Why is assert passing all test cases when it shouldn't

Question

public class Main {
    public static void main(String args[]) {
        sumArray(8);
    }

    public static int sumArray(int nums){
       assert nums == 5;
       return nums;
    }
}

I was just wondering, when I pass a number that is not equal to 5, why doesn't the compiler throw any errors, since I am asserting that nums is equal to 5?

Why you expect from compiler to throw the error? Assertions are done runtime. — Gaurav Jeswani, Sep 28 '20 at 04:36
It won't, compiler is meant to check the syntax of your code not the execution. As far as your code syntax is correct you won't get any error. — Gaurav Jeswani, Sep 28 '20 at 04:38
But assert statement is not true, is there any way to show an error. Like this over here — E-SetPrimeEpsilon, Sep 28 '20 at 04:40
https://stackoverflow.com/questions/7865241/assertion-not-working How can i do this on the command line or VSCode — E-SetPrimeEpsilon, Sep 28 '20 at 04:41
Can't you configure JVM arguments in VSC? Anyways, you can run it using `java -ea Main.java` — dan1st, Sep 28 '20 at 04:44
But assert statement is not true, is there any way to show an error. Answer is Yes. You need to understand difference between Compiler and JRE(Java Runtime Environment). So as syntax is correct now you need to run your program in order to find the result of assertions. — Gaurav Jeswani, Sep 28 '20 at 04:49
You would need to enable the assertions as mentioned by @dan1st — Gaurav Jeswani, Sep 28 '20 at 04:56

score 1 · Answer 1 · answered Sep 28 '20 at 05:02

If the program is running with assertions enabled, then the condition is checked at runtime. If the condition is false, the Java runtime system throws an AssertionError.

For backward compatibility, the JVM disables assertion validation by default. They must be explicitly enabled using either the -enableassertions command line argument, or its shorthand -ea

Reference: https://www.baeldung.com/java-assert

Why is assert passing all test cases when it shouldn't

1 Answers1