тестирование с JUnit

[zhenya.ya]

Откуда вот такая ошибка??:
.E
Time: 0
There was 1 error:
1) testAge(TestClass) at Main.main(Main.java:7)

FAILURES!!!
Tests run: 1, Failures: 0, Errors: 1

Дано:

cat.java

class Cat{
    private int age;
 
     Cat(int age) {
        this.age = age;
    }
    public int getAge() {
        return age;
    }
}

TestClass.java

class TestClass extends TestCase{
TestClass(String str){
    super(str);
}
    public void testAge(){
        Cat obj1 = new Cat(8);
          assertTrue(obj1.getAge()==8);
    }
}

Main.java

class Main{
    public static void main(String[] args){
        new TestRunner().doRun(new TestClass("testAge"));
    }
}