How to let PHPUnit test property initialization in PHP7.4?

问题

One of the code style changes in our application when adopting PHP7.4 typed properties was to move from:

if (null === $object->value) { ... }

to

if (empty($object->value)) { ... }

Even when a typed property is nullable, the first if-statement will throw an Error.

The next step was on writing tests. Where using empty() on checking whether a typed property is initialized works, the PHPUnit implementation on assertEmpty crashes with the same error.

Obviously assertFalse(isset($obj->value) would work, but what assertion should get used to check if a property was not instantiated? Simplification of the test we would want:

function testInstantiatedAfterCall()
{
    $obj = new Object('http://example.com');
    $obj->changeContainer('Example Container');

    $this->assertNull($obj->value);
    // or
    $this->assertEmpty($obj->value);
}

来源：https://stackoverflow.com/questions/60112627/how-to-let-phpunit-test-property-initialization-in-php7-4