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

Enyang Mercy
PLUS
Enyang Mercy
Courses Plus Student 2,339 Points

Unit Test in java Calculator Test @BeforeMethod

How do i fix the arrange part? I already instantiated a new Calculator in each method. But i can't compile . Can u please identify the error and make corrections. Thanks

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 = 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

You have a couple of problems:

  1. In your before method, you declared an object of type Calculator but you did not assign it a variable name.
  2. The point of having the Calculator in the before method is to avoid repetition in your tests, so you can remove those repeated assignments/instantiations as you are meant to initialise the calculator only once.
  3. Once you remove it from your test methods, you need a way to access it, so you should move calculator to a field/property of the class and leave the instantiation in your before method so that it will be available to all tests.