diff --git a/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php b/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
index 1e1b5ecc..f0ce32fb 100644
--- a/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
+++ b/tests/PhpSpreadsheetTests/Cell/DataTypeTest.php
@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheetTests\Cell;
 
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
+use PhpOffice\PhpSpreadsheet\RichText\RichText;
 use PHPUnit\Framework\TestCase;
 
 class DataTypeTest extends TestCase
@@ -14,4 +15,47 @@ class DataTypeTest extends TestCase
         self::assertGreaterThan(0, count($result));
         self::assertArrayHasKey('#NULL!', $result);
     }
+
+    public function testCheckString()
+    {
+        $richText = new RichText();
+        $result1 = DataType::checkString($richText);
+        self::assertSame($richText, $result1);
+
+        $stringLimit = 32767;
+        $randString = $this->randr($stringLimit + 10);
+        $result2 = DataType::checkString($randString);
+        self::assertSame($stringLimit, strlen($result2));
+
+        $dirtyString = "bla bla\r\n bla\r test\n";
+        $expected = "bla bla\n bla\n test\n";
+        $result3 = DataType::checkString($dirtyString);
+        self::assertSame($expected, $result3);
+    }
+
+    /**
+     * @param int $length
+     *
+     * @return string
+     */
+    private function randr($length = 8)
+    {
+        $string = '';
+        for ($i = 0; $i < $length; ++$i) {
+            $x = mt_rand(0, 2);
+            switch ($x) {
+                case 0: $string .= chr(mt_rand(97, 122));
+
+                break;
+                case 1: $string .= chr(mt_rand(65, 90));
+
+                break;
+                case 2: $string .= chr(mt_rand(48, 57));
+
+                break;
+            }
+        }
+
+        return $string;
+    }
 }