diff --git a/README.md b/README.md
index c5e349f..6bbd7fe 100644
--- a/README.md
+++ b/README.md
@@ -346,14 +346,14 @@ final class Alert
 
 <br>
 
-### PublicPropertiesShouldBeCamelCaseRule
+### PostMountMethodSignatureRule
 
-Enforces that all public properties in Twig Components follow camelCase naming convention.
-This ensures consistency and better integration with Twig templates where properties are passed and accessed using camelCase.
+Enforces that methods with the `#[PostMount]` attribute have the correct signature: they must be public with an optional parameter of type `array`, and a return type of `array`, `void`, or `array|void`.
+This ensures proper integration with the Symfony UX TwigComponent lifecycle hooks.
 
 ```yaml
 rules:
-    - Kocal\PHPStanSymfonyUX\Rules\TwigComponent\PublicPropertiesShouldBeCamelCaseRule
+    - Kocal\PHPStanSymfonyUX\Rules\TwigComponent\PostMountMethodSignatureRule
 ```
 
 ```php
@@ -361,12 +361,15 @@ rules:
 namespace App\Twig\Components;
 
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
 
 #[AsTwigComponent]
 final class Alert
 {
-    public string $user_name;
-    public bool $is_active;
+    #[PostMount]
+    protected function postMount(): void
+    {
+    }
 }
 ```
 
@@ -375,11 +378,33 @@ final class Alert
 namespace App\Twig\Components;
 
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
 
 #[AsTwigComponent]
 final class Alert
 {
-    public string $UserName;
+    #[PostMount]
+    public function postMount(array $data): string
+    {
+        return 'invalid';
+    }
+}
+```
+
+```php
+// src/Twig/Components/Alert.php
+namespace App\Twig\Components;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class Alert
+{
+    #[PostMount]
+    public function postMount(string $data): void
+    {
+    }
 }
 ```
 
@@ -392,12 +417,33 @@ final class Alert
 namespace App\Twig\Components;
 
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
 
 #[AsTwigComponent]
 final class Alert
 {
-    public string $userName;
-    public bool $isActive;
+    #[PostMount]
+    public function postMount(): void
+    {
+    }
+}
+```
+
+```php
+// src/Twig/Components/Alert.php
+namespace App\Twig\Components;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class Alert
+{
+    #[PostMount]
+    public function postMount(array $data): array
+    {
+        return $data;
+    }
 }
 ```
 
@@ -407,7 +453,7 @@ final class Alert
 
 ### PreMountMethodSignatureRule
 
-Enforces that methods with the `#[PreMount]` attribute have the correct signature: they must be public and have exactly one parameter of type `array`, with a return type of `array`.
+Enforces that methods with the `#[PreMount]` attribute have the correct signature: they must be public and have exactly one parameter of type `array`, with a return type of `array`, `void`, or `array|void` .
 This ensures proper integration with the Symfony UX TwigComponent lifecycle hooks.
 
 ```yaml
@@ -444,12 +490,17 @@ use Symfony\UX\TwigComponent\Attribute\PreMount;
 final class Alert
 {
     #[PreMount]
-    public function preMount(array $data): void
+    public function preMount(string $data): array
     {
+        return [];
     }
 }
 ```
 
+:x:
+
+<br>
+
 ```php
 // src/Twig/Components/Alert.php
 namespace App\Twig\Components;
@@ -461,34 +512,71 @@ use Symfony\UX\TwigComponent\Attribute\PreMount;
 final class Alert
 {
     #[PreMount]
-    public function preMount(string $data): array
+    public function preMount(array $data): array
     {
-        return [];
+        $data['timestamp'] = time();
+
+        return $data;
     }
 }
 ```
 
-:x:
+:+1:
 
 <br>
 
+### PublicPropertiesShouldBeCamelCaseRule
+
+Enforces that all public properties in Twig Components follow camelCase naming convention.
+This ensures consistency and better integration with Twig templates where properties are passed and accessed using camelCase.
+
+```yaml
+rules:
+    - Kocal\PHPStanSymfonyUX\Rules\TwigComponent\PublicPropertiesShouldBeCamelCaseRule
+```
+
 ```php
 // src/Twig/Components/Alert.php
 namespace App\Twig\Components;
 
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
-use Symfony\UX\TwigComponent\Attribute\PreMount;
 
 #[AsTwigComponent]
 final class Alert
 {
-    #[PreMount]
-    public function preMount(array $data): array
-    {
-        $data['timestamp'] = time();
+    public string $user_name;
+    public bool $is_active;
+}
+```
 
-        return $data;
-    }
+```php
+// src/Twig/Components/Alert.php
+namespace App\Twig\Components;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+
+#[AsTwigComponent]
+final class Alert
+{
+    public string $UserName;
+}
+```
+
+:x:
+
+<br>
+
+```php
+// src/Twig/Components/Alert.php
+namespace App\Twig\Components;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+
+#[AsTwigComponent]
+final class Alert
+{
+    public string $userName;
+    public bool $isActive;
 }
 ```
 
