some test generated for a method in an (non-static) inner class does not make much sense.
First, the outer class is initalized as null.
Then, the member subJobData is assigned a freshly created object.
However, calling the constructor for an inner class requires, that the outer class is a valid instance.
AFAIK, a (hidden) reference to the outer object is passed to the SubJobData().
The whole construct fails, when the outer object does not exist.
Diffblue should not create tests like that.
This is an older problem, but as you see from the JavaDoc, the DisplayName and the methodName this was generated from a recent Diffblue version.
The yellow background marker from IntelliJ on new SubJobData( new …) indicates ‘inner class construction will produce NullPointerException’.
Thank you for sharing this example behaviour, it’s certainly an interesting example.
I am looking into this with our engineering team.
In the meantime, would it be possible to confirm the version of Cover used when you encountered this? - at the moment I am assuming 2024.1201 or 2024.12.02
It sounds like you’re looking for a test related to inner classes in programming, particularly in object-oriented languages like Java. Below is an example of a “weird” or challenging test that could involve inner classes:
Inner Class Test - Weird Challenge
Question 1: Nested Inner Class and Access Modifiers
Consider the following code snippet:
java
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class Outer {
private int outerVar = 10;
class Inner {
private int innerVar = 20;
void printVars() {
System.out.println("Outer Variable: " + outerVar);
System.out.println("Inner Variable: " + innerVar);
}
}
}
What will happen if we try to access outerVar directly from the main method outside the Outer class, assuming the following code in main:
java
Copy
public class Test {
public static void main(String[] args) {
Outer outer = new Outer();
System.out.println(outer.outerVar); // Will this compile?
}
}
A) It will compile because outerVar is an instance variable.
B) It will not compile because outerVar is private.
C) It will compile and print the value 10.
D) It will compile but throw a runtime error.
Question 2: Static Inner Class Confusion
You have the following code:
java
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class Outer {
static int outerStaticVar = 50;
static class StaticInner {
void display() {
System.out.println(outerStaticVar);
}
}
}
What happens when you attempt to compile and run the following:
java
Copy
public class Test {
public static void main(String[] args) {
Outer.StaticInner inner = new Outer.StaticInner();
inner.display(); // Will this work?
}
}
A) Yes, it will work because StaticInner is a static class.
B) No, it will throw an error because StaticInner needs an instance of Outer.
C) It will compile but not print anything.
D) It will compile and print null.
Question 3: Inner Class and Memory Leaks
Which of the following statements is true regarding an inner class in Java?
A) An inner class can prevent the garbage collection of its outer class if a reference to the inner class is retained.
B) Inner classes always have references to the outer class, preventing the outer class from being garbage collected.
C) Static inner classes do not retain references to the outer class.
D) All of the above.
You are asked to implement a simple interface using an anonymous inner class:
java
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interface MyInterface {
void doSomething();
}
public class Test {
public static void main(String[] args) {
MyInterface obj = new MyInterface() {
public void doSomething() {
System.out.println("Anonymous Inner Class");
}
};
}
}
What will happen if you try to call the method obj.doSomething(); inside main?
A) It will compile and print Anonymous Inner Class.
B) It will compile but throw a NullPointerException at runtime.
C) It will not compile because you cannot instantiate an interface.
D) It will compile but the program will not do anything. It sounds like you’re looking for a test related to inner classes in programming, particularly in object-oriented languages like Java. Below is an example of a “weird” or challenging test that could involve inner classes:
Inner Class Test - Weird Challenge
Question 1: Nested Inner Class and Access Modifiers**
Consider the following code snippet:
java
Copy
class Outer {
private int outerVar = 10;
class Inner {
private int innerVar = 20;
void printVars() {
System.out.println("Outer Variable: " + outerVar);
System.out.println("Inner Variable: " + innerVar);
}
}
}
What will happen if we try to access outerVar directly from the main method outside the Outer class, assuming the following code in main:
java
Copy
public class Test {
public static void main(String[] args) {
Outer outer = new Outer();
System.out.println(outer.outerVar); // Will this compile?
}
}
A) It will compile because outerVar is an instance variable.
B) It will not compile because outerVar is private.
C) It will compile and print the value 10.
D) It will compile but throw a runtime error.
Question 2: Static Inner Class Confusion
You have the following code:
java
Copy
class Outer {
static int outerStaticVar = 50;
static class StaticInner {
void display() {
System.out.println(outerStaticVar);
}
}
}
What happens when you attempt to compile and run the following:**
java
Copy
public class Test {
public static void main(String[] args) {
Outer.StaticInner inner = new Outer.StaticInner();
inner.display(); // Will this work?
}
}
A) Yes, it will work because StaticInner is a static class.
B) No, it will throw an error because StaticInner needs an instance of Outer.
C) It will compile but not print anything.
D) It will compile and print null.
Question 3: Inner Class and Memory Leaks
Which of the following statements is true regarding an inner class in Java?
A) An inner class can prevent the garbage collection of its outer class if a reference to the inner class is retained.
B) Inner classes always have references to the outer class, preventing the outer class from being garbage collected.
C) Static inner classes do not retain references to the outer class.
You are asked to implement a simple interface using an anonymous inner class:
java
Copy
interface MyInterface {
void doSomething();
}
public class Test {
public static void main(String[] args) {
MyInterface obj = new MyInterface() {
public void doSomething() {
System.out.println("Anonymous Inner Class");
}
};
}
}
What will happen if you try to call the method obj.doSomething(); inside main?
A) It will compile and print Anonymous Inner Class.
B) It will compile but throw a NullPointerException at runtime.
C) It will not compile because you cannot instantiate an interface.
D) It will compile but the program will not do anything.
