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

praveen gudimetla
praveen gudimetla
464 Points

CalculatorTest JUnit issues

Hi,

I tried my test class as below. I get error Bummer! please only intitialze Calculator once in Before Gags. how to fix this error. please advuse

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 = 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/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 = 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;
    }
}

5 Answers

You actually did it correctly but tests can be finicky.

Delete the commented code (//Calculator calculator = new Calculator();) and you will be on to the next one!!

praveen gudimetla
praveen gudimetla
464 Points

package com.example;

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

import static org.junit.Assert.*; Calculator calculator; public class CalculatorTest {

@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);
}

}

i removed commented lines as above getting compilation errors like

./com/example/CalculatorTest.java:7: error: class, interface, or enum expected Calculator calculator; ^ ./com/example/CalculatorTest.java:13: error: cannot find symbol calculator=new Calculator(); ^ symbol: variable calculator location: class CalculatorTest ./com/example/CalculatorTest.java:21: error: cannot find symbol int answer = calculator.addNumbers(1 ,2, 3); ^ symbol: variable calculator location: class CalculatorTest ./com/example/CalculatorTest.java:30: error: cannot find symbol int answer = calculator.addNumbers(1); ^ symbol: variable calculator location: class CalculatorTest 4 errors

please advise

praveen gudimetla
praveen gudimetla
464 Points

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);
}

}

above gives below error Bummer! There is a compiler error. Please click on preview to view your syntax errors!

You just need to declare it in the global scope and instantiate it in the @Before. Then delete the other 2 declarations and you're golden.

This code passes.

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);
    }
}