inline taxableChargeFn at taxableCharge getter

Author: kaiosilveira

src/reading/index.js

@@ -1,4 +1,4 @@
-const { baseRate, taxableChargeFn } = require('../tax-utils');
+const { baseRate, taxThreshold } = require('../tax-utils');
 
 class Reading {
   constructor(data) {
@@ -29,7 +29,7 @@ class Reading {
   }
 
   get taxableCharge() {
-    return taxableChargeFn(this);
+    return Math.max(0, this.baseCharge - taxThreshold(this.year));
   }
 }
 

src/reading/index.test.js

@@ -28,12 +28,13 @@ describe('Reading', () => {
 
   describe('taxableCharge', () => {
     it('should calculate the correct taxable charge', () => {
-      jest.spyOn(TaxUtils, 'taxableChargeFn').mockReturnValue(0.5);
+      jest.spyOn(TaxUtils, 'taxThreshold').mockReturnValue(1);
+      jest.spyOn(TaxUtils, 'baseRate').mockReturnValue(1);
 
       const rawData = { customer: 'Ivan', quantity: 10, month: 5, year: 2017 };
       const reading = new Reading(rawData);
 
-      expect(reading.taxableCharge).toEqual(0.5);
+      expect(reading.taxableCharge).toEqual(9);
     });
   });
 });