From 77c2c4bf267100fbd77dbb7f1e390ede67a253f1 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:10:02 +0100
Subject: [PATCH 01/11] handles empty string

---
 lib/string-calculator.js       |  5 ++---
 test/string-calculator-test.js | 24 +++++-------------------
 2 files changed, 7 insertions(+), 22 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 4e5388d..485150b 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -1,4 +1,3 @@
-exports.add = function (string) {
-  let numbers = string.split(/,|\n/).map(Number)
-  return numbers.reduce((a, b) => a + b)
+module.exports.add = function (string) {
+  return 0
 }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 281af1f..4281bb2 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -1,22 +1,8 @@
-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)
-    })
-
-    it('is a number for a string with only a number', function () {
-      assert.equal(calculator.add('1'), 1)
-    })
-
-    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('handles also \\n as number delimiter', function () {
-      assert.equal(calculator.add('1\n2'), 3)
-    })
+describe('StringCalculator', function () {
+  const StringCalculator = require('../lib/string-calculator')
+  it('returns 0 on empty string', function () {
+    equal(StringCalculator.add(''), 0)
   })
 })

From e21a69f9a370ffa4b6c0e8a793ee17eaa1ac759b Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:16:52 +0100
Subject: [PATCH 02/11] handles single value

---
 lib/string-calculator.js       | 3 +++
 test/string-calculator-test.js | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 485150b..9539306 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -1,3 +1,6 @@
 module.exports.add = function (string) {
+  if (string.length > 0) {
+    return parseInt(string)
+  }
   return 0
 }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 4281bb2..e76a573 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -5,4 +5,8 @@ describe('StringCalculator', function () {
   it('returns 0 on empty string', function () {
     equal(StringCalculator.add(''), 0)
   })
+
+  it('returns number for a single number string', function () {
+    equal(StringCalculator.add('1'), 1)
+  })
 })

From 85a8cda8fd72b5099c42482f36a36949c22c3319 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:23:05 +0100
Subject: [PATCH 03/11] handles two values

---
 lib/string-calculator.js       | 7 ++++++-
 test/string-calculator-test.js | 4 ++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 9539306..6f02c19 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -1,6 +1,11 @@
 module.exports.add = function (string) {
   if (string.length > 0) {
-    return parseInt(string)
+    if(string.indexOf(',') !== -1) {
+      let numbers = string.split(',')
+      return parseInt(numbers[0]) + parseInt(numbers[1])
+    } else {
+      return parseInt(string)
+    }
   }
   return 0
 }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index e76a573..cb626fb 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -9,4 +9,8 @@ describe('StringCalculator', function () {
   it('returns number for a single number string', function () {
     equal(StringCalculator.add('1'), 1)
   })
+
+  it('returns sum for a comma separated string with 2 values', function () {
+    equal(StringCalculator.add('1,2'), 3)
+  })
 })

From e7a50f060d5cd43e32170e641fc629ff98accbc5 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:25:31 +0100
Subject: [PATCH 04/11] refactoring

---
 lib/string-calculator.js | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 6f02c19..ab119bc 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -1,11 +1,11 @@
 module.exports.add = function (string) {
-  if (string.length > 0) {
-    if(string.indexOf(',') !== -1) {
-      let numbers = string.split(',')
-      return parseInt(numbers[0]) + parseInt(numbers[1])
-    } else {
-      return parseInt(string)
-    }
+  if (string.length === 0) {
+    return 0
+  }
+  if (string.indexOf(',') !== -1) {
+    let numbers = string.split(',')
+    return parseInt(numbers[0]) + parseInt(numbers[1])
+  } else {
+    return parseInt(string)
   }
-  return 0
 }

From 59e2a20c821e616bb6b6b75e13882c25e252ee95 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:32:40 +0100
Subject: [PATCH 05/11] sum an unknown number of comma separated values

---
 lib/string-calculator.js       | 7 +++++--
 test/string-calculator-test.js | 6 +++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index ab119bc..1879b1b 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -3,8 +3,11 @@ module.exports.add = function (string) {
     return 0
   }
   if (string.indexOf(',') !== -1) {
-    let numbers = string.split(',')
-    return parseInt(numbers[0]) + parseInt(numbers[1])
+    let sum = 0
+    for (let i = 0, numbers = string.split(','); i < numbers.length; i++) {
+      sum += parseInt(numbers[i])
+    }
+    return sum
   } else {
     return parseInt(string)
   }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index cb626fb..896a5c1 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -10,7 +10,11 @@ describe('StringCalculator', function () {
     equal(StringCalculator.add('1'), 1)
   })
 
