Junit Testing Tips - Constructor Is Called Earlier Executing Exam Methods

Even though around all Java programmers either role JUnit or TestNG for in that place unit of measurement testing need along amongst to a greater extent than or less mock object generation libraries e.g. Mockito, but non everyone spends fourth dimension as well as endeavour to acquire subtle details of these testing libraries, at to the lowest degree non inwards proportion of whatever pop framework like vending car implementation equally a coding exercise. If you lot facial expression at closely, I bring initialized vending car inwards the shape body, which is executed equally business office of the constructor.

I was assuming 1 instance of the vending car is shared betwixt all bear witness methods, equally I was non using @Before as well as @After, JUnit iv annotation for setup() as well as tearDown().

In the outset test, 1 item from Inventory is consumed as well as inwards minute bear witness to a greater extent than or less other item, but when you lot assert count of items based upon the previous test, it volition fail, because you lot are testing a dissimilar vending car instance, which has dissimilar inventory.

So always, recollect that JUnit calls the constructor of bear witness shape earlier executing the bear witness method. You tin verify it past times putting a System.out.println message inwards the constructor itself. Btw, if you lot are simply starting amongst JUnit or bring used it quite a long ago, as well as thus I propose you lot to outset refresh your concepts past times going through JUnit as well as Mockito Crash Course. 

JUnit has already come upward a long means amongst enhancements inwards JUnit 4.0 as well as JUnit 5.0, the latest loose of JUnit.

Code Written inwards Constructor is Executed earlier each Test Method

a constructor.

In the output section, you lot tin meet that message from constructor has appeared ii times, 1 for each bear witness case. This proves that the constructor of JUnit bear witness class is executed earlier each bear witness method.

import java.util.List;

import org.junit.Test;

import static org.junit.Assert.;

/**

  *

  * @author Javin

  */

public class VendingMachineTest {

    private VendingMachine car = new VendingMachine();

  

    public VendingMachineTest(){

        System.out.println("JUnit Framework calls Constructor of bear witness shape earlier executing bear witness methods");

    }

    @Test

    public void buyDrinkWithExactAmount(){

        int cost = machine.choose(Item.COKE);

        assertEquals(70, price);

        assertEquals(Item.COKE, machine.currentItem);

      

        machine.insert(Coin.QUARTER);

        machine.insert(Coin.QUARTER);

        machine.insert(Coin.DIME);

        machine.insert(Coin.DIME);

        assertEquals(70, machine.balance);

        assertEquals(7, (int) machine.coinInvertory.getCount(Coin.DIME));

        assertEquals(7, (int) machine.coinInvertory.getCount(Coin.QUARTER));

      

        Item i = machine.dispense();

        assertEquals(Item.COKE, i);

        assertEquals(4, (int) machine.itemInvertory.getCount(i));

      

        List alter = machine.getChange();

        assertTrue(change.isEmpty());

      

      

    }

  

    @Test

    public void buyDrinkWithMoreAmount(){

        int cost = machine.choose(Item.SPRITE);

        assertEquals(90, price);

        assertEquals(Item.SPRITE, machine.currentItem);

      

        machine.insert(Coin.QUARTER);

        machine.insert(Coin.QUARTER);

        machine.insert(Coin.QUARTER);

        machine.insert(Coin.QUARTER);

      

        assertEquals(100, machine.balance);

        assertEquals(9, (int) machine.coinInvertory.getCount(Coin.QUARTER));

      

        Item i = machine.dispense();

        assertEquals(Item.SPRITE, i);

        assertEquals(4, machine.itemInvertory.getCount(i));

        //this was failing, because past times default VM initialize inventory amongst v items

        assertEquals(4, machine.itemInvertory.getCount(Item.COKE));

      

        List alter = machine.getChange();

        assertEquals(1, change.size());

        assertEquals(Coin.DIME, change.get(0));

        assertEquals(4, machine.coinInvertory.getCount(Coin.DIME));

             

    }

Output:

Testsuite: test.VendingMachineTest

JUnit Framework calls Constructor of bear witness class before executing bear witness methods

JUnit Framework calls Constructor of bear witness class before executing bear witness methods

Tests run: 2, Failures: 1, Errors: 0, Time elapsed: 1.421 sec

Result

------------- ---------------- ---------------

Testcase: buyDrinkWithMoreAmount(test.VendingMachineTest):      FAILED

expected:<4> but was:<5>

junit.framework.AssertionFailedError: expected:<4> but was:<5>

        at test.VendingMachineTest.buyDrinkWithMoreAmount(VendingMachineTest.java:63)

That's all guys. I experience this is a worth knowing item if you lot are using JUnit for writing unit of measurement bear witness inwards your Java project. Sometimes, nosotros bring a põrnikas inwards unit of measurement bear witness itself, but nosotros suspect our code. So it must for all Java developers to know the nitty-gritty of JUnit testing framework equally well.

Further Learning
Unit Testing In Java With JUnit
JUnit as well as Mockito Crash Course
Learn Unit Testing amongst JUnit & Mockito inwards thirty Steps

Thanks for reading this article thus far. If you lot similar this JUnit tips as well as thus delight percentage amongst your friends as well as colleagues. If you lot bring whatever questions or feedback as well as thus delight drib a note.

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