diff --git a/tests/unit/widgets/AlertTest.php b/tests/unit/widgets/AlertTest.php
new file mode 100644
index 0000000..5a84cbd
--- /dev/null
+++ b/tests/unit/widgets/AlertTest.php
@@ -0,0 +1,261 @@
+<?php
+
+namespace tests\unit\widgets;
+
+use app\widgets\Alert;
+use Yii;
+
+class AlertTest extends \Codeception\Test\Unit
+{
+    public function testSingleErrorMessage()
+    {
+        $message = 'This is an error message';
+
+        Yii::$app->session->setFlash('error', $message);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($message);
+        expect($renderingResult)->stringContainsString('alert-danger');
+
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testMultipleErrorMessages()
+    {
+        $firstMessage = 'This is the first error message';
+        $secondMessage = 'This is the second error message';
+
+        Yii::$app->session->setFlash('error', [$firstMessage, $secondMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstMessage);
+        expect($renderingResult)->stringContainsString($secondMessage);
+        expect($renderingResult)->stringContainsString('alert-danger');
+
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testSingleDangerMessage()
+    {
+        $message = 'This is a danger message';
+
+        Yii::$app->session->setFlash('danger', $message);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($message);
+        expect($renderingResult)->stringContainsString('alert-danger');
+
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testMultipleDangerMessages()
+    {
+        $firstMessage = 'This is the first danger message';
+        $secondMessage = 'This is the second danger message';
+
+        Yii::$app->session->setFlash('danger', [$firstMessage, $secondMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstMessage);
+        expect($renderingResult)->stringContainsString($secondMessage);
+        expect($renderingResult)->stringContainsString('alert-danger');
+
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testSingleSuccessMessage()
+    {
+        $message = 'This is a success message';
+
+        Yii::$app->session->setFlash('success', $message);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($message);
+        expect($renderingResult)->stringContainsString('alert-success');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testMultipleSuccessMessages()
+    {
+        $firstMessage = 'This is the first danger message';
+        $secondMessage = 'This is the second danger message';
+
+        Yii::$app->session->setFlash('success', [$firstMessage, $secondMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstMessage);
+        expect($renderingResult)->stringContainsString($secondMessage);
+        expect($renderingResult)->stringContainsString('alert-success');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testSingleInfoMessage()
+    {
+        $message = 'This is an info message';
+
+        Yii::$app->session->setFlash('info', $message);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($message);
+        expect($renderingResult)->stringContainsString('alert-info');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testMultipleInfoMessages()
+    {
+        $firstMessage = 'This is the first info message';
+        $secondMessage = 'This is the second info message';
+
+        Yii::$app->session->setFlash('info', [$firstMessage, $secondMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstMessage);
+        expect($renderingResult)->stringContainsString($secondMessage);
+        expect($renderingResult)->stringContainsString('alert-info');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-warning');
+    }
+
+    public function testSingleWarningMessage()
+    {
+        $message = 'This is a warning message';
+
+        Yii::$app->session->setFlash('warning', $message);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($message);
+        expect($renderingResult)->stringContainsString('alert-warning');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+    }
+
+    public function testMultipleWarningMessages()
+    {
+        $firstMessage = 'This is the first warning message';
+        $secondMessage = 'This is the second warning message';
+
+        Yii::$app->session->setFlash('warning', [$firstMessage, $secondMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstMessage);
+        expect($renderingResult)->stringContainsString($secondMessage);
+        expect($renderingResult)->stringContainsString('alert-warning');
+
+        expect($renderingResult)->stringNotContainsString('alert-danger');
+        expect($renderingResult)->stringNotContainsString('alert-success');
+        expect($renderingResult)->stringNotContainsString('alert-info');
+    }
+
+    public function testSingleMixedMessages() {
+        $errorMessage = 'This is an error message';
+        $dangerMessage = 'This is a danger message';
