Errors in test generation when there is variable hiding in src code

[volivan239]

Description

When we generate tests for a class with a field that hides field from superclass, incorrect tests are generated.

To Reproduce

Launch the plugin on class C in the following example:

class A {
    public int f;
    void setF(int val) { this.f = val; }
    int getF() { return this.f; }
}

class B extends A {
    public int f;
}

public class C {
    boolean foo(B b) {
        return b.getF() == b.f + 1;
    }
    boolean bar(B b) {     // replace body with return b.getF() == b.f and test generation will work ok
        if (b.getF() == b.f)  
            return true;
        else
            return false;
    }
}

Expected behavior

Correct tests with complete coverage are generated.

Actual behavior

For function bar plugin generates incorrect test testBar_BGetFEqualsBF (assertEquals in this test fails when launching).
For function foo there is no testcase in which return value would be true.

Both problems disappear if we rename field in class A to any other name.

Visual proofs (screenshots, logs, images)

Incorrect test generated:

    @Test
    @DisplayName("bar: BGetF -> return true")
    public void testBar_BGetFEqualsBF() {
        C c = new C();
        B b = new B();
        b.f = 1;

        boolean actual = c.bar(b);

        assertFalse(actual);

        int finalBF = b.f;

        assertEquals(0, finalBF);
    }

Environment

plugin, Java11

Additional context

The problem also happens if we mark the field in class B as private: in some of the generated tests there will be accesses to this private member, so generated tests are not even compilable. Try launching test generation on C.baz() in this example:

package inheritanceIssues;

class A {
    public int f;
    void setF(int val) { this.f = val; }
    int getF() { return this.f; }
}

class B extends A {
    private int f;
}

public class C {
    boolean baz(B b) {
        return b.getF() == 1;
    }
}

[volivan239]

The issue is related to engine and codegen. Engine part of the issue should be resolved in #627. Codegen part is WIP, see comment for more details.

[volivan239]

The issue is now split to engine part (#647) and codegen part (#646). It will be closed after solving both.

[volivan239]

Fixed by #627 and #763