Webinar

history/source/rates/RatesService.js

@@ -1,3 +1,6 @@
+/**
+ * This service returns historical exchange rates
+ */
 module.exports = class RatesService {
 
     constructor(repository) {
@@ -7,17 +10,14 @@ module.exports = class RatesService {
     loadRatesHistory(src, target) {
         const data =  this.repository.load(src + "_TO_" + target);
 
+        // Each data point in "data" follows this format:
+        //  { "value": exchangeRateValue }
+
         if (data === null) {
             throw new Error("Unknown currency conversion");
         }
 
-        return data.map((element, i) => {
-            const elementWithDate = {...element};
-            var date = new Date();
-            date.setDate(date.getDate() - i);
-            elementWithDate["date"] = date;
-            return elementWithDate;
-        });
+        return data.map(rate => ({ date: new Date() , ...rate }));
     }
 
 };

history/tests/unit/rates/RatesService.test.js

@@ -2,16 +2,6 @@ const RatesService = require("../../../source/rates/RatesService");
 
 describe("RatesService", () => {
 
-    // test("returns rates retrieved from a rates repository", () => {
-    //     const repository = {
-    //         load: () => [{ value: 1 }, { value: 2 }, { value: 3 } ]
-    //     };
-
-    //     const service = new RatesService(repository);
-    //     const rates = service.loadRatesHistory("EUR", "USD");
-    //     expect(rates).toEqual([{ value: 1 }, { value: 2 }, { value: 3 } ]);
-    // });
-
     test("throws an exception if the repository returns null", () => {
         function invalidScenario() {
             const repository = {
@@ -24,14 +14,33 @@ describe("RatesService", () => {
         expect(invalidScenario).toThrow(/Unknown currency conversion/i);
     });
 
-    test("returns a list of currency exchange rates with dates", () => {
+    test("returns exchange rates", () => {
+        // Given
         const repository = {
-            load: () => [{ value: 1 }, { value: 2 }, { value: 3 } ]
+            load: () => [{ value: 0.5}]
         };
+        const service = new RatesService(repository);
+
+        // When
+        const rates = service.loadRatesHistory("EUR", "USD");
+
+        // Then
+        expect(rates[0].value).toBe(0.5);
+    });
+
 
+    test("returns exchange rates including dates", () => {
+        // Given
+        const repository = {
+            load: () => [{ value: 0.5}, { value: 0.3 }]
+        };
         const service = new RatesService(repository);
+
+        // When
         const rates = service.loadRatesHistory("EUR", "USD");
-        for (const rate of rates) {
+
+        // Then
+        for(const rate of rates) {
             expect(rate.date).toBeInstanceOf(Date);
         }
     });