Use dedicated assertInstanceOf assertion

[carusogabriel]

Using this dedicated assertion, we can have better error messages:

-$this->assertTrue($error instanceof \RuntimeException); // Failed asserting that false is true.
+$this->assertInstanceOf(\RuntimeException::class, $error); // Failed asserting that an object is an instance of class "RuntimeException".

[clue]

@carusogabriel Thanks for filing this PR, I can see some use for this 👍

I'm currently undecided because this was actually done on purpose. While the assertInstanceOf() method does indeed provide some better error reporting in case of a test failure (is this a real issue here?), using instanceof aids with static analysis and IDEs, so that it "understands" the methods that are invoked after this check.

Just sharing my thoughts for now, I guess I'm okay with it either way.

[kelunik]

At least PHPStorm also understands assertInstanceOf for static analysis IIRC.

[afk11]

@clue In general, IDE capabilities (which vary greatly from one to the other) shouldn't have a bearing on design decisions. Adding something like this after the assertion would preserve IDE's ability to carry out static analysis.

/** @var \RuntimeException $error */

[clue]

@carusogabriel Thanks for looking into this and for your patience!

Changes LGTM, let's get this in 👍