[test] add unit tests for fares helper functions

source/fares/unit.test.ts

@@ -0,0 +1,34 @@
+import { getFarePrice } from '~/fares/helpers.ts'
+import { type Fare } from '~/fares/types.ts'
+
+describe('getFarePrice', () => {
+  it('should return 0 if Fare price is null', () => {
+    const fare: Fare = {
+      day: '2023-09-01',
+      arrivalDate: '2023-09-01T12:40:00',
+      departureDate: '2023-09-01T11:15:00',
+      price: null,
+      soldOut: false,
+      unavailable: false
+    }
+    expect(getFarePrice(fare)).toBe(0)
+  })
+
+  it('should return Fare price if not null', () => {
+    const fare: Fare = {
+      day: '2023-09-01',
+      arrivalDate: '2023-09-01T12:40:00',
+      departureDate: '2023-09-01T11:15:00',
+      price: {
+        value: 56.12,
+        valueMainUnit: '56',
+        valueFractionalUnit: '12',
+        currencyCode: 'EUR',
+        currencySymbol: '€'
+      },
+      soldOut: false,
+      unavailable: false
+    }
+    expect(getFarePrice(fare)).toBe(56.12)
+  })
+})