diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index 8a7856b541..9dee7fae19 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -7205,16 +7205,6 @@ parameters:
 			count: 1
 			path: tests/PhpSpreadsheetTests/Reader/Xlsx/AutoFilterTest.php
 
-		-
-			message: "#^Function PhpOffice\\\\PhpSpreadsheetTests\\\\Reader\\\\getTitleText\\(\\) has no return typehint specified\\.$#"
-			count: 1
-			path: tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php
-
-		-
-			message: "#^Function PhpOffice\\\\PhpSpreadsheetTests\\\\Reader\\\\getTitleText\\(\\) has parameter \\$title with no typehint specified\\.$#"
-			count: 1
-			path: tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php
-
 		-
 			message: "#^Cannot call method setMinimumConditionalFormatValueObject\\(\\) on PhpOffice\\\\PhpSpreadsheet\\\\Style\\\\ConditionalFormatting\\\\ConditionalDataBar\\|null\\.$#"
 			count: 1
@@ -7245,11 +7235,6 @@ parameters:
 			count: 1
 			path: tests/PhpSpreadsheetTests/Reader/Xlsx/ConditionalFormattingDataBarXlsxTest.php
 
-		-
-			message: "#^Method PhpOffice\\\\PhpSpreadsheetTests\\\\Reader\\\\XlsxTest\\:\\:testStripsWhiteSpaceFromStyleString\\(\\) has parameter \\$string with no typehint specified\\.$#"
-			count: 1
-			path: tests/PhpSpreadsheetTests/Reader/XlsxTest.php
-
 		-
 			message: "#^Method PhpOffice\\\\PhpSpreadsheetTests\\\\Reader\\\\Xml\\\\XmlTest\\:\\:testInvalidSimpleXML\\(\\) has parameter \\$filename with no typehint specified\\.$#"
 			count: 1
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php
index 5e1711390d..f9fa54ab43 100644
--- a/tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/ChartsTitleTest.php
@@ -1,23 +1,24 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
+use PhpOffice\PhpSpreadsheet\Chart\Title;
 use PhpOffice\PhpSpreadsheet\IOFactory;
 use PHPUnit\Framework\TestCase;
 
-function getTitleText($title)
+class ChartsTitleTest extends TestCase
 {
-    if (null === $title || null === $title->getCaption()) {
-        return null;
-    }
+    private static function getTitleText(?Title $title): ?string
+    {
+        if (null === $title || empty($title->getCaption())) {
+            return null;
+        }
 
-    return implode("\n", array_map(function ($rt) {
-        return $rt->getPlainText();
-    }, $title->getCaption()));
-}
+        return implode("\n", array_map(function ($rt) {
+            return $rt->getPlainText();
+        }, $title->getCaption())); // @phpstan-ignore-line
+    }
 
-class ChartsTitleTest extends TestCase
-{
     public function testChartTitles(): void
     {
         $filename = 'tests/data/Reader/XLSX/excelChartsTest.xlsx';
@@ -31,34 +32,34 @@ public function testChartTitles(): void
 
         // No title or axis labels
         $chart1 = $charts[0];
-        $title = getTitleText($chart1->getTitle());
+        $title = self::getTitleText($chart1->getTitle());
         self::assertEmpty($title);
-        self::assertEmpty(getTitleText($chart1->getXAxisLabel()));
-        self::assertEmpty(getTitleText($chart1->getYAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart1->getXAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart1->getYAxisLabel()));
 
         // Title, no axis labels
         $chart2 = $charts[1];
 
-        self::assertEquals('Chart with Title and no Axis Labels', getTitleText($chart2->getTitle()));
-        self::assertEmpty(getTitleText($chart2->getXAxisLabel()));
-        self::assertEmpty(getTitleText($chart2->getYAxisLabel()));
+        self::assertEquals('Chart with Title and no Axis Labels', self::getTitleText($chart2->getTitle()));
+        self::assertEmpty(self::getTitleText($chart2->getXAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart2->getYAxisLabel()));
 
         // No title, only horizontal axis label
         $chart3 = $charts[2];
-        self::assertEmpty(getTitleText($chart3->getTitle()));
-        self::assertEquals('Horizontal Axis Title Only', getTitleText($chart3->getXAxisLabel()));
-        self::assertEmpty(getTitleText($chart3->getYAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart3->getTitle()));
+        self::assertEquals('Horizontal Axis Title Only', self::getTitleText($chart3->getXAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart3->getYAxisLabel()));
 
