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Start your free trialGary Mclean
5,756 Pointsuse @Before to instantiate a object in JUnit
hi,
the question seems to be easy enough but cant seem to see what i am doing wrong here, it asks me to instantiate a new object and i do that however, it doesnt seem to work.
Any help would be awesome!
P.s the question is I've started the shell for the @Before fixture for these tests. See how the Arrange part is duplicated in both tests, can you help me fix that please?
Use the @Before method to instantiate a new Calculator and use that instance in each method.
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 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);
}
}
package com.example;
public class Calculator {
public int addNumbers(int... numbers) {
int total = 0;
for (int number : numbers) {
total += number;
}
return total;
}
}
4 Answers
Miguel Canas
Python Development Techdegree Student 11,470 PointsHi Gary,
You're super close. Here's a hint: consider the scope of the calculator variable in this method:
@Before
public void setUp() throws Exception {
Calculator calculator = new Calculator();
}
Based on what you've written here, will calculator
be accessible outside of the setUp() method? What can you do to make calculator
available to other methods in this class?
Hope that helps!
~ Miguel
Bala Selvam
Python Development Techdegree Student 30,590 PointsI still don't get it, it is still giving me an error
Austin Gladfelter
1,801 PointsI'm getting the same thing. Did you ever manage to resolve this?
Christian Dolan
1,455 PointsHi im having the same issue as you gary, my tests both fail. How did you end up resolving that?
Christian Dolan
1,455 PointsNevermind I figured it out. I had Calculator calculator = new Calculator();
When it needed to just be calculator = new Calculator();
David Kaiser
2,079 PointsSo my code is below.
It throws the error "Bummer! Please only initialize the Calculator object once in the setUp method that is annotated with @Before."
package com.example;
import org.junit.Before;
import org.junit.Test;
import static org.junit.Assert.*;
public class CalculatorTest {
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);
}
}
so I only declared the variable once, inside the Setup method, as in the code below, and got this error: There is a compiler error. Please click on preview to view your syntax errors!
A check of the preview shows this:
./com/example/CalculatorTest.java:19: error: cannot find symbol
int answer = calculator.addNumbers(1 ,2, 3);
^
symbol: variable calculator
location: class CalculatorTest
./com/example/CalculatorTest.java:28: error: cannot find symbol
int answer = calculator.addNumbers(1);
^
symbol: variable calculator
location: class CalculatorTest
2 errors
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 {
//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);
}
}
Gary Mclean
5,756 PointsGary Mclean
5,756 PointsHi, thanks for the tip i made a private field however, it makes the tests fail. any idea why?
" Bummer! 2 out of 2 tests failed. See preview for more details."
"2 FAILURES
addingSingleNumberTotalsAppropriately: null addingMultipleNumbersProducesResult: null
"
Miguel Canas
Python Development Techdegree Student 11,470 PointsMiguel Canas
Python Development Techdegree Student 11,470 Pointscan you post your updated test class again?
Gary Mclean
5,756 PointsGary Mclean
5,756 PointsUpdated, cheers
Miguel Canas
Python Development Techdegree Student 11,470 PointsMiguel Canas
Python Development Techdegree Student 11,470 PointsOK
On this line
Calculator calculator = new Calculator()
you're declaring the variable in the method's local scope by preceding it with the class name, and not assigning it to the private field.Gary Mclean
5,756 PointsGary Mclean
5,756 PointsAh, ok, that fixed it. Thanks