MatchAssertSameExpectedTypeRector can rewrite a passing assertSame() into a failing one.

Mechanism

The rule picks the expected literal's new type from NodeTypeResolver::getNativeType(), which returns PHPStan's scope-narrowed type at that program point. A narrowed type is sound to report on, but not to rewrite a literal against: it describes the expression where the narrowing was established, while the rewrite lands elsewhere.

Given Criteria::getType(): int|string|null:

$this->assertSame('Any', $criteria->getType());  // phpstan-phpunit narrows getType() to string

$criteria->setTypeId(100);                       // mutates the receiver
$this->assertSame(100, $criteria->getType());    // rewritten to '100' and fails