fix: correct savePath check in MemcachedHandler constructor

system/Session/Handlers/MemcachedHandler.php

@@ -63,7 +63,7 @@ public function __construct(SessionConfig $config, string $ipAddress)
 
         $this->sessionExpiration = $config->expiration;
 
-        if ($this->savePath !== '') {
+        if ($this->savePath === '') {
             throw SessionException::forEmptySavepath();
         }
 

tests/system/Session/Handlers/MemcachedHandlerTest.php

@@ -0,0 +1,131 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Session\Handlers;
+
+use CodeIgniter\Session\Exceptions\SessionException;
+use CodeIgniter\Test\CIUnitTestCase;
+use CodeIgniter\Test\TestLogger;
+use Config\Logger as LoggerConfig;
+use Config\Session as SessionConfig;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\RequiresPhpExtension;
+
+/**
+ * @internal
+ */
+#[Group('DatabaseLive')]
+#[RequiresPhpExtension('memcached')]
+final class MemcachedHandlerTest extends CIUnitTestCase
+{
+    private string $sessionDriver   = MemcachedHandler::class;
+    private string $sessionName     = 'ci_session';
+    private string $sessionSavePath = '127.0.0.1:11211';
+    private string $userIpAddress   = '127.0.0.1';
+
+    /**
+     * @param array<string, bool|int|string|null> $options Replace values for `Config\Session`.
+     */
+    protected function getInstance($options = []): MemcachedHandler
+    {
+        $defaults = [
+            'driver'            => $this->sessionDriver,
+            'cookieName'        => $this->sessionName,
+            'expiration'        => 7200,
+            'savePath'          => $this->sessionSavePath,
+            'matchIP'           => false,
+            'timeToUpdate'      => 300,
+            'regenerateDestroy' => false,
+        ];
+        $sessionConfig = new SessionConfig();
+        $config        = array_merge($defaults, $options);
+
+        foreach ($config as $key => $value) {
+            $sessionConfig->{$key} = $value;
+        }
+
+        $handler = new MemcachedHandler($sessionConfig, $this->userIpAddress);
+        $handler->setLogger(new TestLogger(new LoggerConfig()));
+
+        return $handler;
+    }
+
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        MemcachedHandler::resetPersistentConnections();
+    }
+
+    public function testConstructorThrowsWithEmptySavePath(): void
+    {
+        $this->expectException(SessionException::class);
+
+        $this->getInstance(['savePath' => '']);
+    }
+
+    public function testConstructorDoesNotThrowWithValidSavePath(): void
+    {
+        $handler = $this->getInstance(['savePath' => '127.0.0.1:11211']);
+
+        $this->assertInstanceOf(MemcachedHandler::class, $handler);
+    }
+
+    public function testOpen(): void
+    {
+        $handler = $this->getInstance();
+        $this->assertTrue($handler->open($this->sessionSavePath, $this->sessionName));
+    }
+
+    public function testWriteAndReadBack(): void
+    {
+        $handler = $this->getInstance();
+        $handler->open($this->sessionSavePath, $this->sessionName);
+
+        $sessionId = '555556b43phsnnf8if6bo33b635e4447';
+
+        // Initial read to acquire lock and set session ID
+        $this->assertSame('', $handler->read($sessionId));
+
+        $data = <<<'DATA'
+            __ci_last_regenerate|i:1664607454;_ci_previous_url|s:32:"http://localhost:8080/index.php/";key|s:5:"value";
+            DATA;
+        $this->assertTrue($handler->write($sessionId, $data));
+
+        $handler->close();
+
+        // Read back in a new handler to verify persistence
+        $handler2 = $this->getInstance();
+        $handler2->open($this->sessionSavePath, $this->sessionName);
+
+        $this->assertSame($data, $handler2->read($sessionId));
+
+        $handler2->close();
+    }
+
+    public function testReadEmptySession(): void
+    {
+        $handler = $this->getInstance();
+        $handler->open($this->sessionSavePath, $this->sessionName);
+
+        $this->assertSame('', $handler->read('123456b43phsnnf8if6bo33b635e4321'));
+
+        $handler->close();
+    }
+
+    public function testGC(): void
+    {
+        $handler = $this->getInstance();
+        $this->assertSame(1, $handler->gc(3600));
+    }
+}

user_guide_src/source/changelogs/v4.7.1.rst

@@ -33,6 +33,7 @@ Bugs Fixed
 **********
 
 - **ContentSecurityPolicy:** Fixed a bug where ``generateNonces()`` produces corrupted JSON responses by replacing CSP nonce placeholders with unescaped double quotes. The method now automatically JSON-escapes nonce attributes when the response Content-Type is JSON.
+- **Session:** Fixed a bug in ``MemcachedHandler`` where the constructor incorrectly threw an exception when ``savePath`` was not empty.
 
 See the repo's
 `CHANGELOG.md <https://github.com/codeigniter4/CodeIgniter4/blob/develop/CHANGELOG.md>`_