diff --git a/ecs.php b/ecs.php
index 7f24063..09033eb 100644
--- a/ecs.php
+++ b/ecs.php
@@ -14,7 +14,7 @@
     ->withPreparedSets(psr12: true, common: true)
     ->withSkip([
         ProtectedToPrivateFixer::class => [
-            __DIR__ . '/tests/Rules/TwigComponent/MethodsShouldBePublicOrPrivateRule/Fixture/*',
+            __DIR__ . '/tests/Rules/**/Fixture/*',
         ],
     ])
 ;
diff --git a/phpstan.dist.neon b/phpstan.dist.neon
index e786f4c..053d645 100644
--- a/phpstan.dist.neon
+++ b/phpstan.dist.neon
@@ -12,6 +12,4 @@ parameters:
             identifiers:
                 - method.unused
                 - missingType.iterableValue
-                - missingType.return
                 - property.unused
-                - return.unusedType
\ No newline at end of file
diff --git a/src/Rules/TwigComponent/PostMountMethodSignatureRule.php b/src/Rules/TwigComponent/PostMountMethodSignatureRule.php
new file mode 100644
index 0000000..7623153
--- /dev/null
+++ b/src/Rules/TwigComponent/PostMountMethodSignatureRule.php
@@ -0,0 +1,114 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Rules\TwigComponent;
+
+use Kocal\PHPStanSymfonyUX\NodeAnalyzer\AttributeFinder;
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Class_;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\ExtendedMethodReflection;
+use PHPStan\Reflection\ReflectionProvider;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+/**
+ * @implements Rule<Class_>
+ */
+final class PostMountMethodSignatureRule implements Rule
+{
+    public function __construct(
+        private ReflectionProvider $reflectionProvider,
+    ) {
+    }
+
+    public function getNodeType(): string
+    {
+        return Class_::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (! AttributeFinder::findAnyAttribute($node, [AsTwigComponent::class, AsLiveComponent::class])) {
+            return [];
+        }
+
+        if ($node->namespacedName === null) {
+            return [];
+        }
+
+        $errors = [];
+        $reflClass = $this->reflectionProvider->getClass($node->namespacedName->toString());
+
+        foreach ($node->getMethods() as $method) {
+            if (! AttributeFinder::findAttribute($method, PostMount::class)) {
+                continue;
+            }
+
+            $errors[] = $this->validatePostMountMethod(
+                $method,
+                $reflClass->getMethod($method->name->name, $scope),
+            );
+        }
+
+        return array_merge(...$errors);
+    }
+
+    /**
+     * @return list<\PHPStan\Rules\IdentifierRuleError>
+     */
+    private function validatePostMountMethod(Node\Stmt\ClassMethod $method, ExtendedMethodReflection $reflMethod): array
+    {
+        $errors = [];
+
+        $methodName = $reflMethod->getName();
+        $methodParams = $reflMethod->getOnlyVariant()->getParameters();
+        $methodReturnType = $reflMethod->getOnlyVariant()->getReturnType();
+
+        // Check if method is public
+        if (! $reflMethod->isPublic()) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PostMount] attribute must be public.', $methodName))
+                ->identifier('symfonyUX.twigComponent.postMountPublic')
+                ->line($method->getLine())
+                ->tip('Change the method visibility to public.')
+                ->build();
+        }
+
+        // Check parameter count and type (0 or 1 parameter allowed)
+        if (count($methodParams) > 1) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PostMount] attribute must have at most one parameter of type "array".', $methodName))
+                ->identifier('symfonyUX.twigComponent.postMountParameterCount')
+                ->line($method->getLine())
+                ->tip('The method should have zero or one parameter: "array $data" (optional).')
+                ->build();
+        } elseif (count($methodParams) === 1) {
+            // If there is a parameter, it must be of type array
+            if (! $methodParams[0]->getType()->isArray()->yes()) {
+                $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PostMount] attribute must have a parameter of type "array".', $methodName))
+                    ->identifier('symfonyUX.twigComponent.postMountParameterType')
+                    ->line($method->getLine())
+                    ->tip('Change the parameter type to "array".')
+                    ->build();
+            }
+        }
+
+        // Check return type (must be array, void, or array|void)
+        $isValidReturnType = $methodReturnType->isVoid()->yes()
+            || $methodReturnType->isArray()->yes()
+            || ($methodReturnType->isArray()->maybe() && $methodReturnType->isVoid()->maybe());
+
+        if (! $isValidReturnType) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PostMount] attribute must have a return type of "array", "void", or "array|void".', $methodName))
+                ->identifier('symfonyUX.twigComponent.postMountReturnType')
+                ->line($method->getLine())
+                ->tip('Change the return type to ": array", ": void", or ": array|void".')
+                ->build();
+        }
+
+        return $errors;
+    }
+}
diff --git a/src/Rules/TwigComponent/PreMountMethodSignatureRule.php b/src/Rules/TwigComponent/PreMountMethodSignatureRule.php
index 4543c34..2223865 100644
--- a/src/Rules/TwigComponent/PreMountMethodSignatureRule.php
+++ b/src/Rules/TwigComponent/PreMountMethodSignatureRule.php
@@ -8,6 +8,8 @@
 use PhpParser\Node;
 use PhpParser\Node\Stmt\Class_;
 use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\ExtendedMethodReflection;
+use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
@@ -19,6 +21,11 @@
  */
 final class PreMountMethodSignatureRule implements Rule
 {
+    public function __construct(
+        private ReflectionProvider $reflectionProvider,
+    ) {
+    }
+
     public function getNodeType(): string
     {
         return Class_::class;
@@ -30,84 +37,76 @@ public function processNode(Node $node, Scope $scope): array
             return [];
         }
 