-  it('returns sum for a comma separated string with 2 values', function () {
+  it('returns sum for a comma separated string with two values', function () {
     equal(StringCalculator.add('1,2'), 3)
   })
+
+  it('returns sum for an unknown number of comma separated values', function () {
+    equal(StringCalculator.add('1,2,3,4'), 10)
+  })
 })

From 15a776fe30c2ec14ab30e3cf94c4ec9965a8ce8b Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:38:44 +0100
Subject: [PATCH 06/11] handles new line delimiter

---
 lib/string-calculator.js       | 10 ++++++++--
 test/string-calculator-test.js |  4 ++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 1879b1b..b3f4b08 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -2,9 +2,15 @@ module.exports.add = function (string) {
   if (string.length === 0) {
     return 0
   }
-  if (string.indexOf(',') !== -1) {
+  var delimiter = ''
+  if(string.indexOf('\n') !== -1) {
+    delimiter = '\n'
+  } else {
+    delimiter = ','
+  }
+  if (delimiter !== '') {
     let sum = 0
-    for (let i = 0, numbers = string.split(','); i < numbers.length; i++) {
+    for (let i = 0, numbers = string.split(delimiter); i < numbers.length; i++) {
       sum += parseInt(numbers[i])
     }
     return sum
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 896a5c1..1b01a6e 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -17,4 +17,8 @@ describe('StringCalculator', function () {
   it('returns sum for an unknown number of comma separated values', function () {
     equal(StringCalculator.add('1,2,3,4'), 10)
   })
+
+  it('returns sum for an unknown number of an end-of-line separated values', function () {
+    equal(StringCalculator.add('1\n2'), 3)
+  })
 })

From a9076baf4280413e81a0e3a923cb0bf9ba28bcfc Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 17:49:44 +0100
Subject: [PATCH 07/11] refactoring handles new lines

---
 lib/string-calculator.js | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index b3f4b08..e422fcd 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -2,19 +2,10 @@ module.exports.add = function (string) {
   if (string.length === 0) {
     return 0
   }
-  var delimiter = ''
-  if(string.indexOf('\n') !== -1) {
-    delimiter = '\n'
-  } else {
-    delimiter = ','
-  }
-  if (delimiter !== '') {
-    let sum = 0
-    for (let i = 0, numbers = string.split(delimiter); i < numbers.length; i++) {
-      sum += parseInt(numbers[i])
-    }
-    return sum
-  } else {
-    return parseInt(string)
+  let sum = 0
+  let numbers = string.split(/,|\n/g)
+  for (let i = 0; i < numbers.length; i++) {
+    sum += parseInt(numbers[i])
   }
+  return sum
 }

From b44ad12ac598d97198a54c8a1c5efd9a520eaddc Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 18:07:52 +0100
Subject: [PATCH 08/11] added customDelimiterParser

---
 lib/string-calculator.js       |  9 +++++++
 test/string-calculator-test.js | 47 ++++++++++++++++++++++++----------
 2 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index e422fcd..b7d6391 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -2,6 +2,7 @@ module.exports.add = function (string) {
   if (string.length === 0) {
     return 0
   }
+  let customDelimiter = module.exports.parseCustomDelimiter(string)
   let sum = 0
   let numbers = string.split(/,|\n/g)
   for (let i = 0; i < numbers.length; i++) {
@@ -9,3 +10,11 @@ module.exports.add = function (string) {
   }
   return sum
 }
+
+ module.exports.parseCustomDelimiter = function (string) {
+   if(string.length > 2 && string[0] === '/' && string[1] === '/') {
+     return string[2]
+   } else {
+     return ''
+   }
+ }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 1b01a6e..149c7b2 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -2,23 +2,44 @@ const {equal} = require('assert')
 
 describe('StringCalculator', function () {
   const StringCalculator = require('../lib/string-calculator')
-  it('returns 0 on empty string', function () {
-    equal(StringCalculator.add(''), 0)
-  })
 
-  it('returns number for a single number string', function () {
-    equal(StringCalculator.add('1'), 1)
-  })
+  describe('#add', function () {
+    const {add} = StringCalculator
 
-  it('returns sum for a comma separated string with two values', function () {
-    equal(StringCalculator.add('1,2'), 3)
-  })
+    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('returns sum for an unknown number of comma separated values', function () {
-    equal(StringCalculator.add('1,2,3,4'), 10)
+    it('returns sum for an unknown number of comma separated values', function () {
+      equal(add('1,2,3,4'), 10)
+    })
+
+    it('returns sum for an unknown number of an end-of-line separated values', function () {
+      equal(add('1\n2'), 3)
+    })
+
+    it.skip('returns sum for custom delimited values', function () {
+      equal(add('//x\n1x2'), 3)
+    })
   })
 
