Improve test code

[occupant23]

Exchange the expected parameter of the Test annotation with Assert.assertThrows within our test suite.
This reduces the risk of masking an error because the same error was thrown accidentally. Create a PR afterwards.

before:
@Test(expected = UIAssertionError.class

after:

// code before the Throwable is ecpected
Assert.assertThrows(UIAssertionError.class, () -> {
    // code that will produce the Throwable
});