feat(tiered_pricing): 🔵 add tiers dependency in GraduatedTieredPricing

Author: adrianliz

exercises/graduated_tiered_prices/solutions/adrianliz/src/GraduatedTieredPricing.ts

@@ -2,7 +2,9 @@ import GraduatedTier from "./GraduatedTier";
 import Subscriptions from "./Subscriptions";
 
 export default class GraduatedTieredPricing {
-  private tiers(): GraduatedTier[] {
+  constructor(private readonly tiers: GraduatedTier[] | null) {}
+
+  private defaultTiers(): GraduatedTier[] {
     return [
       new GraduatedTier(1, 2, 299),
       new GraduatedTier(3, 10, 239),
@@ -13,6 +15,6 @@ export default class GraduatedTieredPricing {
   }
 
   priceFor(subscriptions: Subscriptions): number {
-    return subscriptions.priceFor(this.tiers());
+    return subscriptions.priceFor(this.tiers || this.defaultTiers());
   }
 }

exercises/graduated_tiered_prices/solutions/adrianliz/tests/GraduatedTieredPricing.test.ts

@@ -6,7 +6,7 @@ import Subscriptions from "../src/Subscriptions";
 
 describe("Graduated tiered pricing should", () => {
   it("throw number of subscriptions not allowed for 0 subscriptions", () => {
-    const pricing = new GraduatedTieredPricing();
+    const pricing = new GraduatedTieredPricing(null);
     expect(() => pricing.priceFor(new Subscriptions(0))).toThrow(
       NumberOfSubscriptionsNotAllowed
     );
@@ -23,7 +23,7 @@ describe("Graduated tiered pricing should", () => {
   ]).it(
     "calculate the price for %i subscriptions",
     (subscriptions: number, expectedPrice: number) => {
-      const pricing = new GraduatedTieredPricing();
+      const pricing = new GraduatedTieredPricing(null);
       expect(pricing.priceFor(new Subscriptions(subscriptions))).toBe(
         expectedPrice
       );