diff --git a/composer.json b/composer.json
index e703580fd4b9..b291ea49c21c 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
         "mikey179/vfsstream": "^1.6.12",
         "nexusphp/tachycardia": "^2.0",
         "phpstan/extension-installer": "^1.4",
-        "phpstan/phpstan": "^2.2.1",
+        "phpstan/phpstan": "^2.2.15",
         "phpstan/phpstan-strict-rules": "^2.0",
         "phpunit/phpcov": "^9.0.2 || ^10.0",
         "phpunit/phpunit": "^10.5.16 || ^11.2",
diff --git a/tests/system/Config/ServicesTest.php b/tests/system/Config/ServicesTest.php
index 66c9158e67ab..f9b8d8158c39 100644
--- a/tests/system/Config/ServicesTest.php
+++ b/tests/system/Config/ServicesTest.php
@@ -197,7 +197,8 @@ public function testNewUnsharedLanguage(): void
     {
         $actual = Services::language(null, false);
         $this->assertInstanceOf(Language::class, $actual);
-        $this->assertSame('en', $actual->getLocale());
+        $locale = $actual->getLocale();
+        $this->assertSame('en', $locale);
 
         Services::language('la', false);
         $this->assertSame('en', $actual->getLocale());
diff --git a/tests/system/Email/EmailTest.php b/tests/system/Email/EmailTest.php
index fc94686589d1..a54bf8d90ce5 100644
--- a/tests/system/Email/EmailTest.php
+++ b/tests/system/Email/EmailTest.php
@@ -713,7 +713,8 @@ public function testSetPriorityFallback(): void
 
         // Priority 6 is invalid, falls back to 3
         $email->setPriority(6);
-        $this->assertSame(3, $this->getPrivateProperty($email, 'priority'));
+        $priority = $this->getPrivateProperty($email, 'priority');
+        $this->assertSame(3, $priority);
 
         // Priority 0 is invalid, falls back to 3
         $email->setPriority(0);
diff --git a/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php b/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
index bac22a881f0a..01254f31b810 100644
--- a/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
+++ b/tests/system/Encryption/Handlers/OpenSSLHandlerTest.php
@@ -149,7 +149,8 @@ public function testInternalKeyNotModifiedByParams(): void
         $encrypter = $this->encryption->initialize($params);
         $this->assertInstanceOf(OpenSSLHandler::class, $encrypter);
 
-        $this->assertSame('original-key-value', $encrypter->key);
+        $key = $encrypter->key;
+        $this->assertSame('original-key-value', $key);
 
         $message      = 'This is a plain-text message.';
         $differentKey = 'temporary-param-key';
diff --git a/tests/system/Encryption/Handlers/SodiumHandlerTest.php b/tests/system/Encryption/Handlers/SodiumHandlerTest.php
index 47406cef00d0..fe63cec36fb9 100644
--- a/tests/system/Encryption/Handlers/SodiumHandlerTest.php
+++ b/tests/system/Encryption/Handlers/SodiumHandlerTest.php
@@ -139,7 +139,8 @@ public function testInternalKeyNotModifiedByParams(): void
         $encrypter         = $this->encryption->initialize($this->config);
         $this->assertInstanceOf(SodiumHandler::class, $encrypter);
 
-        $this->assertSame($originalKey, $encrypter->key);
+        $key = $encrypter->key;
+        $this->assertSame($originalKey, $key);
 
         $message      = 'This is a plain-text message.';
         $differentKey = sodium_crypto_secretbox_keygen();
diff --git a/tests/system/Entity/EntityTest.php b/tests/system/Entity/EntityTest.php
index be8f64f31775..3aff3fac3a10 100644
--- a/tests/system/Entity/EntityTest.php
+++ b/tests/system/Entity/EntityTest.php
@@ -373,8 +373,9 @@ public function testCastInteger(): void
 
         $entity->first = 3.1;
 
-        $this->assertIsInt($entity->first);
-        $this->assertSame(3, $entity->first);
+        $first = $entity->first;
+        $this->assertIsInt($first);
+        $this->assertSame(3, $first);
 
