diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fda8b6d..bd6c80b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,6 +27,9 @@ jobs:
           - php: "8.0"
           - php: "8.1"
           - php: "8.2"
+          - php: "8.3"
+          - php: "8.4"
+          - php: "8.5"
 
     steps:
       - name: Checkout
diff --git a/composer b/composer
index 9508812..0a926db 100755
--- a/composer
+++ b/composer
@@ -118,9 +118,19 @@ if (!class_exists('ComposerWrapper')) {
             $modified = clone $now;
 
             //hack: DateTime $modifier argument validation. Taken from https://stackoverflow.com/a/34899724/2165434
-            $success = @$modified->modify($updateFreq);
+            try {
+                $success = @$modified->modify($updateFreq);
+            } catch (\Exception $e) {
+                $success = false;
+            }
             if ($success === false) {
-                throw new \Exception(sprintf('Wrong update frequency is requested: %s; should be valid DateTime modifier (follow %s for the help)', $updateFreq,'https://www.php.net/manual/en/datetime.modify.php'));
+                throw new \Exception(
+                    sprintf(
+                        'Wrong update frequency is requested: %s; should be valid DateTime modifier (follow %s for the help)',
+                        $updateFreq,
+                        'https://www.php.net/manual/en/datetime.modify.php'
+                    )
+                );
             }
             //endhack
 
@@ -178,13 +188,20 @@ if (!class_exists('ComposerWrapper')) {
          */
         protected $params;
 
-        public function __construct(ComposerWrapperParams $params = null)
+        public function __construct($params = null)
         {
-            if (null === $params ) {
+            if (null === $params) {
                 $this->params = new ComposerWrapperParams();
                 $this->params->loadReal();
-            } else {
+            } elseif ($params instanceof ComposerWrapperParams) {
                 $this->params = $params;
+            } else {
+                throw new \InvalidArgumentException(
+                    sprintf(
+                        "%s class can only be instantiated with ComposerWrapperParams object",
+                        __CLASS__
+                    )
+                );
             }
         }
 
diff --git a/tests/BaseTestCase.php b/tests/BaseTestCase.php
index 661b6b0..5f21729 100644
--- a/tests/BaseTestCase.php
+++ b/tests/BaseTestCase.php
@@ -20,7 +20,9 @@ private function getExpectedShebang()
     public static function callNonPublic($object, $method, $args)
     {
         $method = new ReflectionMethod($object, $method);
-        $method->setAccessible(true);
+        if (PHP_VERSION_ID < 80500) {
+            $method->setAccessible(true);
+        }
 
         return $method->invokeArgs($object, $args);
     }
@@ -28,7 +30,9 @@ public static function callNonPublic($object, $method, $args)
     protected static function setNonPublic($object, $property, $arg)
     {
         $property = new ReflectionProperty($object, $property);
-        $property->setAccessible(true);
+        if (PHP_VERSION_ID < 80500) {
+            $property->setAccessible(true);
+        }
 
         $property->setValue($object, $arg);
     }
diff --git a/tests/ComposerWrapperParamsTest.php b/tests/ComposerWrapperParamsTest.php
index 49f42bf..bcb8509 100644
--- a/tests/ComposerWrapperParamsTest.php
+++ b/tests/ComposerWrapperParamsTest.php
@@ -132,10 +132,9 @@ public function setComposerDirHandlesGoodValues()
         self::assertSame(__DIR__, $actual);
     }
 
-    public function composerDirBadDataProvider()
+    public static function composerDirBadDataProvider()
     {
         return array(
-            "access denied" => array('/var'),
             "doesn't exists" => array(__DIR__ . '/i_dont_exist'),
             "non dir" => array(__FILE__),
         );
@@ -152,6 +151,20 @@ public function setComposerDirThrowsOnBadValues($input)
         self::callNonPublic($params, 'setComposerDir', array($input));
     }
 