+        $successMessage = 'This is a success message';
+        $infoMessage = 'This is a info message';
+        $warningMessage = 'This is a warning message';
+
+        Yii::$app->session->setFlash('error', $errorMessage);
+        Yii::$app->session->setFlash('danger', $dangerMessage);
+        Yii::$app->session->setFlash('success', $successMessage);
+        Yii::$app->session->setFlash('info', $infoMessage);
+        Yii::$app->session->setFlash('warning', $warningMessage);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($errorMessage);
+        expect($renderingResult)->stringContainsString($dangerMessage);
+        expect($renderingResult)->stringContainsString($successMessage);
+        expect($renderingResult)->stringContainsString($infoMessage);
+        expect($renderingResult)->stringContainsString($warningMessage);
+
+        expect($renderingResult)->stringContainsString('alert-danger');
+        expect($renderingResult)->stringContainsString('alert-success');
+        expect($renderingResult)->stringContainsString('alert-info');
+        expect($renderingResult)->stringContainsString('alert-warning');
+    }
+
+    public function testMultipleMixedMessages() {
+        $firstErrorMessage = 'This is the first error message';
+        $secondErrorMessage = 'This is the second error message';
+        $firstDangerMessage = 'This is the first danger message';
+        $secondDangerMessage = 'This is the second';
+        $firstSuccessMessage = 'This is the first success message';
+        $secondSuccessMessage = 'This is the second success message';
+        $firstInfoMessage = 'This is the first info message';
+        $secondInfoMessage = 'This is the second info message';
+        $firstWarningMessage = 'This is the first warning message';
+        $secondWarningMessage = 'This is the second warning message';
+
+        Yii::$app->session->setFlash('error', [$firstErrorMessage, $secondErrorMessage]);
+        Yii::$app->session->setFlash('danger', [$firstDangerMessage, $secondDangerMessage]);
+        Yii::$app->session->setFlash('success', [$firstSuccessMessage, $secondSuccessMessage]);
+        Yii::$app->session->setFlash('info', [$firstInfoMessage, $secondInfoMessage]);
+        Yii::$app->session->setFlash('warning', [$firstWarningMessage, $secondWarningMessage]);
+
+        $renderingResult = Alert::widget();
+
+        expect($renderingResult)->stringContainsString($firstErrorMessage);
+        expect($renderingResult)->stringContainsString($secondErrorMessage);
+        expect($renderingResult)->stringContainsString($firstDangerMessage);
+        expect($renderingResult)->stringContainsString($secondDangerMessage);
+        expect($renderingResult)->stringContainsString($firstSuccessMessage);
+        expect($renderingResult)->stringContainsString($secondSuccessMessage);
+        expect($renderingResult)->stringContainsString($firstInfoMessage);
+        expect($renderingResult)->stringContainsString($secondInfoMessage);
+        expect($renderingResult)->stringContainsString($firstWarningMessage);
+        expect($renderingResult)->stringContainsString($secondWarningMessage);
+
+        expect($renderingResult)->stringContainsString('alert-danger');
+        expect($renderingResult)->stringContainsString('alert-success');
+        expect($renderingResult)->stringContainsString('alert-info');
+        expect($renderingResult)->stringContainsString('alert-warning');
+    }
+
+    public function testFlashIntegrity()
+    {
+        $errorMessage = 'This is an error message';
+        $unrelatedMessage = 'This is a message that is not related to the alert widget';
+
+        Yii::$app->session->setFlash('error', $errorMessage);
+        Yii::$app->session->setFlash('unrelated', $unrelatedMessage);
+
+        Alert::widget();
+
+        // Simulate redirect
+        Yii::$app->session->close();
+        Yii::$app->session->open();
+
+        expect(Yii::$app->session->getFlash('error'))->null();
+        expect(Yii::$app->session->getFlash('unrelated'))->equals($unrelatedMessage);
+    }
+}
diff --git a/widgets/Alert.php b/widgets/Alert.php
index 9fbc739..fd2b195 100644
--- a/widgets/Alert.php
+++ b/widgets/Alert.php
@@ -51,13 +51,10 @@ class Alert extends \yii\bootstrap4\Widget
     public function run()
     {
         $session = Yii::$app->session;
-        $flashes = $session->getAllFlashes();
         $appendClass = isset($this->options['class']) ? ' ' . $this->options['class'] : '';
 
-        foreach ($flashes as $type => $flash) {
-            if (!isset($this->alertTypes[$type])) {
-                continue;
-            }
+        foreach (array_keys($this->alertTypes) as $type) {
+            $flash = $session->getFlash($type);
 
             foreach ((array) $flash as $i => $message) {
                 echo \yii\bootstrap4\Alert::widget([