+        if ($node->namespacedName === null) {
+            return [];
+        }
+
         $errors = [];
+        $reflClass = $this->reflectionProvider->getClass($node->namespacedName->toString());
 
         foreach ($node->getMethods() as $method) {
-            // Check if the method has the PreMount attribute
             if (! AttributeFinder::findAttribute($method, PreMount::class)) {
                 continue;
             }
 
-            $errors = array_merge($errors, $this->validatePreMountMethod($method));
+            $errors[] = $this->validatePreMountMethod(
+                $method,
+                $reflClass->getMethod($method->name->name, $scope),
+            );
         }
 
-        return $errors;
+        return array_merge(...$errors);
     }
 
     /**
      * @return list<\PHPStan\Rules\IdentifierRuleError>
      */
-    private function validatePreMountMethod(Node\Stmt\ClassMethod $node): array
+    private function validatePreMountMethod(Node\Stmt\ClassMethod $method, ExtendedMethodReflection $reflMethod): array
     {
         $errors = [];
 
-        // Check if the method is public
-        if (! $node->isPublic()) {
-            $errors[] = RuleErrorBuilder::message(
-                sprintf('Method "%s" with #[PreMount] attribute must be public.', $node->name->toString())
-            )
-                ->identifier('symfonyUX.twigComponent.preMountMethodMustBePublic')
-                ->line($node->getLine())
+        $methodName = $reflMethod->getName();
+        $methodParams = $reflMethod->getOnlyVariant()->getParameters();
+        $methodReturnType = $reflMethod->getOnlyVariant()->getReturnType();
+
+        // Check if method is public
+        if (! $reflMethod->isPublic()) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PreMount] attribute must be public.', $methodName))
+                ->identifier('symfonyUX.twigComponent.preMountPublic')
+                ->line($method->getLine())
                 ->tip('Change the method visibility to public.')
                 ->build();
         }
 
-        // Check the return type
-        $returnType = $node->getReturnType();
-        if ($returnType === null) {
-            $errors[] = RuleErrorBuilder::message(
-                sprintf('Method "%s" with #[PreMount] attribute must have a return type of "array".', $node->name->toString())
-            )
-                ->identifier('symfonyUX.twigComponent.preMountMethodMissingReturnType')
-                ->line($node->getLine())
-                ->tip('Add ": array" return type to the method.')
+        // Check parameter count and type (0 or 1 parameter allowed)
+        if (count($methodParams) > 1) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PreMount] attribute must have at most one parameter of type "array".', $methodName))
+                ->identifier('symfonyUX.twigComponent.preMountParameterCount')
+                ->line($method->getLine())
+                ->tip('The method should have zero or one parameter: "array $data" (optional).')
                 ->build();
-        } else {
-            $isValidReturnType = $returnType instanceof Node\Identifier && $returnType->toString() === 'array';
-
-            if (! $isValidReturnType) {
-                $errors[] = RuleErrorBuilder::message(
-                    sprintf('Method "%s" with #[PreMount] attribute must have a return type of "array".', $node->name->toString())
-                )
-                    ->identifier('symfonyUX.twigComponent.preMountMethodInvalidReturnType')
-                    ->line($returnType->getLine())
-                    ->tip('Change the return type to ": array".')
+        } elseif (count($methodParams) === 1) {
+            // If there is a parameter, it must be of type array
+            if (! $methodParams[0]->getType()->isArray()->yes()) {
+                $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PreMount] attribute must have a parameter of type "array".', $methodName))
+                    ->identifier('symfonyUX.twigComponent.preMountParameterType')
+                    ->line($method->getLine())
+                    ->tip('Change the parameter type to "array".')
                     ->build();
             }
         }
 
