Fix Typo in Style exportArray quotePrefix

Fix PHPOffice#4422. Add tests.

Author: oleibman

src/PhpSpreadsheet/Style/Style.php

@@ -698,7 +698,7 @@ protected function exportArray1(): array
         $this->exportArray2($exportedArray, 'font', $this->getFont());
         $this->exportArray2($exportedArray, 'numberFormat', $this->getNumberFormat());
         $this->exportArray2($exportedArray, 'protection', $this->getProtection());
-        $this->exportArray2($exportedArray, 'quotePrefx', $this->getQuotePrefix());
+        $this->exportArray2($exportedArray, 'quotePrefix', $this->getQuotePrefix());
 
         return $exportedArray;
     }

tests/PhpSpreadsheetTests/Style/ExportArrayTest.php

@@ -4,6 +4,7 @@
 
 namespace PhpOffice\PhpSpreadsheetTests\Style;
 
+use PhpOffice\PhpSpreadsheet\Cell\DataType;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Style\Alignment;
 use PhpOffice\PhpSpreadsheet\Style\Border;
@@ -287,4 +288,24 @@ public function testFillColors(): void
         );
         $spreadsheet->disconnectWorksheets();
     }
+
+    public function testQuotePrefix(): void
+    {
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->getCell('A1')
+            ->setValueExplicit('=1+2', DataType::TYPE_STRING);
+        self::assertSame('=1+2', $sheet->getCell('A1')->getCalculatedValue());
+        self::assertTrue($sheet->getStyle('A1')->getQuotePrefix());
+        $sheet->getCell('A2')->setValue('=1+2');
+        self::assertSame(3, $sheet->getCell('A2')->getCalculatedValue());
+        self::assertFalse($sheet->getStyle('A2')->getQuotePrefix());
+        $styleArray1 = $sheet->getStyle('A1')->exportArray();
+        $styleArray2 = $sheet->getStyle('A2')->exportArray();
+        $sheet->getStyle('B1')->applyFromArray($styleArray1);
+        $sheet->getStyle('B2')->applyFromArray($styleArray2);
+        self::assertTrue($sheet->getStyle('B1')->getQuotePrefix());
+        self::assertFalse($sheet->getStyle('B2')->getQuotePrefix());
+        $spreadsheet->disconnectWorksheets();
+    }
 }