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

Akash Sharma
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.a{fill-rule:evenodd;}techdegree
Akash Sharma
Full Stack JavaScript Techdegree Student 14,147 Points
Posted by Akash Sharma
.a{fill-rule:evenodd;}techdegree
Akash Sharma
Full Stack JavaScript Techdegree Student 14,147 Points

How is this answer different from the video before?

public class CalculatorTest {

private Calculator calculator;

@Before
public void setUp() throws Exception {
    calculator = new Calculator();

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

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



import static org.junit.Assert.*;

public class CalculatorTest {

  public Calculator calculator;

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

    @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;
    }
}

2 Answers

Kourosh Raeen
Kourosh Raeen
23,733 Points
Kourosh Raeen
Kourosh Raeen
23,733 Points

You should initialize the calculator object just once in the setUp() method.

Hannah Flynn
Hannah Flynn
21,429 Points

Can you show me that in code mode?

Kourosh Raeen
Kourosh Raeen
23,733 Points
Kourosh Raeen
Kourosh Raeen
23,733 Points

Sure. Here's how it would look like:

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);
    }
}
Hannah Flynn
Hannah Flynn
21,429 Points
Hannah Flynn
Hannah Flynn
21,429 Points

Thanks! It worked.