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

Posted by Latoya Brown
Latoya Brown
2,289 Points

can anyone help?

Please help!

I've started the shell for the @Before fixture for these tests. See how Calculator calculator = new Calculator() is duplicated in both tests? Can you help me fix that please?

Use the @Before method to instantiate a new Calculator and use that instance in each method. Don't forget to remove the Calculator instances from each test.

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

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

import static org.junit.Assert.*;

public class CalculatorTest {

    @Before
    public void setUp() throws Exception {

    }

    @Test
    public void addingMultipleNumbersProducesResult() throws Exception {
        Calculator calculator = new Calculator();

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

        assertEquals(6, answer);
    }

    @Test
    public void addingSingleNumberTotalsAppropriately() throws Exception {
        Calculator calculator = new Calculator();

        int answer = calculator.addNumbers(1);

        assertEquals(1, answer);
    }
}
com/example/Calculator.java 
package com.example;

public class Calculator {

    public int addNumbers(int... numbers) {
        int total = 0;
        for (int number : numbers) {
            total += number;
        }
        return total;
    }
}

1 Answer

Jen Dunlap
Jen Dunlap
4,385 Points
Jen Dunlap
Jen Dunlap
4,385 Points

In the @Before public void setUp() throws Exception{}

You need to add Calculator calculator = new Calculator(); between the curly brackets.

Then in each test remove the line for creating a new calculator.

By adding it to the @Before it will create a new calculator for you before each test rather than you manually having to create one.

Latoya Brown
Latoya Brown
2,289 Points

thank you!