-        // Check that there is exactly one parameter of type array
-        if (count($node->params) !== 1) {
-            $errors[] = RuleErrorBuilder::message(
-                sprintf('Method "%s" with #[PreMount] attribute must have exactly one parameter of type "array".', $node->name->toString())
-            )
-                ->identifier('symfonyUX.twigComponent.preMountMethodInvalidParameterCount')
-                ->line($node->getLine())
-                ->tip('The method should have exactly one parameter: "array $data".')
+        // Check return type (must be array, void, or array|void)
+        $isValidReturnType = $methodReturnType->isVoid()->yes()
+            || $methodReturnType->isArray()->yes()
+            || ($methodReturnType->isArray()->maybe() && $methodReturnType->isVoid()->maybe());
+
+        if (! $isValidReturnType) {
+            $errors[] = RuleErrorBuilder::message(sprintf('Method "%s" with #[PreMount] attribute must have a return type of "array", "void", or "array|void".', $methodName))
+                ->identifier('symfonyUX.twigComponent.preMountReturnType')
+                ->line($method->getLine())
+                ->tip('Change the return type to ": array", ": void", or ": array|void".')
                 ->build();
-        } else {
-            $param = $node->params[0];
-            $paramType = $param->type;
-
-            if (! $paramType instanceof Node\Identifier || $paramType->toString() !== 'array') {
-                $errors[] = RuleErrorBuilder::message(
-                    sprintf('Method "%s" with #[PreMount] attribute must have a parameter of type "array".', $node->name->toString())
-                )
-                    ->identifier('symfonyUX.twigComponent.preMountMethodInvalidParameterType')
-                    ->line($param->getLine())
-                    ->tip('Change the parameter type to "array".')
-                    ->build();
-            }
         }
 
         return $errors;
diff --git a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/ClassNameShouldNotEndWithComponentRuleTest.php b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/ClassNameShouldNotEndWithComponentRuleTest.php
index 52200fd..249fee2 100644
--- a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/ClassNameShouldNotEndWithComponentRuleTest.php
+++ b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/ClassNameShouldNotEndWithComponentRuleTest.php
@@ -16,7 +16,7 @@ final class ClassNameShouldNotEndWithComponentRuleTest extends RuleTestCase
     public function testViolations(): void
     {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidComponentName.php'],
+            [__DIR__ . '/Fixture/AlertComponent.php'],
             [
                 [
                     'Twig component class "AlertComponent" should not end with "Component".',
@@ -27,7 +27,7 @@ public function testViolations(): void
         );
 
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidLiveComponentName.php'],
+            [__DIR__ . '/Fixture/CounterComponent.php'],
             [
                 [
                     'Twig component class "CounterComponent" should not end with "Component".',
diff --git a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/InvalidComponentName.php b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/AlertComponent.php
similarity index 100%
rename from tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/InvalidComponentName.php
rename to tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/AlertComponent.php
diff --git a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/InvalidLiveComponentName.php b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/CounterComponent.php
similarity index 100%
rename from tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/InvalidLiveComponentName.php
rename to tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/CounterComponent.php
diff --git a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidComponentName.php b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidComponentName.php
index 15428a5..f654774 100644
--- a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidComponentName.php
+++ b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidComponentName.php
@@ -7,6 +7,6 @@
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
 
 #[AsTwigComponent]
-final class Alert
+final class ValidComponentName
 {
 }
diff --git a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidLiveComponentName.php b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidLiveComponentName.php
index ec1a72f..d871198 100644
--- a/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidLiveComponentName.php
+++ b/tests/Rules/TwigComponent/ClassNameShouldNotEndWithComponentRule/Fixture/ValidLiveComponentName.php
@@ -7,6 +7,6 @@
 use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
 
 #[AsLiveComponent]
-final class Counter
+final class ValidLiveComponentName
 {
 }
diff --git a/tests/Rules/TwigComponent/ForbiddenAttributesPropertyRule/Fixture/ComponentWithCustomAttributesProperty.php b/tests/Rules/TwigComponent/ForbiddenAttributesPropertyRule/Fixture/ComponentWithCustomAttributesProperty.php
index 8fc7fea..14b5665 100644
--- a/tests/Rules/TwigComponent/ForbiddenAttributesPropertyRule/Fixture/ComponentWithCustomAttributesProperty.php
+++ b/tests/Rules/TwigComponent/ForbiddenAttributesPropertyRule/Fixture/ComponentWithCustomAttributesProperty.php
@@ -7,7 +7,7 @@
 use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
 
