Make AssertSameNullExpectedRule auto-fixable

src/Rules/PHPUnit/AssertSameNullExpectedRule.php

@@ -47,11 +47,32 @@ public function processNode(Node $node, Scope $scope): array
 
 		if ($expectedArgumentValue->name->toLowerString() === 'null') {
 			return [
-				RuleErrorBuilder::message('You should use assertNull() instead of assertSame(null, $actual).')->identifier('phpunit.assertNull')->build(),
+				RuleErrorBuilder::message('You should use assertNull() instead of assertSame(null, $actual).')
+					->identifier('phpunit.assertNull')
+					->fixNode($node, static function (CallLike $node) {
+						$node->name = new Node\Identifier('assertNull');
+						$node->args = self::rewriteArgs($node->args);
+
+						return $node;
+					})
+					->build(),
 			];
 		}
 
 		return [];
 	}
 
+	/**
+	 * @param array<Node\Arg|Node\VariadicPlaceholder> $args
+	 * @return list<Node\Arg|Node\VariadicPlaceholder>
+	 */
+	private static function rewriteArgs(array $args): array
+	{
+		$newArgs = [];
+		for ($i = 1; $i < count($args); $i++) {
+			$newArgs[] = $args[$i];
+		}
+		return $newArgs;
+	}
+
 }

tests/Rules/PHPUnit/AssertSameNullExpectedRuleTest.php

@@ -34,6 +34,11 @@ public function testRule(): void
 		]);
 	}
 
+	public function testFix(): void
+	{
+		$this->fix(__DIR__ . '/data/assert-same-null-expected-fixable.php', __DIR__ . '/data/assert-same-null-expected-fixable.php.fixed');
+	}
+
 	/**
 	 * @return string[]
 	 */

tests/Rules/PHPUnit/data/assert-same-null-expected-fixable.php

@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace AssertSameNullTestCaseFix;
+
+class AssertSameNullExpectedTestCase extends \PHPUnit\Framework\TestCase
+{
+	/**
+	 * @return null
+	 */
+	public function returnNull()
+	{
+		return null;
+	}
+
+	public function doFoo(): void
+	{
+		$this->assertSame(null, 'a');
+
+		\PHPUnit\Framework\Assert::assertSame($this->returnNull(), 'foo');
+	}
+
+}

tests/Rules/PHPUnit/data/assert-same-null-expected-fixable.php.fixed

@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace AssertSameNullTestCaseFix;
+
+class AssertSameNullExpectedTestCase extends \PHPUnit\Framework\TestCase
+{
+	/**
+	 * @return null
+	 */
+	public function returnNull()
+	{
+		return null;
+	}
+
+	public function doFoo(): void
+	{
+		$this->assertNull('a');
+
+		\PHPUnit\Framework\Assert::assertSame($this->returnNull(), 'foo');
+	}
+
+}