Add XMailer tests

changelog.md

@@ -3,6 +3,7 @@
 ## WIP
 * If we can't use escaping functions, refuse to do unsafe things
 * Avoid PHP 8.1 trim issue
+* Add tests for XMailer
 
 ## Version 6.5.3 (November 25th, 2021)
 * Wrong commit tagged for the 6.5.2 release!

test/PHPMailer/XMailerTest.php

@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * PHPMailer - PHP email transport unit tests.
+ * PHP version 5.5.
+ *
+ * @author    Marcus Bointon <phpmailer@synchromedia.co.uk>
+ * @author    Andy Prevost
+ * @copyright 2012 - 2020 Marcus Bointon
+ * @copyright 2004 - 2009 Andy Prevost
+ * @license   http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
+ */
+
+namespace PHPMailer\Test\PHPMailer;
+
+use PHPMailer\PHPMailer\PHPMailer;
+use PHPMailer\Test\TestCase;
+
+/**
+ * Test XMailer header setting functionality.
+ *
+ * @covers \PHPMailer\PHPMailer\PHPMailer::XMailer
+ */
+final class XMailerTest extends TestCase
+{
+    /**
+     * Test wrapping text.
+     *
+     * @dataProvider dataXMailer
+     *
+     * @param string $xmailer  Input text string.
+     * @param string $expected Expected function output.
+     */
+    public function testXMailer($xmailer, $expected)
+    {
+        $this->Mail->XMailer = $xmailer;
+        $headers = $this->Mail->createHeader();
+        if ($expected !== null) {
+            self::assertStringContainsString($expected, $headers);
+        } else {
+            self::assertStringNotContainsString('X-Mailer', $headers);
+        }
+    }
+
+    /**
+     * Data provider.
+     *
+     * @return array
+     */
+    public function dataXMailer()
+    {
+        return [
+            'empty string' => [
+                'xmailer' => '',
+                'expected' => 'X-Mailer: PHPMailer ' . PHPMailer::VERSION . ' (https://github.com/PHPMailer/PHPMailer)',
+            ],
+            'null' => [
+                'xmailer' => null,
+                'expected' => null,
+            ],
+            'whitespace' => [
+                'xmailer' => ' ',
+                'expected' => null,
+            ],
+            'non-empty string' => [
+                'xmailer' => 'test',
+                'expected' => 'X-Mailer: test',
+            ],
+            'invalid value' => [
+                'xmailer' => [],
+                'expected' => null,
+            ],
+        ];
+    }
+}