 #[AsTwigComponent(attributesVar: 'customAttributes')]
-final class ComponentWithAttributesProperty
+final class ComponentWithCustomAttributesProperty
 {
     public string $customAttributes;
 }
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidLiveComponent.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidLiveComponent.php
new file mode 100644
index 0000000..bf1f56b
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidLiveComponent.php
@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsLiveComponent]
+final class InvalidLiveComponent
+{
+    #[PostMount]
+    public function postMountWrongType(string $data): void
+    {
+    }
+
+    #[PostMount]
+    public function postMountWrongReturn(): string
+    {
+        return '';
+    }
+
+    #[PostMount]
+    private function postMountPrivate(): void
+    {
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterCount.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterCount.php
new file mode 100644
index 0000000..0d168fa
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterCount.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class InvalidParameterCount
+{
+    #[PostMount]
+    public function postMountTooManyParams(array $data, array $extra): void
+    {
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterType.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterType.php
new file mode 100644
index 0000000..d35e5b1
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidParameterType.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class InvalidParameterType
+{
+    #[PostMount]
+    public function postMountWrongType(string $data): void
+    {
+    }
+
+    #[PostMount]
+    public function postMountIntType(int $data): void
+    {
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidReturnType.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidReturnType.php
new file mode 100644
index 0000000..ec36709
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidReturnType.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class InvalidReturnType
+{
+    #[PostMount]
+    public function postMountStringReturn(): string
+    {
+        return '';
+    }
+
+    #[PostMount]
+    public function postMountIntReturn(): int
+    {
+        return 0;
+    }
+
+    #[PostMount]
+    public function postMountBoolReturn(): bool
+    {
+        return true;
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidVisibility.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidVisibility.php
new file mode 100644
index 0000000..d0aa47d
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/InvalidVisibility.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class InvalidVisibility
+{
+    #[PostMount]
+    protected function postMountProtected(): void
+    {
+    }
+
+    #[PostMount]
+    private function postMountPrivate(): void
+    {
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/NotAComponent.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/NotAComponent.php
new file mode 100644
index 0000000..57abadb
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/NotAComponent.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+final class NotAComponent
+{
+    #[PostMount]
+    private function postMount(string $data): string
+    {
+        return '';
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidLiveComponent.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidLiveComponent.php
new file mode 100644
index 0000000..f4fe7cb
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidLiveComponent.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsLiveComponent]
+final class ValidLiveComponent
+{
+    // Valid: public, no parameters, returns void
+    #[PostMount]
+    public function postMount1(): void
+    {
+    }
+
+    // Valid: public, array parameter, returns void
+    #[PostMount]
+    public function postMount2(array $data): void
+    {
+    }
+
+    // Valid: public, no parameters, returns array
+    #[PostMount]
+    public function postMount3(): array
+    {
+        return [];
+    }
+
+    // Valid: public, array parameter, returns array
+    #[PostMount]
+    public function postMount4(array $data): array
+    {
+        return [];
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidTwigComponent.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidTwigComponent.php
new file mode 100644
index 0000000..4f031e8
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/Fixture/ValidTwigComponent.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PostMount;
+
+#[AsTwigComponent]
+final class ValidTwigComponent
+{
+    // Valid: public, no parameters, returns void
+    #[PostMount]
+    public function postMount1(): void
+    {
+    }
+
+    // Valid: public, array parameter, returns void
+    #[PostMount]
+    public function postMount2(array $data): void
+    {
+    }
+
+    // Valid: public, no parameters, returns array
+    #[PostMount]
+    public function postMount3(): array
+    {
+        return [];
+    }
+
+    // Valid: public, array parameter, returns array
+    #[PostMount]
+    public function postMount4(array $data): array
+    {
+        return [];
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/PostMountMethodSignatureRuleTest.php b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/PostMountMethodSignatureRuleTest.php
new file mode 100644
index 0000000..db93c62
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/PostMountMethodSignatureRuleTest.php
@@ -0,0 +1,143 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PostMountMethodSignatureRule;
+
+use Kocal\PHPStanSymfonyUX\Rules\TwigComponent\PostMountMethodSignatureRule;
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<PostMountMethodSignatureRule>
+ */
+final class PostMountMethodSignatureRuleTest extends RuleTestCase
+{
