Adds "lowercase" validation rule (#44883)

* Adds "lowercase" validation rule

* Update ValidatesAttributes.php

Co-authored-by: Taylor Otwell <[email protected]>

Author: timacdonald

src/Illuminate/Validation/Concerns/ValidatesAttributes.php

@@ -1158,6 +1158,19 @@ public function validateLte($attribute, $value, $parameters)
         return $this->getSize($attribute, $value) <= $this->getSize($attribute, $comparedToValue);
     }
 
+    /**
+     * Validate that an attribute is lowercase.
+     *
+     * @param  string  $attribute
+     * @param  mixed  $value
+     * @param  array<int, int|string>  $parameters
+     * @return bool
+     */
+    public function validateLowercase($attribute, $value, $parameters)
+    {
+        return Str::lower($value) === $value;
+    }
+
     /**
      * Validate the MIME type of a file is an image MIME type.
      *

tests/Validation/ValidationValidatorTest.php

@@ -1803,6 +1803,33 @@ public function testGreaterThan()
         $this->assertTrue($v->passes());
     }
 
+    public function testLowercase()
+    {
+        $trans = $this->getIlluminateArrayTranslator();
+        $v = new Validator($trans, [
+            'lower' => 'lowercase',
+            'mixed' => 'MixedCase',
+            'upper' => 'UPPERCASE',
+            'lower_multibyte' => 'carácter multibyte',
+            'mixed_multibyte' => 'carÁcter multibyte',
+            'upper_multibyte' => 'CARÁCTER MULTIBYTE',
+        ], [
+            'lower' => 'lowercase',
+            'mixed' => 'lowercase',
+            'upper' => 'lowercase',
+            'lower_multibyte' => 'lowercase',
+            'mixed_multibyte' => 'lowercase',
+            'upper_multibyte' => 'lowercase',
+        ]);
+
+        $this->assertSame([
+            'mixed',
+            'upper',
+            'mixed_multibyte',
+            'upper_multibyte',
+        ], $v->messages()->keys());
+    }
+
     public function testLessThan()
     {
         $trans = $this->getIlluminateArrayTranslator();