Get Us Closer to Csv Not Autodetect By Default

This has been requested a few times, most recently issue PHPOffice#4092. Because it's a breaking change, I haven't proceeded with it. But, because I have a breaking change PR PHPOffice#4240 already in the queue, this gives a plan for getting where we want to go (under the extremely likely assumption that most users don't deal with Csv files with Mac line endings). This PR doesn't change the current behavior, but it gets us to a state where a single-line change will be sufficient when the time comes for a new major release.

src/PhpSpreadsheet/Reader/Csv.php

@@ -84,10 +84,13 @@ class Csv extends BaseReader
      */
     private static $constructorCallback;
 
+    /** Will be changed to false in next major release */
+    public const DEFAULT_TEST_AUTODETECT = true;
+
     /**
      * Attempt autodetect line endings (deprecated after PHP8.1)?
      */
-    private bool $testAutodetect = true;
+    private bool $testAutodetect = self::DEFAULT_TEST_AUTODETECT;
 
     protected bool $castFormattedNumberToNumeric = false;
 

tests/PhpSpreadsheetTests/Reader/Csv/CsvLineEndingTest.php

@@ -12,6 +12,8 @@ class CsvLineEndingTest extends TestCase
 {
     private string $tempFile = '';
 
+    private static bool $alwaysFalse = false;
+
     protected function tearDown(): void
     {
         if ($this->tempFile !== '') {
@@ -32,6 +34,9 @@ public function testEndings(string $ending): void
         $data = ['123', '456', '789'];
         file_put_contents($filename, implode($ending, $data));
         $reader = new Csv();
+        if (Csv::DEFAULT_TEST_AUTODETECT === self::$alwaysFalse) {
+            $reader->setTestAutoDetect(true);
+        }
         $spreadsheet = $reader->load($filename);
         $sheet = $spreadsheet->getActiveSheet();
         self::assertEquals($data[0], $sheet->getCell('A1')->getValue());