Summary  
This chapter demonstrates how to use various unit-testing assertions—such as assertEquals, assertTrue, assertFalse, assertNotNull, and assertNull—to compare expected versus actual results and make tests pass.  

General domain of usage  
Banking transaction management

It's time to practice with **different Assertions**. A class has been written for you with some methods. Tests for these methods are **already written**, but for some reason, **they keep failing**. Your task is to **find out the reason for this**. The problem lies in the tests, not the code.

Pay close attention to the `expected` and `actual` values. This way, you will understand what **needs to be used** in a specific test case.

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    <li>Your goal is to <b>make the tests work</b>, check the <b>assertions</b> for correctness.</li>
    <li>Some test cases have <b>two assertions at once</b>; pay attention to that.</li>
    <li>You will need to use <b>almost every assertion from the previous chapter</b>, so be attentive.</li>
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public class BankTransactionTest {

    @Test
    public void testInitialBalancePositive() {
        double initialBalance = 100.0;
        BankTransaction bt = new BankTransaction(initialBalance);
        double expected = 100.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testInitialBalanceNegative() {
        double initialBalance = -100.0;
        BankTransaction bt = new BankTransaction(initialBalance);
        double expected = 0.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
        assertNotEquals(initialBalance, actual, 0.001);
    }

    @Test
    public void testDeposit() {
        BankTransaction bt = new BankTransaction(100.0);
        double depositAmount = 50.0;
        boolean depositResult = bt.deposit(depositAmount);
        assertTrue(depositResult);

        double expected = 150.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testDepositNegativeAmount() {
        BankTransaction bt = new BankTransaction(100.0);
        double depositAmount = -50.0;
        boolean depositResult = bt.deposit(depositAmount);
        assertFalse(depositResult);

        double expected = 100.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testWithdrawSuccessful() {
        BankTransaction bt = new BankTransaction(100.0);
        double withdrawalAmount = 50.0;
        boolean withdrawalResult = bt.withdraw(withdrawalAmount);
        assertTrue(withdrawalResult);

        double expected = 50.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testWithdrawInsufficientFunds() {
        BankTransaction bt = new BankTransaction(50.0);
        double withdrawalAmount = 100.0;
        boolean withdrawalResult = bt.withdraw(withdrawalAmount);
        assertFalse(withdrawalResult);

        double expected = 50.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testWithdrawNegativeAmount() {
        BankTransaction bt = new BankTransaction(100.0);
        double withdrawalAmount = -50.0;
        boolean withdrawalResult = bt.withdraw(withdrawalAmount);
        assertFalse(withdrawalResult);

        double expected = 100.0;
        double actual = bt.getBalance();
        assertEquals(expected, actual, 0.001);
    }

    @Test
    public void testNotNullBankTransaction() {
        BankTransaction bt = new BankTransaction(100.0);
        assertNotNull(bt);
    }

    @Test
    public void testNullBankTransaction() {
        BankTransaction bt = null;
        assertNull(bt);
    }
}</textarea>

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Testing is an integral part of software development. Every module of an application should be covered by tests to ensure the correctness of a specific module or the entire application. This course will teach you about the different types of application testing. Additionally, you will practice with unit tests to test individual components of your application.

Let's talk about types of testing and which testing methods developers use. You will learn about the stages an application goes through before being delivered to the client and the specific tests you will need to write.


In this section, we're going to dive into unit testing — you'll get the rundown on its structure in Java and the ins and outs of crafting them the right way. Setting up your IDE, importing necessary libraries, and lots of hands-on practice.


In this section, we will enhance our coding skills by dealing with errors that can also be caught in unit tests. When testing an application, you may come across various errors, and sometimes they should be turned into exceptions. I will explain how to catch exceptions in your code, test them, and handle them properly.

Assertions Practice

Assertions Practice