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Java Unit Testing in Java How to Test Using Before to not repeat yourself

Saud ALQahtani
Saud ALQahtani
7,842 Points

I've started the shell for the @Before fixture for these tests. See how the Arrange part is duplicated in both tests, ca

I need help i tried everything.. it's not working....

I need a clear answer.

com/example/CalculatorTest.java
package com.example;

import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.*;

public class CalculatorTest {
// declare a Calculator here - don't assign anything to it
    @Before
    public void setUp() throws Exception {
     calculator = new Calculator(); // perfect! 
    }

    @Test
    public void addingMultipleNumbersProducesResult() throws Exception {
        Calculator calculator = new Calculator(); // remove this, you've already done it

        int answer = calculator.addNumbers(1 ,2, 3);

        assertEquals(6, answer);
    }

    @Test
    public void addingSingleNumberTotalsAppropriately() throws Exception {
        Calculator calculator = new Calculator(); // remove this - you've already done it

        int answer = calculator.addNumbers(1);

        assertEquals(1, answer);
    }
}

2 Answers

Hi there,

At the top of the class create a Calculator-sized hole in memory by declaring a Calculator called calculator. Nothing else. Do this before the setUp() method.

Then, initialize it inside the @Before block with calculator = new Calculator();. Then remove the duplicated lines from the tests; just use the calculator within those.

I've added some comments in your code.

Make sense?

Steve.

package com.example;

import org.junit.Before; import org.junit.Test;

import static org.junit.Assert.*;

public class CalculatorTest { private Calculator calculator; @Before public void setUp() throws Exception { calculator = new Calculator(); }

@Test
public void addingMultipleNumbersProducesResult() throws Exception {


    int answer = calculator.addNumbers(1 ,2, 3);

    assertEquals(6, answer);
}

@Test
public void addingSingleNumberTotalsAppropriately() throws Exception {


    int answer = calculator.addNumbers(1);

    assertEquals(1, answer);
}

}