Suppress getimagesize() warnings (#17944)

* Suppress getimagesize() warnings

`getimagesize` will fail with a notice on files smaller than 12 bytes.
This ends up becoming an ErrorException which is pretty annoying.

Suppressing the warning is enough to still end up with a `false` result
which will fail the validation gracefully instead of grueing up your
stew.

* Add test to prove need for warning suppression

src/Illuminate/Validation/Concerns/ValidatesAttributes.php

@@ -424,7 +424,7 @@ protected function validateDigitsBetween($attribute, $value, $parameters)
      */
     protected function validateDimensions($attribute, $value, $parameters)
     {
-        if (! $this->isValidFileInstance($value) || ! $sizeDetails = getimagesize($value->getRealPath())) {
+        if (! $this->isValidFileInstance($value) || ! $sizeDetails = @getimagesize($value->getRealPath())) {
             return false;
         }
 

tests/Validation/ValidationValidatorTest.php

@@ -1923,6 +1923,13 @@ public function testValidateImageDimensions()
 
         $v = new Validator($trans, ['x' => $uploadedFile], ['x' => 'dimensions:ratio=1']);
         $this->assertTrue($v->fails());
+
+        // This test fails without suppressing warnings on getimagesize() due to a read error.
+        $emptyUploadedFile = new \Symfony\Component\HttpFoundation\File\UploadedFile(__DIR__.'/fixtures/empty.gif', '', null, null, null, true);
+        $trans = $this->getIlluminateArrayTranslator();
+
+        $v = new Validator($trans, ['x' => $emptyUploadedFile], ['x' => 'dimensions:min_width=1']);
+        $this->assertTrue($v->fails());
     }
 
     /**