Add Jest testing for useImperialConfig.ts

useImperialConfig.ts
- Added exports to the pure functions to get them inside the test file

useImperialConfig.test.ts
- Added a Jest mock to mock the useAppConfig
- Tested use cases for the 4 functions

www/__tests__/useImperialConfig.test.ts

@@ -0,0 +1,80 @@
+import { getFormattedDistanceInKm, getFormattedDistanceInMiles, getKmph, getMph } 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: {
+      use_imperial: false
+    },
+    loading: false
+  }));
+});
+
+
+describe('getFormattedDistanceInKm', () => {
+  it('should format distance in kilometers', () => {
+    expect(getFormattedDistanceInKm('1000')).toBe('1.00');
+    expect(getFormattedDistanceInKm('1500')).toBe('1.50');
+    expect(getFormattedDistanceInKm('500')).toBe('0.50');
+    expect(getFormattedDistanceInKm('0')).toBe('0.0');
+  });
+
+  it('returns NaN for an empty input', () => {
+    expect(getFormattedDistanceInKm('')).toBe('NaN');
+  });
+
+  it('returns NaN for a non-numeric input', () => {
+    expect(getFormattedDistanceInKm('abc')).toBe('NaN');
+  });
+});
+
+describe('getFormattedDistanceInMiles', () => {
+  it('should format distance in miles', () => {
+    expect(getFormattedDistanceInMiles('1609.34')).toBe('1.0');
+    expect(getFormattedDistanceInMiles('3218.68')).toBe('2.00');
+    expect(getFormattedDistanceInMiles('804.672')).toBe('0.50');
+    expect(getFormattedDistanceInKm('0')).toBe('0.0');
+  });
+
+  it('returns NaN for an empty input', () => {
+    expect(getFormattedDistanceInMiles('')).toBe('NaN');
+  });
+
+  it('returns NaN for a non-numeric input', () => {
+    expect(getFormattedDistanceInMiles('abc')).toBe('NaN');
+  });
+});
+
+describe('getKmph', () => {
+  it('should convert meters per second to kilometers per hour', () => {
+    expect(getKmph('10')).toBe('36.00');
+    expect(getKmph('20')).toBe('72.00');
+    expect(getKmph('5')).toBe('18.00');
+    expect(getKmph('30.0')).toBe('108.00');
+  });
+
+  it('returns 0.00 for an empty input', () => {
+    expect(getKmph('')).toBe('0.00');
+  });
+
+  it('returns NaN for a non-numeric input', () => {
+    expect(getKmph('abc')).toBe('NaN');
+  });
+});
+
+describe('getMph', () => {
+  it('should convert meters per second to miles per hour', () => {
+    expect(getMph('10')).toBe('22.37');
+    expect(getMph('20')).toBe('44.74');
+    expect(getMph('5')).toBe('11.18');
+  });
+
+  it('returns 0.00 for an empty input', () => {
+    expect(getMph('')).toBe('0.00');
+  });
+
+  it('returns NaN for a non-numeric input', () => {
+    expect(getMph('abc')).toBe('NaN');
+  });
+});

www/js/config/useImperialConfig.ts

@@ -17,16 +17,16 @@ const formatDistance = (dist: number) => {
   return Math.round(dist).toString();
 }
 
-const getFormattedDistanceInKm = (distInMeters: string) =>
+export const getFormattedDistanceInKm = (distInMeters: string) =>
   formatDistance(Number.parseFloat(distInMeters) / 1000);
 
-const getFormattedDistanceInMiles = (distInMeters: string) =>
+export const getFormattedDistanceInMiles = (distInMeters: string) =>
   formatDistance((Number.parseFloat(distInMeters) / 1000) * KM_TO_MILES);
 
-const getKmph = (metersPerSec) =>
+export const getKmph = (metersPerSec) =>
   (metersPerSec * 3.6).toFixed(2);
 
-const getMph = (metersPerSecond) =>
+export const getMph = (metersPerSecond) =>
   (KM_TO_MILES * Number.parseFloat(getKmph(metersPerSecond))).toFixed(2);
 
 export function useImperialConfig() {