperialConfig.getFormattedSpeed(20)).toBe('72');
+  });
+});