test: Prove false-positive on protected->private in final class

A final class cannot be extended, therefore `protected` and `private`
are functionally identical. `protected` methods may exist in final
classes for historical reasons, but making them `private` is not a BC
break.

Author: acoulton

test/unit/DetectChanges/BCBreak/ClassBased/MethodRemovedTest.php

@@ -13,6 +13,7 @@
 use Roave\BetterReflection\Reflection\ReflectionClass;
 use Roave\BetterReflection\Reflector\DefaultReflector;
 use Roave\BetterReflection\SourceLocator\Type\SingleFileSourceLocator;
+use Roave\BetterReflection\SourceLocator\Type\StringSourceLocator;
 
 use function array_map;
 use function iterator_to_array;
@@ -60,6 +61,48 @@ public static function classesToBeTested(): array
                     '[BC] REMOVED: Method RoaveTestAsset\ClassWithMethodsBeingRemoved#removedProtectedMethod() was removed',
                 ],
             ],
+            'final class with protected changing to private' => [
+                (new DefaultReflector(new StringSourceLocator(
+                    <<<'PHP'
+                    <?php
+                    final class FinalClassWithProtectedMethod {
+                        protected function foo(string $bar): void {}
+                    }
+                    PHP,
+                    $locator,
+                )))->reflectClass('FinalClassWithProtectedMethod'),
+                (new DefaultReflector(new StringSourceLocator(
+                    <<<'PHP'
+                    <?php
+                    final class FinalClassWithProtectedMethod {
+                        private function foo(string $bar): void {}
+                    }
+                    PHP,
+                    $locator,
+                )))->reflectClass('FinalClassWithProtectedMethod'),
+                [],
+            ],
+            'final class with public changing to private' => [
+                (new DefaultReflector(new StringSourceLocator(
+                    <<<'PHP'
+                    <?php
+                    final class FinalClassWithPublicMethod {
+                        public function foo(string $bar): void {}
+                    }
+                    PHP,
+                    $locator,
+                )))->reflectClass('FinalClassWithPublicMethod'),
+                (new DefaultReflector(new StringSourceLocator(
+                    <<<'PHP'
+                    <?php
+                    final class FinalClassWithPublicMethod {
+                        private function foo(string $bar): void {}
+                    }
+                    PHP,
+                    $locator,
+                )))->reflectClass('FinalClassWithPublicMethod'),
+                ['[BC] REMOVED: Method FinalClassWithPublicMethod#foo() was removed'],
+            ],
         ];
     }
 }