+    /**
+     * @test
+     */
+    public function setComposerDirThrowsOnNotWritableDirectory()
+    {
+        $root = vfsStream::setup();
+        $dir = vfsStream::newDirectory('readonly', 0555);
+        $root->addChild($dir);
+
+        $this->expectExceptionMessageRegExpCompat('\Exception', '/Wrong composer dir is requested:.*/');
+        $params = new ComposerWrapperParams();
+        self::callNonPublic($params, 'setComposerDir', array($dir->url()));
+    }
+
     /**
      * @return ComposerWrapperParams
      */
diff --git a/tests/ComposerWrapperTest.php b/tests/ComposerWrapperTest.php
index 13637e7..9556e79 100644
--- a/tests/ComposerWrapperTest.php
+++ b/tests/ComposerWrapperTest.php
@@ -17,6 +17,48 @@ private static function getInstance()
         return new $class;
     }
 
+    /**
+     * @test
+     */
+    public function acceptsParameters()
+    {
+        try {
+            new ComposerWrapper(new ComposerWrapperParams());
+            new ComposerWrapper();
+            new ComposerWrapper(null);
+            $passed = true;
+        } catch (Exception $e) {
+            $passed = false;
+        }
+        self::assertTrue($passed);
+    }
+
+    /**
+     * @test
+     * @dataProvider invalidConstructorArguments
+     */
+    public function throwsOnInvalidParameters(array $args)
+    {
+        $this->expectExceptionMessageCompat(
+            'InvalidArgumentException',
+            'ComposerWrapper class can only be instantiated with ComposerWrapperParams object'
+        );
+        $class = new ReflectionClass('ComposerWrapper');
+        $class->newInstanceArgs($args);
+    }
+
+    public static function invalidConstructorArguments()
+    {
+        return array(
+            array(array('test')),
+            array(array(new \stdClass())),
+            array(array(true)),
+            array(array(false)),
+            array(array(123)),
+            array(array(123.45)),
+        );
+    }
+
     /**
      * @test
      */
@@ -386,7 +428,7 @@ public function selfUpdateWorks()
             ->willReturnCallback(function ($command, &$exitCode) { $exitCode = 0; });
 
         self::callNonPublic($wrapper, 'selfUpdate', array($file->url()));
-        clearstatcache(null, $file->url());
+        clearstatcache(true, $file->url());
         $this->assertGreaterThanOrEqual($now->getTimestamp(), filemtime($file->url()));
     }
 
@@ -555,7 +597,9 @@ public function passThroughWrapperWorksWithReferences()
         $exitCode = null;
         $class = new ReflectionClass($wrapper);
         $method = $class->getMethod('passthru');
-        $method->setAccessible(true);
+        if (PHP_VERSION_ID < 80500) {
+            $method->setAccessible(true);
+        }
         $method->invokeArgs(
             $wrapper,
             array(
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 8d5cfbf..e4cd03c 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -3,6 +3,32 @@
 require __DIR__ . '/BaseTestCase.php';
 
 // output buffer manipulations to get rid of shebang (#!/usr/bin/env php)
+$bootstrapFailureMessages = array();
+
+set_error_handler(function ($severity, $message, $file, $line) use (&$bootstrapFailureMessages) {
+    $bootstrapFailureMessages[] = sprintf('PHP Error: %s in %s:%d', $message, $file, $line);
+
+    return true;
+});
+
+set_exception_handler(function ($exception) use (&$bootstrapFailureMessages) {
+    $bootstrapFailureMessages[] = sprintf(
+        'Uncaught %s: %s in %s:%d',
+        get_class($exception),
+        $exception->getMessage(),
+        $exception->getFile(),
+        $exception->getLine()
+    );
+});
+
 ob_start();
 require __DIR__ . '/../composer';
 ob_end_clean();
+
+restore_exception_handler();
+restore_error_handler();
+
+if (!empty($bootstrapFailureMessages)) {
+    fwrite(STDERR, implode(PHP_EOL, $bootstrapFailureMessages) . PHP_EOL);
+    exit(1);
+}