Add unit test

Author: jaywilliams

tests/PHPExif/Mapper/NativeMapperTest.php

@@ -138,6 +138,21 @@ public function testMapRawDataCorrectlyFormatsFocalLength()
         $this->assertEquals(6, reset($mapped));
     }
 
+    /**
+     * @group mapper
+     * @covers \PHPExif\Mapper\Native::mapRawData
+     */
+    public function testMapRawDataCorrectlyFormatsFocalLengthDivisionByZero()
+    {
+        $rawData = array(
+            \PHPExif\Mapper\Native::FOCALLENGTH => '1/0',
+        );
+
+        $mapped = $this->mapper->mapRawData($rawData);
+
+        $this->assertEquals(0, reset($mapped));
+    }
+
     /**
      * @group mapper
      * @covers \PHPExif\Mapper\Native::mapRawData