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

What am i doing wrong its showing a bummer

Unit testing in Java

com/example/CalculatorTest.java
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 {
        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

Zhaopeng Wang
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Zhaopeng Wang
Full Stack JavaScript Techdegree Graduate 32,208 Points
  • You need to create a private field Calculator calculator
  • Next, remove the duplicate Calculator initialization in the tests
  • The main point of setUp here is to apply DRY principle
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 = this.calculator.addNumbers(1 ,2, 3);

        assertEquals(6, answer);
    }

    @Test
    public void addingSingleNumberTotalsAppropriately() throws Exception {

        int answer = this.calculator.addNumbers(1);

        assertEquals(1, answer);
    }
}

Thank you very much it was helpful