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

Posted by Megan Zanders
Megan Zanders
3,623 Points

I don't understand

I am looking at this question and my mind is going blank. I tried to just take the instantiation and put it in the @Before statement but I guess that wasn't right. What should I do?

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 {
      Calculator 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);
    }
}
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;
    }
}

2 Answers

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

You need to declare calculator as an instance variable first, not as a local variable in setUp():

    private Calculator calculator;

    @Before
    public void setUp() throws Exception {
      calculator = new Calculator();
    }
adrian miranda
adrian miranda
13,561 Points
adrian miranda
adrian miranda
13,561 Points

The way you have declared your calculator, it is local to the setup method. As soon as setup is complete, it ceases to exist. You need to make it available to all methods of this class. How do you normally make a variable available to all methods of a class? By making it a member variable.

You should still initialize it in the Setup method. Just don't declare it there.