Add failing test for is() method

[adamwathan]

For some reason, retrieving a model from the database isn't setting it's connection name, so if you create a model, retrieve it, and use is() to find out if it's the same model, it fails.

[adamwathan]

So it looks like the primary break happened here, where the connection parameter was removed. It was still being provided in getModels, but not actually getting applied:

1ae29d9

Oddly, I also had to switch $this->model->getConnectionName() to $this->query->getConnection()->getName() to get the right connection name, but that doesn't appear to be reverting any other change; it's always used $this->model->getConnectionName() in the past 🤔

Some other unit tests are broken now due to missing mocked methods, but will look at those next.

[themsaid]

I've opened a PR to fix this issue and included more details about the changes that lead to it: #18769

Here's what I found:

In #17395 we moved the model's create() and forceCreate() methods to the Builder to allow something like User::on('myCustomConnection')->create();, before that creating a model on a different collection was a bit hacky.

After that it was pretty obvious that hydrate() and fromQuery() can be moved to the builder instance as well, since we won't have to pass that $connection argument and we just get it from the Builder instance, that's when 1ae29d9 was committed.

However in that commit we removed the argument but forgot to pass the connection name from the Builder instance, leaving the connection as null when we retrieve a model.

In this PR we simply set the connection using $this->query->getConnection()->getName(), just like we do in create() and forceCreate().

This will solve the failing test in #18760 without having to re-introduce the $connection argument to the hydrate() method.

[pschmidt88]

I'm having the same issue in 5.3