Written DataValidation was corrupted

Fixes #290

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Can read very small HTML files - [#194](https://github.com/PHPOffice/PhpSpreadsheet/issues/194)
+- Written DataValidation was corrupted - [#290](https://github.com/PHPOffice/PhpSpreadsheet/issues/290)
 
 ### BREAKING CHANGE
 

src/PhpSpreadsheet/Cell/DataValidation.php

@@ -449,8 +449,8 @@ class DataValidation
         return md5(
             $this->formula1 .
             $this->formula2 .
-            $this->type = self::TYPE_NONE .
-            $this->errorStyle = self::STYLE_STOP .
+            $this->type .
+            $this->errorStyle .
             $this->operator .
             ($this->allowBlank ? 't' : 'f') .
             ($this->showDropDown ? 't' : 'f') .

tests/PhpSpreadsheetTests/Cell/DataValidationTest.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Cell;
+
+use PhpOffice\PhpSpreadsheet\Cell\DataValidation;
+use PHPUnit\Framework\TestCase;
+
+class DataValidationTest extends TestCase
+{
+    public function testNoValidation()
+    {
+        $dataValidation = new DataValidation();
+        self::assertSame('090624f04837265d79323c4a1b7e89d1', $dataValidation->getHashCode());
+        $dataValidation->setType(DataValidation::TYPE_CUSTOM);
+
+        self::assertSame('778f6c9e0ffcd5eaa7d8e1432d67f919', $dataValidation->getHashCode());
+        self::assertSame('778f6c9e0ffcd5eaa7d8e1432d67f919', $dataValidation->getHashCode(), 'getHashCode() should not have side effect');
+    }
+}