+    public function testInvalidVisibility(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/InvalidVisibility.php'],
+            [
+                [
+                    'Method "postMountProtected" with #[PostMount] attribute must be public.',
+                    13,
+                    'Change the method visibility to public.',
+                ],
+                [
+                    'Method "postMountPrivate" with #[PostMount] attribute must be public.',
+                    18,
+                    'Change the method visibility to public.',
+                ],
+            ]
+        );
+    }
+
+    public function testInvalidParameterCount(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/InvalidParameterCount.php'],
+            [
+                [
+                    'Method "postMountTooManyParams" with #[PostMount] attribute must have at most one parameter of type "array".',
+                    13,
+                    'The method should have zero or one parameter: "array $data" (optional).',
+                ],
+            ]
+        );
+    }
+
+    public function testInvalidParameterType(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/InvalidParameterType.php'],
+            [
+                [
+                    'Method "postMountWrongType" with #[PostMount] attribute must have a parameter of type "array".',
+                    13,
+                    'Change the parameter type to "array".',
+                ],
+                [
+                    'Method "postMountIntType" with #[PostMount] attribute must have a parameter of type "array".',
+                    18,
+                    'Change the parameter type to "array".',
+                ],
+            ]
+        );
+    }
+
+    public function testInvalidReturnType(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/InvalidReturnType.php'],
+            [
+                [
+                    'Method "postMountStringReturn" with #[PostMount] attribute must have a return type of "array", "void", or "array|void".',
+                    13,
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+                [
+                    'Method "postMountIntReturn" with #[PostMount] attribute must have a return type of "array", "void", or "array|void".',
+                    19,
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+                [
+                    'Method "postMountBoolReturn" with #[PostMount] attribute must have a return type of "array", "void", or "array|void".',
+                    25,
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+            ]
+        );
+    }
+
+    public function testInvalidLiveComponent(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/InvalidLiveComponent.php'],
+            [
+                [
+                    'Method "postMountWrongType" with #[PostMount] attribute must have a parameter of type "array".',
+                    13,
+                    'Change the parameter type to "array".',
+                ],
+                [
+                    'Method "postMountWrongReturn" with #[PostMount] attribute must have a return type of "array", "void", or "array|void".',
+                    18,
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+                [
+                    'Method "postMountPrivate" with #[PostMount] attribute must be public.',
+                    24,
+                    'Change the method visibility to public.',
+                ],
+            ]
+        );
+    }
+
+    public function testNoViolations(): void
+    {
+        $this->analyse(
+            [__DIR__ . '/Fixture/NotAComponent.php'],
+            []
+        );
+
+        $this->analyse(
+            [__DIR__ . '/Fixture/ValidTwigComponent.php'],
+            []
+        );
+
+        $this->analyse(
+            [__DIR__ . '/Fixture/ValidLiveComponent.php'],
+            []
+        );
+    }
+
+    public static function getAdditionalConfigFiles(): array
+    {
+        return [__DIR__ . '/config/configured_rule.neon'];
+    }
+
+    protected function getRule(): Rule
+    {
+        return self::getContainer()->getByType(PostMountMethodSignatureRule::class);
+    }
+}
diff --git a/tests/Rules/TwigComponent/PostMountMethodSignatureRule/config/configured_rule.neon b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/config/configured_rule.neon
new file mode 100644
index 0000000..620095f
--- /dev/null
+++ b/tests/Rules/TwigComponent/PostMountMethodSignatureRule/config/configured_rule.neon
@@ -0,0 +1,2 @@
+rules:
+    - Kocal\PHPStanSymfonyUX\Rules\TwigComponent\PostMountMethodSignatureRule
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidLiveComponent.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidLiveComponent.php
new file mode 100644
index 0000000..8576b7f
--- /dev/null
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidLiveComponent.php
@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
+use Symfony\UX\TwigComponent\Attribute\PreMount;
+
+#[AsLiveComponent]
+final class InvalidLiveComponent
+{
+    #[PreMount]
+    public function preMountWrongType(string $data): void
+    {
+    }
+
+    #[PreMount]
+    public function preMountWrongReturn(): string
+    {
+        return '';
+    }
+
+    #[PreMount]
+    private function preMountPrivate(): void
+    {
+    }
+}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoParameter.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterCount.php
similarity index 72%
rename from tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoParameter.php
rename to tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterCount.php
index 301e101..c60425c 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoParameter.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterCount.php
@@ -8,11 +8,10 @@
 use Symfony\UX\TwigComponent\Attribute\PreMount;
 