         $entity->first = 3.6;
 
diff --git a/tests/system/Events/EventsTest.php b/tests/system/Events/EventsTest.php
index bfdef1e2bbe9..39be06b1235b 100644
--- a/tests/system/Events/EventsTest.php
+++ b/tests/system/Events/EventsTest.php
@@ -69,7 +69,8 @@ public function testInitialize(): void
 
         // but we should be able to change it through the backdoor
         MockEvents::setFiles(['/peanuts']);
-        $this->assertSame(['/peanuts'], Events::getFiles());
+        $files = Events::getFiles();
+        $this->assertSame(['/peanuts'], $files);
 
         // re-initializing should have no effect
         MockEvents::initialize();
diff --git a/tests/system/HTTP/IncomingRequestTest.php b/tests/system/HTTP/IncomingRequestTest.php
index 90e6c7d57e90..464b46e2ce2c 100644
--- a/tests/system/HTTP/IncomingRequestTest.php
+++ b/tests/system/HTTP/IncomingRequestTest.php
@@ -1057,7 +1057,8 @@ public function testGetIPAddressNormal(): void
         $request = new Request(new App());
         $request->populateHeaders();
 
-        $this->assertSame($expected, $request->getIPAddress());
+        $ipAddress = $request->getIPAddress();
+        $this->assertSame($expected, $ipAddress);
         // call a second time to exercise the initial conditional block in getIPAddress()
         $this->assertSame($expected, $request->getIPAddress());
     }
diff --git a/tests/system/HTTP/RequestTest.php b/tests/system/HTTP/RequestTest.php
index e1f70bdd272f..2dafdc4fd792 100644
--- a/tests/system/HTTP/RequestTest.php
+++ b/tests/system/HTTP/RequestTest.php
@@ -562,7 +562,8 @@ public function testGetIPAddressNormal(): void
         $expected = '123.123.123.123';
         service('superglobals')->setServer('REMOTE_ADDR', $expected);
         $this->request = new Request(new App());
-        $this->assertSame($expected, $this->request->getIPAddress());
+        $ipAddress     = $this->request->getIPAddress();
+        $this->assertSame($expected, $ipAddress);
         // call a second time to exercise the initial conditional block in getIPAddress()
         $this->assertSame($expected, $this->request->getIPAddress());
     }
diff --git a/tests/system/Helpers/FormHelperTest.php b/tests/system/Helpers/FormHelperTest.php
index 73cbe2430a5f..c24d34b04a3e 100644
--- a/tests/system/Helpers/FormHelperTest.php
+++ b/tests/system/Helpers/FormHelperTest.php
@@ -870,7 +870,8 @@ public function testSetValue(): void
     public function testSetSelect(): void
     {
         $_SESSION['_ci_old_input']['post']['foo'] = 'bar';
-        $this->assertSame(' selected="selected"', set_select('foo', 'bar'));
+        $selected                                 = set_select('foo', 'bar');
+        $this->assertSame(' selected="selected"', $selected);
 
         $_SESSION['_ci_old_input']['post']['foo'] = ['foo' => 'bar'];
         $this->assertSame(' selected="selected"', set_select('foo', 'bar'));
@@ -890,7 +891,8 @@ public function testSetCheckbox(): void
             ],
         ];
 
-        $this->assertSame(' checked="checked"', set_checkbox('foo', 'bar'));
+        $checked = set_checkbox('foo', 'bar');
+        $this->assertSame(' checked="checked"', $checked);
 
         $_SESSION = [
             '_ci_old_input' => [
@@ -919,7 +921,8 @@ public function testSetCheckboxWithValueZero(): void
             ],
         ];
 
-        $this->assertSame(' checked="checked"', set_checkbox('foo', '0'));
+        $checked = set_checkbox('foo', '0');
+        $this->assertSame(' checked="checked"', $checked);
 
