move provider from ctor dep to method argument at ChargeCalculator.charge

Author: kaiosilveira

src/charge-calculator/index.js

@@ -1,10 +1,8 @@
 export class ChargeCalculator {
-  constructor(provider) {
-    this._provider = provider;
-  }
+  constructor() {}
 
-  charge(customer, usage) {
+  charge(customer, usage, provider) {
     const baseCharge = customer.baseRate * usage;
-    return baseCharge + this._provider.connectionCharge;
+    return baseCharge + provider.connectionCharge;
   }
 }

src/charge-calculator/index.test.js

@@ -6,8 +6,8 @@ describe('ChargeCalculator', () => {
     const customer = { baseRate: 10 };
     const provider = { connectionCharge: 5 };
 
-    const chargeCalculator = new ChargeCalculator(provider);
+    const chargeCalculator = new ChargeCalculator();
 
-    expect(chargeCalculator.charge(customer, usage)).toBe(1005);
+    expect(chargeCalculator.charge(customer, usage, provider)).toBe(1005);
   });
 });

src/index.js

@@ -6,5 +6,5 @@ export function calculateMonthCharge(customer, usage, provider) {
 }
 
 function charge(customer, usage, provider) {
-  return new ChargeCalculator(provider).charge(customer, usage);
+  return new ChargeCalculator().charge(customer, usage, provider);
 }