IntVal: Validate negative numbers properly

library/Rules/IntVal.php

@@ -13,8 +13,9 @@ declare(strict_types=1);
 
 namespace Respect\Validation\Rules;
 
-use function ctype_digit;
 use function is_int;
+use function is_string;
+use function preg_match;
 
 /**
  * Validates if the input is an integer.
@@ -36,6 +37,10 @@ final class IntVal extends AbstractRule
             return true;
         }
 
-        return ctype_digit($input);
+        if (!is_string($input)) {
+            return false;
+        }
+
+        return preg_match('/^-?\d+$/', $input) === 1;
     }
 }

tests/integration/rules/intVal.phpt

@@ -35,9 +35,23 @@ try {
 } catch (NestedValidationException $exception) {
     echo $exception->getFullMessage() . PHP_EOL;
 }
+
+try {
+    v::not(v::intVal())->assert(-42);
+} catch (NestedValidationException $exception) {
+    echo $exception->getFullMessage() . PHP_EOL;
+}
+
+try {
+    v::not(v::intVal())->assert('-42');
+} catch (NestedValidationException $exception) {
+    echo $exception->getFullMessage() . PHP_EOL;
+}
 ?>
 --EXPECT--
 "42.33" must be an integer number
 2 must not be an integer number
 - "Foo" must be an integer number
 - 3 must not be an integer number
+- -42 must not be an integer number
+- "-42" must not be an integer number

tests/unit/Rules/IntValTest.php

@@ -49,6 +49,9 @@ final class IntValTest extends RuleTestCase
             [$rule, 0b101010],
             [$rule, 0x2a],
             [$rule, '089'],
+            [$rule, -42],
+            [$rule, '-42'],
+            [$rule, '-042'],
         ];
     }