Engine doesn't cover branch instanceof String

[SBOne-Kenobi]

Description

Engine generates 1 execution for this method, but doesn't cover throw statement.

public static void charSeqIsNotString(CharSequence cs) {
    if (cs instanceof String) {
        throw new IllegalStateException("CharSequence must be not String!");
    }
}

To Reproduce

Steps to reproduce the behavior:

Steps to reproduce the behavior:

1. Create the mentioned method
2. Make sure that fuzzing turned of (Tools -> UnitTestBot -> Code analysis, toggle must be in the rightest position)
3. Use plugin to generate tests
4. Open the generated test
5. Run tests with coverage

Expected behavior

2 tests are supposed to be generated witch cover all statements.

Actual behavior

1 test generated that don't covers throw statement.

Visual proofs (screenshots, logs, images)

Additional context

This bug is a part of issue #820

[alisevych]

Now one test is generating that covers instanceOf branch.
@CaelmBleidd Can you please advise if symbolic engine should cover the case that condition is false?

[CaelmBleidd]

If the engine covers only one branch where an object is of String type and doesn't cover other subtypes of CharSequence, it is OK (at least, it is known behaviour). It happens because all CharSequence are treated as strings, therefore, the negation of this makes all the branches with it unreachable.

So, we know about this behaviour, it is not what we want in the future, but it is too complicated to fix for now.