-  it('returns sum for an unknown number of an end-of-line separated values', function () {
-    equal(StringCalculator.add('1\n2'), 3)
+  describe('#parseCustomDelimiter', function () {
+    const {parseCustomDelimiter: parse} = StringCalculator
+
+    it('returns empty string if no custom delimiter is specified', function () {
+      equal(parse('1,2'), '')
+    })
+
+    it('returns a custom delimiter', function () {
+      equal(parse('//x\n1x2'), 'x')
+    })
   })
 })

From ae87c7e20da569ce05a5b5eb08e1039da8dd97a9 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 18:11:56 +0100
Subject: [PATCH 09/11] added custom delimiter registration

---
 lib/string-calculator.js       | 18 +++++++++++-------
 test/string-calculator-test.js |  2 +-
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index b7d6391..7895b35 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -5,16 +5,20 @@ module.exports.add = function (string) {
   let customDelimiter = module.exports.parseCustomDelimiter(string)
   let sum = 0
   let numbers = string.split(/,|\n/g)
+  if (customDelimiter !== '') {
+    string = string.substr(3, string.length)
+    numbers = string.split(customDelimiter)
+  }
   for (let i = 0; i < numbers.length; i++) {
     sum += parseInt(numbers[i])
   }
   return sum
 }
 
- module.exports.parseCustomDelimiter = function (string) {
-   if(string.length > 2 && string[0] === '/' && string[1] === '/') {
-     return string[2]
-   } else {
-     return ''
-   }
- }
+module.exports.parseCustomDelimiter = function (string) {
+  if (string.length > 2 && string[0] === '/' && string[1] === '/') {
+    return string[2]
+  } else {
+    return ''
+  }
+}
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 149c7b2..7bc862d 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -26,7 +26,7 @@ describe('StringCalculator', function () {
       equal(add('1\n2'), 3)
     })
 
-    it.skip('returns sum for custom delimited values', function () {
+    it('returns sum for custom delimited values', function () {
       equal(add('//x\n1x2'), 3)
     })
   })

From 486c8c71f2ac75a2c5ccc08299d6877a0cb60e72 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 18:14:13 +0100
Subject: [PATCH 10/11] fix

---
 lib/string-calculator.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index 7895b35..ce2ac96 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -1,4 +1,6 @@
-module.exports.add = function (string) {
+module.exports = { add, parseCustomDelimiter }
+
+function add (string) {
   if (string.length === 0) {
     return 0
   }
@@ -15,7 +17,7 @@ module.exports.add = function (string) {
   return sum
 }
 
-module.exports.parseCustomDelimiter = function (string) {
+function parseCustomDelimiter (string) {
   if (string.length > 2 && string[0] === '/' && string[1] === '/') {
     return string[2]
   } else {

From d8b6d1baac8d66dbb8b06fa0b592625c522317f7 Mon Sep 17 00:00:00 2001
From: Ivo von Putzer Reibegg <ivo.putzer@gmail.com>
Date: Mon, 12 Dec 2016 18:18:47 +0100
Subject: [PATCH 11/11] refactoring on custom delimited

---
 lib/string-calculator.js       | 10 +++++-----
 test/string-calculator-test.js |  4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/lib/string-calculator.js b/lib/string-calculator.js
index ce2ac96..0a3232b 100644
--- a/lib/string-calculator.js
+++ b/lib/string-calculator.js
@@ -4,12 +4,14 @@ function add (string) {
   if (string.length === 0) {
     return 0
   }
-  let customDelimiter = module.exports.parseCustomDelimiter(string)
+  let customDelimiter = parseCustomDelimiter(string)
   let sum = 0
-  let numbers = string.split(/,|\n/g)
-  if (customDelimiter !== '') {
+  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])
@@ -20,7 +22,5 @@ function add (string) {
 function parseCustomDelimiter (string) {
   if (string.length > 2 && string[0] === '/' && string[1] === '/') {
     return string[2]
-  } else {
-    return ''
   }
 }
diff --git a/test/string-calculator-test.js b/test/string-calculator-test.js
index 7bc862d..a92e3d6 100644
--- a/test/string-calculator-test.js
+++ b/test/string-calculator-test.js
@@ -34,8 +34,8 @@ describe('StringCalculator', function () {
   describe('#parseCustomDelimiter', function () {
     const {parseCustomDelimiter: parse} = StringCalculator
 
-    it('returns empty string if no custom delimiter is specified', function () {
-      equal(parse('1,2'), '')
+    it('returns undefined if no custom delimiter is specified', function () {
+      equal(parse('1,2'), undefined)
     })
 
     it('returns a custom delimiter', function () {