From 0e6dbb8899223f3edd251b37b416730934cc96b7 Mon Sep 17 00:00:00 2001
From: Joni Halme <joni.halme@sirumobile.com>
Date: Wed, 28 Nov 2018 09:25:38 +0200
Subject: [PATCH] fixed checksum calculation when remainder is 0, updated tests
 to match

---
 src/Modulus11.php       |  9 ++++----
 tests/Modulus11Test.php | 50 +++++++++++++++++++++++++----------------
 2 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/src/Modulus11.php b/src/Modulus11.php
index fc899ac..8831ed0 100644
--- a/src/Modulus11.php
+++ b/src/Modulus11.php
@@ -21,11 +21,12 @@ private static function getChecksum($number, $factors = null)
             $sum    += ($sequence[$i] * $factor);
         }
 
-        $calculus = 11 - $sum % 11;
+        $remainder = $sum % 11;
 
-        switch($calculus){
-            case 10: return 'X';
-            default: return $calculus;
+        switch($remainder){
+            case 0: return 0;
+            case 1: return 'X';
+            default: return 11 - $remainder;
         }
     }
 
diff --git a/tests/Modulus11Test.php b/tests/Modulus11Test.php
index defa52d..18a1154 100644
--- a/tests/Modulus11Test.php
+++ b/tests/Modulus11Test.php
@@ -6,34 +6,46 @@
 
 class Mod11Test extends \PHPUnit_Framework_TestCase
 {
-    protected $withCheckDigit1    = '1234.56.78903';
-    protected $withoutCheckDigit1 = '1234.56.7890';
-    protected $theCheckDigit1     = 3;
 
-    protected $withCheckDigit2    = '036522X';
-    protected $withoutCheckDigit2 = '036522';
-    protected $theCheckDigit2     = 'X';
-
-    public function testValidate()
+    public function provideValues()
     {
-        $this->assertTrue(Modulus11::validate($this->withCheckDigit1));
-        $this->assertTrue(Modulus11::validate($this->withCheckDigit2));
+        return array(
+            array('1234.56.78903', '1234.56.7890', 3),
+            array('036522X', '036522', 'X'),
+            array('01010104900', '0101010490', 0)
+        );
     }
 
-    public function testCalculate()
+    /**
+     * @param string $withCheckDigit
+     * @dataProvider provideValues
+     */
+    public function testValidate($withCheckDigit)
     {
-        $this->assertSame($this->theCheckDigit1, Modulus11::calculate($this->withoutCheckDigit1));
-        $this->assertSame($this->theCheckDigit2, Modulus11::calculate($this->withoutCheckDigit2));
+        $this->assertTrue(Modulus11::validate($withCheckDigit));
     }
 
-    public function testAppendCheckDigit()
+    /**
+     * @param string $withCheckDigit
+     * @param string $withoutCheckDigit
+     * @param string|int $checkDigit
+     * @dataProvider provideValues
+     */
+    public function testCalculate($withCheckDigit, $withoutCheckDigit, $checkDigit)
     {
-        $appended = Modulus11::appendCheckDigit($this->withoutCheckDigit1);
-        $this->assertSame($this->withoutCheckDigit1.$this->theCheckDigit1, $appended);
-        $this->assertTrue(Modulus11::validate($appended));
+        $this->assertSame($checkDigit, Modulus11::calculate($withoutCheckDigit));
+    }
 
-        $appended = Modulus11::appendCheckDigit($this->withoutCheckDigit2);
-        $this->assertSame($this->withoutCheckDigit2.$this->theCheckDigit2, $appended);
+    /**
+     * @param string $withCheckDigit
+     * @param string $withoutCheckDigit
+     * @param string|int $checkDigit
+     * @dataProvider provideValues
+     */
+    public function testAppendCheckDigit($withCheckDigit, $withoutCheckDigit, $checkDigit)
+    {
+        $appended = Modulus11::appendCheckDigit($withoutCheckDigit);
+        $this->assertSame($withoutCheckDigit . $checkDigit, $appended);
         $this->assertTrue(Modulus11::validate($appended));
     }