         // No title, only vertical axis label
         $chart4 = $charts[3];
-        self::assertEmpty(getTitleText($chart4->getTitle()));
-        self::assertEquals('Vertical Axis Title Only', getTitleText($chart4->getYAxisLabel()));
-        self::assertEmpty(getTitleText($chart4->getXAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart4->getTitle()));
+        self::assertEquals('Vertical Axis Title Only', self::getTitleText($chart4->getYAxisLabel()));
+        self::assertEmpty(self::getTitleText($chart4->getXAxisLabel()));
 
         // Title and both axis labels
         $chart5 = $charts[4];
-        self::assertEquals('Complete Annotations', getTitleText($chart5->getTitle()));
-        self::assertEquals('Horizontal Axis Title', getTitleText($chart5->getXAxisLabel()));
-        self::assertEquals('Vertical Axis Title', getTitleText($chart5->getYAxisLabel()));
+        self::assertEquals('Complete Annotations', self::getTitleText($chart5->getTitle()));
+        self::assertEquals('Horizontal Axis Title', self::getTitleText($chart5->getXAxisLabel()));
+        self::assertEquals('Vertical Axis Title', self::getTitleText($chart5->getYAxisLabel()));
     }
 }
diff --git a/tests/PhpSpreadsheetTests/Reader/CondNumFmtTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/CondNumFmtTest.php
similarity index 96%
rename from tests/PhpSpreadsheetTests/Reader/CondNumFmtTest.php
rename to tests/PhpSpreadsheetTests/Reader/Xlsx/CondNumFmtTest.php
index c7474c6ac3..350baa76b8 100644
--- a/tests/PhpSpreadsheetTests/Reader/CondNumFmtTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/CondNumFmtTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 use PhpOffice\PhpSpreadsheet\Style\Conditional;
diff --git a/tests/PhpSpreadsheetTests/Reader/OddColumnReadFilter.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/OddColumnReadFilter.php
similarity index 84%
rename from tests/PhpSpreadsheetTests/Reader/OddColumnReadFilter.php
rename to tests/PhpSpreadsheetTests/Reader/Xlsx/OddColumnReadFilter.php
index b937331488..028f2fa32e 100644
--- a/tests/PhpSpreadsheetTests/Reader/OddColumnReadFilter.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/OddColumnReadFilter.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Reader\IReadFilter;
 
diff --git a/tests/PhpSpreadsheetTests/Reader/SheetsXlsxChartTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/SheetsXlsxChartTest.php
similarity index 97%
rename from tests/PhpSpreadsheetTests/Reader/SheetsXlsxChartTest.php
rename to tests/PhpSpreadsheetTests/Reader/Xlsx/SheetsXlsxChartTest.php
index 9c478c4a7e..d701c3c744 100644
--- a/tests/PhpSpreadsheetTests/Reader/SheetsXlsxChartTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/SheetsXlsxChartTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Chart\DataSeries;
 use PhpOffice\PhpSpreadsheet\IOFactory;
diff --git a/tests/PhpSpreadsheetTests/Reader/Xlsx2Test.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/Xlsx2Test.php
similarity index 99%
rename from tests/PhpSpreadsheetTests/Reader/Xlsx2Test.php
rename to tests/PhpSpreadsheetTests/Reader/Xlsx/Xlsx2Test.php
index cef721211f..8212f089a9 100644
--- a/tests/PhpSpreadsheetTests/Reader/Xlsx2Test.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/Xlsx2Test.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\IOFactory;
 use PhpOffice\PhpSpreadsheet\Shared\File;
diff --git a/tests/PhpSpreadsheetTests/Reader/XlsxTest.php b/tests/PhpSpreadsheetTests/Reader/Xlsx/XlsxTest.php
similarity index 98%
rename from tests/PhpSpreadsheetTests/Reader/XlsxTest.php
rename to tests/PhpSpreadsheetTests/Reader/Xlsx/XlsxTest.php
index 611f5656f5..4a3a421f76 100644
--- a/tests/PhpSpreadsheetTests/Reader/XlsxTest.php
+++ b/tests/PhpSpreadsheetTests/Reader/Xlsx/XlsxTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace PhpOffice\PhpSpreadsheetTests\Reader;
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataValidation;
@@ -237,7 +237,7 @@ public function testLoadSaveWithEmptyDrawings(): void
      *
      * @dataProvider providerStripsWhiteSpaceFromStyleString
      */
-    public function testStripsWhiteSpaceFromStyleString($string): void
+    public function testStripsWhiteSpaceFromStyleString(string $string): void
     {
         $string = Xlsx::stripWhiteSpaceFromStyleString($string);
         self::assertEquals(preg_match('/\s/', $string), 0);