注释类型测试的预期属性未定义

Question

Hi I am trying to test a code that has an exception but when I try to test it it says the attribute expected is undefined for the annotation type test

package Lab1;

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

import junit.framework.Assert;

class MyMathTest {
    MyMath m = new MyMath();
    @Test
    void testDiv() {
        int actual = m.div(6, 2);
        int expected = 3;
        assertEquals(expected, actual);
    }
    /* the error is in the upcoming line*/
    @Test (expected = IllegalArgumentException.class)
    public void testDivException(){
        m.div(5, 0);
    }

}

And here is the error message

the attribute expected is undefined for the annotation type test

Answer 1

You are using JUnit 5 but trying to use JUnit 4's features. Don't mix them.

import org.junit.jupiter.api.Test;

The @Test annotation from JUnit5 don't support what you are trying to use.

To assert exceptions, you need to do

Assertions.assertThrows(IllegalArgumentException.class, () -> m.div(5, 0));

Do not forget to import the package org.junit.jupiter.api.Assertions

More on JUnit 5

Answer 2

You are using a JUnit 4 feature in which what you are doing is correct.

@Test (expected = IllegalArgumentException.class)
public void testDivException(){
    m.div(5, 0);
}

But since after seeing your import, I can tell that you are using JUnit 5 for testing, I would like to tell you that the above method will not work. Since JUnit has its own Assertions class to handle the same. I will show you how.

@Test
public void testDivException() {

    Assertions.assertThrows(IllegalArgumentException.class, new Executable() {

        @Override
        public void execute() throws Throwable {

            m.div(5, 0);

        }
    });
}

The above implementation will work with Java 7 and above. Now if you want to do the same thing using Lambda Expression in Java 8, do this:

@Test
public void testDivException(){
    Assertions.assertThrows(IllegalArgumentException.class, () -> m.div(5, 0));
}

You can read more about Assertion class and JUnit5 here .