fix(symony): ensure the kernel is booted before using KernelBrowser::loginUser()

[ttskch]

Q	A
Branch?	4.2
Tickets	Related to #6976 and #7007
License	MIT
Doc PR	N/A

As of #6976 and #7007, calling createClient() no longer boots the kernel when $alwaysBootKernel = false is set, as recommended.

If we use Client::loginUser() when the kernel has not been booted, no error will occur and we will simply remain in a non-logged in state.

So, this PR ensure that the kernel is booted before using KernelBrowser::loginUser(), and that Client::loginUser() always succeeds.

[soyuka]

thanks!

[Crovitche-1623]

Are you sure the static::$booted variable from KernelTestCase variable will not be in sync anymore if the kernel is booted in these methods ? @ttskch
cc @soyuka

[Crovitche-1623]

Don't you think the database may be recreated twice if something like that is used :

// A test using `ApiTestCase`

$client = Client::loginUser();

$anotherClient = static::createClient();

[Crovitche-1623]

NVM, a logged in user could be created without having to create the database. As far as I saw, the only the bootKernel is listened by Alice.

[Crovitche-1623]

Even if the database is created only once, remember that the kernel may be shut down and recreated—for example, when calling static::createClient—so the $booted flag can get out of sync. I’m not sure whether that will cause issues down the line, but it’s worth keeping in mind.