 #[AsTwigComponent]
-final class InvalidNoParameter
+final class InvalidParameterCount
 {
     #[PreMount]
-    public function preMount(): array
+    public function preMountTooManyParams(array $data, array $extra): void
     {
-        return [];
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNotPublic.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterType.php
similarity index 62%
rename from tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNotPublic.php
rename to tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterType.php
index d47fff8..8a3ec15 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNotPublic.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidParameterType.php
@@ -8,11 +8,15 @@
 use Symfony\UX\TwigComponent\Attribute\PreMount;
 
 #[AsTwigComponent]
-final class InvalidNotPublic
+final class InvalidParameterType
 {
     #[PreMount]
-    private function preMount(array $data): array
+    public function preMountWrongType(string $data): void
+    {
+    }
+
+    #[PreMount]
+    public function preMountIntType(int $data): void
     {
-        return $data;
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidReturnType.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidReturnType.php
new file mode 100644
index 0000000..25f6923
--- /dev/null
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidReturnType.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
+
+use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
+use Symfony\UX\TwigComponent\Attribute\PreMount;
+
+#[AsTwigComponent]
+final class InvalidReturnType
+{
+    #[PreMount]
+    public function preMountStringReturn(): string
+    {
+        return '';
+    }
+
+    #[PreMount]
+    public function preMountIntReturn(): int
+    {
+        return 0;
+    }
+
+    #[PreMount]
+    public function preMountBoolReturn(): bool
+    {
+        return true;
+    }
+}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidTooManyParameters.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidTooManyParameters.php
deleted file mode 100644
index d568a93..0000000
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidTooManyParameters.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
-
-use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
-use Symfony\UX\TwigComponent\Attribute\PreMount;
-
-#[AsTwigComponent]
-final class InvalidTooManyParameters
-{
-    #[PreMount]
-    public function preMount(array $data, string $extra): array
-    {
-        return $data;
-    }
-}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoReturnType.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidVisibility.php
similarity index 65%
rename from tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoReturnType.php
rename to tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidVisibility.php
index 32c1717..7e8aac4 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidNoReturnType.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidVisibility.php
@@ -8,11 +8,15 @@
 use Symfony\UX\TwigComponent\Attribute\PreMount;
 
 #[AsTwigComponent]
-final class InvalidNoReturnType
+final class InvalidVisibility
 {
     #[PreMount]
-    public function preMount(array $data)
+    protected function preMountProtected(): void
+    {
+    }
+
+    #[PreMount]
+    private function preMountPrivate(): void
     {
-        return $data;
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWithNullableReturnType.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWithNullableReturnType.php
deleted file mode 100644
index 6d92be0..0000000
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWithNullableReturnType.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
-
-use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
-use Symfony\UX\TwigComponent\Attribute\PreMount;
-
-#[AsTwigComponent]
-final class InvalidWithNullableReturnType
-{
-    #[PreMount]
-    public function preMount(array $data): ?array
-    {
-        return $data;
-    }
-}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongParameterType.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongParameterType.php
deleted file mode 100644
index 6e5ab45..0000000
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongParameterType.php
+++ /dev/null
@@ -1,18 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
-
-use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
-use Symfony\UX\TwigComponent\Attribute\PreMount;
-
-#[AsTwigComponent]
-final class InvalidWrongParameterType
-{
-    #[PreMount]
-    public function preMount(string $data): array
-    {
-        return [];
-    }
-}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongReturnType.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongReturnType.php
deleted file mode 100644
index f60f940..0000000
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/InvalidWrongReturnType.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Kocal\PHPStanSymfonyUX\Tests\Rules\TwigComponent\PreMountMethodSignatureRule\Fixture;
-
-use Symfony\UX\TwigComponent\Attribute\AsTwigComponent;
-use Symfony\UX\TwigComponent\Attribute\PreMount;
-
-#[AsTwigComponent]
-final class InvalidWrongReturnType
-{
-    #[PreMount]
-    public function preMount(array $data): void
-    {
-    }
-}
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/NotAComponent.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/NotAComponent.php
index 02ab6c4..ca2fc8f 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/NotAComponent.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/NotAComponent.php
@@ -9,8 +9,8 @@
 final class NotAComponent
 {
     #[PreMount]
-    public function preMount(array $data): array
+    private function preMount(string $data): string
     {
-        return $data;
+        return '';
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidLiveComponent.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidLiveComponent.php
index a8a073f..1dde4da 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidLiveComponent.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidLiveComponent.php
@@ -10,9 +10,29 @@
 #[AsLiveComponent]
 final class ValidLiveComponent
 {
+    // Valid: public, no parameters, returns void
     #[PreMount]
-    public function preMount(array $data): array
+    public function preMount1(): void
     {
-        return $data;
+    }
+
+    // Valid: public, array parameter, returns void
+    #[PreMount]
+    public function preMount2(array $data): void
+    {
+    }
+
+    // Valid: public, no parameters, returns array
+    #[PreMount]
+    public function preMount3(): array
+    {
+        return [];
+    }
+
+    // Valid: public, array parameter, returns array
+    #[PreMount]
+    public function preMount4(array $data): array
+    {
+        return [];
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidTwigComponent.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidTwigComponent.php
index 5fee538..1ac8606 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidTwigComponent.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/Fixture/ValidTwigComponent.php
@@ -10,9 +10,29 @@
 #[AsTwigComponent]
 final class ValidTwigComponent
 {
+    // Valid: public, no parameters, returns void
     #[PreMount]
-    public function preMount(array $data): array
+    public function preMount1(): void
     {
-        return $data;
+    }
+
+    // Valid: public, array parameter, returns void
+    #[PreMount]
+    public function preMount2(array $data): void
+    {
+    }
+
+    // Valid: public, no parameters, returns array
+    #[PreMount]
+    public function preMount3(): array
+    {
+        return [];
+    }
+
+    // Valid: public, array parameter, returns array
+    #[PreMount]
+    public function preMount4(array $data): array
+    {
+        return [];
     }
 }
diff --git a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/PreMountMethodSignatureRuleTest.php b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/PreMountMethodSignatureRuleTest.php
index 1a654fc..09b154a 100644
--- a/tests/Rules/TwigComponent/PreMountMethodSignatureRule/PreMountMethodSignatureRuleTest.php
+++ b/tests/Rules/TwigComponent/PreMountMethodSignatureRule/PreMountMethodSignatureRuleTest.php
@@ -13,82 +13,102 @@
  */
 final class PreMountMethodSignatureRuleTest extends RuleTestCase
 {
-    public function testViolations(): void
+    public function testInvalidVisibility(): void
     {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidNotPublic.php'],
+            [__DIR__ . '/Fixture/InvalidVisibility.php'],
             [
                 [
-                    'Method "preMount" with #[PreMount] attribute must be public.',
+                    'Method "preMountProtected" with #[PreMount] attribute must be public.',
                     13,
                     'Change the method visibility to public.',
                 ],
-            ]
-        );
-
-        $this->analyse(
-            [__DIR__ . '/Fixture/InvalidNoReturnType.php'],
-            [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have a return type of "array".',
-                    13,
-                    'Add ": array" return type to the method.',
+                    'Method "preMountPrivate" with #[PreMount] attribute must be public.',
+                    18,
+                    'Change the method visibility to public.',
                 ],
             ]
         );
+    }
 
