Esercitazione Fabrizio

lib/string-calculator.js

@@ -1,4 +1,26 @@
-exports.add = function (string) {
-  let numbers = string.split(/,|\n/).map(Number)
-  return numbers.reduce((a, b) => a + b)
+module.exports = { add, parseCustomDelimiter }
+
+function add (string) {
+  if (string.length === 0) {
+    return 0
+  }
+  let customDelimiter = parseCustomDelimiter(string)
+  let sum = 0
+  let numbers
+  if (customDelimiter) {
+    string = string.substr(3, string.length)
+    numbers = string.split(customDelimiter)
+  } else {
+    numbers = string.split(/,|\n/g)
+  }
+  for (let i = 0; i < numbers.length; i++) {
+    sum += parseInt(numbers[i])
+  }
+  return sum
+}
+
+function parseCustomDelimiter (string) {
+  if (string.length > 2 && string[0] === '/' && string[1] === '/') {
+    return string[2]
+  }
 }

test/string-calculator-test.js

@@ -1,22 +1,45 @@
-const assert = require('assert')
-const calculator = require('../lib/string-calculator')
+const {equal} = require('assert')
 
-describe('string-calculator', function () {
-  describe('add', function () {
-    it('is 0 for an empty string', function () {
-      assert.equal(calculator.add(''), 0)
+describe('StringCalculator', function () {
+  const StringCalculator = require('../lib/string-calculator')
+
+  describe('#add', function () {
+    const {add} = StringCalculator
+
+    it('returns 0 on empty string', function () {
+      equal(add(''), 0)
+    })
+
+    it('returns number for a single number string', function () {
+      equal(add('1'), 1)
+    })
+
+    it('returns sum for a comma separated string with two values', function () {
+      equal(add('1,2'), 3)
     })
 
-    it('is a number for a string with only a number', function () {
-      assert.equal(calculator.add('1'), 1)
+    it('returns sum for an unknown number of comma separated values', function () {
+      equal(add('1,2,3,4'), 10)
     })
 
-    it('is the sum of the numbers for a string of any amount of comma-separated numbers', function () {
-      assert.equal(calculator.add('1,2,3'), 6)
+    it('returns sum for an unknown number of an end-of-line separated values', function () {
+      equal(add('1\n2'), 3)
+    })
+
+    it('returns sum for custom delimited values', function () {
+      equal(add('//x\n1x2'), 3)
+    })
+  })
+
+  describe('#parseCustomDelimiter', function () {
+    const {parseCustomDelimiter: parse} = StringCalculator
+
+    it('returns undefined if no custom delimiter is specified', function () {
+      equal(parse('1,2'), undefined)
     })
 
-    it('handles also \\n as number delimiter', function () {
-      assert.equal(calculator.add('1\n2'), 3)
+    it('returns a custom delimiter', function () {
+      equal(parse('//x\n1x2'), 'x')
     })
   })
 })