Adjusted NullableRule

Will return true only if value is null
Validation message is updated to specify that the attribute has to be nullable

Author: Fa-BRAIK

src/Validation/Rules/NullableRule.php

@@ -12,7 +12,7 @@ class NullableRule implements ValidationRule
 
     public function evaluate(mixed $value): bool
     {
-        return true;
+        return is_null($value);
     }
 
     /** 
@@ -25,6 +25,6 @@ public static function make(?array $parameters = null): self
 
     public function validationMessage(): string
     {
-        return '';
+        return 'The :attribute must be nullable.';
     }
 }

tests/Unit/Validation/Rules/NullableRuleTest.php

@@ -19,7 +19,7 @@ final class NullableRuleTest extends ValidationRuleTestCase
     public function validate_validation_message(): void
     {
         self::assertEquals(
-            '',
+            'The :attribute must be nullable.',
             NullableRule::make()->validationMessage()
         );
     }
@@ -43,12 +43,12 @@ public static function data_provider(): array
                 'valueToBeEvaluated' => null,
                 'expectedResult' => true,
             ],
-            'Will return true if the value exists' => [
+            'Will return false if the value is different then null' => [
                 'validationRuleClassString' => NullableRule::class,
                 'makeParams' => null,
                 'expectedMakeException' => null,
                 'valueToBeEvaluated' => 'Something',
-                'expectedResult' => true,
+                'expectedResult' => false,
             ]
         ];
     }