+    public function testInvalidParameterCount(): void
+    {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidWrongReturnType.php'],
+            [__DIR__ . '/Fixture/InvalidParameterCount.php'],
             [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have a return type of "array".',
-                    14,
-                    'Change the return type to ": array".',
+                    'Method "preMountTooManyParams" with #[PreMount] attribute must have at most one parameter of type "array".',
+                    13,
+                    'The method should have zero or one parameter: "array $data" (optional).',
                 ],
             ]
         );
+    }
 
+    public function testInvalidParameterType(): void
+    {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidNoParameter.php'],
+            [__DIR__ . '/Fixture/InvalidParameterType.php'],
             [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have exactly one parameter of type "array".',
+                    'Method "preMountWrongType" with #[PreMount] attribute must have a parameter of type "array".',
                     13,
-                    'The method should have exactly one parameter: "array $data".',
+                    'Change the parameter type to "array".',
+                ],
+                [
+                    'Method "preMountIntType" with #[PreMount] attribute must have a parameter of type "array".',
+                    18,
+                    'Change the parameter type to "array".',
                 ],
             ]
         );
+    }
 
+    public function testInvalidReturnType(): void
+    {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidTooManyParameters.php'],
+            [__DIR__ . '/Fixture/InvalidReturnType.php'],
             [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have exactly one parameter of type "array".',
+                    'Method "preMountStringReturn" with #[PreMount] attribute must have a return type of "array", "void", or "array|void".',
                     13,
-                    'The method should have exactly one parameter: "array $data".',
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+                [
+                    'Method "preMountIntReturn" with #[PreMount] attribute must have a return type of "array", "void", or "array|void".',
+                    19,
+                    'Change the return type to ": array", ": void", or ": array|void".',
                 ],
-            ]
-        );
-
-        $this->analyse(
-            [__DIR__ . '/Fixture/InvalidWithNullableReturnType.php'],
-            [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have a return type of "array".',
-                    14,
-                    'Change the return type to ": array".',
+                    'Method "preMountBoolReturn" with #[PreMount] attribute must have a return type of "array", "void", or "array|void".',
+                    25,
+                    'Change the return type to ": array", ": void", or ": array|void".',
                 ],
             ]
         );
+    }
 
+    public function testInvalidLiveComponent(): void
+    {
         $this->analyse(
-            [__DIR__ . '/Fixture/InvalidWrongParameterType.php'],
+            [__DIR__ . '/Fixture/InvalidLiveComponent.php'],
             [
                 [
-                    'Method "preMount" with #[PreMount] attribute must have a parameter of type "array".',
-                    14,
+                    'Method "preMountWrongType" with #[PreMount] attribute must have a parameter of type "array".',
+                    13,
                     'Change the parameter type to "array".',
                 ],
+                [
+                    'Method "preMountWrongReturn" with #[PreMount] attribute must have a return type of "array", "void", or "array|void".',
+                    18,
+                    'Change the return type to ": array", ": void", or ": array|void".',
+                ],
+                [
+                    'Method "preMountPrivate" with #[PreMount] attribute must be public.',
+                    24,
+                    'Change the method visibility to public.',
+                ],
             ]
         );
     }