         $_SESSION = [
             '_ci_old_input' => [
diff --git a/tests/system/Helpers/TextHelperTest.php b/tests/system/Helpers/TextHelperTest.php
index 212f2797bacf..a4702db4b604 100644
--- a/tests/system/Helpers/TextHelperTest.php
+++ b/tests/system/Helpers/TextHelperTest.php
@@ -161,7 +161,8 @@ public function testIncrementString(): void
         $this->assertSame('my-test_1', increment_string('my-test'));
         $this->assertSame('my-test-1', increment_string('my-test', '-'));
         $this->assertSame('file_5', increment_string('file_4'));
-        $this->assertSame('file-5', increment_string('file-4', '-'));
+        $incremented = increment_string('file-4', '-');
+        $this->assertSame('file-5', $incremented);
         $this->assertSame('file-5', increment_string('file-4', '-'));
         $this->assertSame('file-1', increment_string('file', '-', 1));
         $this->assertSame('124', increment_string('123', ''));
diff --git a/tests/system/Language/LanguageTest.php b/tests/system/Language/LanguageTest.php
index 6233941e7d75..b67292da2236 100644
--- a/tests/system/Language/LanguageTest.php
+++ b/tests/system/Language/LanguageTest.php
@@ -338,10 +338,12 @@ public function testLangKeepLocale(): void
         $lang = service('language', 'en', true);
 
         lang('Language.languageGetLineInvalidArgumentException');
-        $this->assertSame('en', $lang->getLocale());
+        $locale = $lang->getLocale();
+        $this->assertSame('en', $locale);
 
         lang('Language.languageGetLineInvalidArgumentException', [], 'ru');
-        $this->assertSame('en', $lang->getLocale());
+        $locale = $lang->getLocale();
+        $this->assertSame('en', $locale);
 
         lang('Language.languageGetLineInvalidArgumentException');
         $this->assertSame('en', $lang->getLocale());
diff --git a/tests/system/Session/Handlers/Database/RedisHandlerTest.php b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
index 637132669aec..c2f549e31659 100644
--- a/tests/system/Session/Handlers/Database/RedisHandlerTest.php
+++ b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
@@ -142,7 +142,8 @@ public function testSecondaryReadAfterClose(): void
         $expected = <<<'DATA'
             __ci_last_regenerate|i:1664607454;_ci_previous_url|s:32:"http://localhost:8080/index.php/";key|s:5:"value";
             DATA;
-        $this->assertSame($expected, $handler->read('555556b43phsnnf8if6bo33b635e4447'));
+        $data = $handler->read('555556b43phsnnf8if6bo33b635e4447');
+        $this->assertSame($expected, $data);
 
         $handler->close();
 
diff --git a/tests/system/Throttle/ThrottleTest.php b/tests/system/Throttle/ThrottleTest.php
index 98751a86781b..b16606341ab7 100644
--- a/tests/system/Throttle/ThrottleTest.php
+++ b/tests/system/Throttle/ThrottleTest.php
@@ -39,7 +39,8 @@ public function testTokenTime(): void
         $throttler = new Throttler($this->cache);
 
         // tokenTime should be 0 to start
-        $this->assertSame(0, $throttler->getTokenTime());
+        $tokenTime = $throttler->getTokenTime();
+        $this->assertSame(0, $tokenTime);
 
         // set $rate
         $rate = 1;    // allow 1 request per minute
diff --git a/tests/system/View/ParserTest.php b/tests/system/View/ParserTest.php
index 95d807729c58..36e8707430d6 100644
--- a/tests/system/View/ParserTest.php
+++ b/tests/system/View/ParserTest.php
@@ -962,7 +962,8 @@ public function testCachedRender(): void
         $this->parser->setVar('teststring', 'Hello World');
 
         $expected = "<h1>Hello World</h1>\n";
-        $this->assertSame($expected, $this->parser->render('template1', ['cache' => 10, 'cache_name' => 'HelloWorld']));
+        $output   = $this->parser->render('template1', ['cache' => 10, 'cache_name' => 'HelloWorld']);
+        $this->assertSame($expected, $output);
         // this second renderings should go thru the cache
         $this->assertSame($expected, $this->parser->render('template1', ['cache' => 10, 'cache_name' => 'HelloWorld']));
     }