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Junit 4: The Ultimate Unit Test Framework

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0% found this document useful (0 votes)

92 views46 pages

Junit 4: The Ultimate Unit Test Framework

Uploaded by

Almog Goldberg

We take content rights seriously. If you suspect this is your content, claim it here.

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JUnit 4

The ultimate unit test framework

copyright 2008 trainologic LTD

JUnit 4

• Introduction
• Test Cases and Test Suites
• Parameterized Tests
• Running JUnit Tests

copyright 2008 trainologic LTD

JUnit 4

Introduction to JUnit

• If we had to test our code by hand, it would be

practically impossible to handle Test Driven
Development.

• JUnit is the most popular automated testing framework.

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copyright 2008 trainologic LTD
JUnit 4

Introduction to JUnit

• A simple yet powerful open-source framework to write

Java automated tests.

• It is an instance of the xUnit architecture.

• Licensed by IBM's Common Public License Version 0.5
• Hosted by Sourceforge
• Current version 4.4

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copyright 2008 trainologic LTD
JUnit 4

Introduction to JUnit

• JUnit consists of the following components:

• Runners - Run the tests.

• Fixtures - Initialize common objects.

• Assertions - Test expected results.

5
copyright 2008 trainologic LTD
JUnit 4

Introduction to JUnit

• When we use JUnit we write:

• Tests = Methods.
• Test Case = Class with several tests.
• Test Suite = An aggregation of several test cases
(optional).

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copyright 2008 trainologic LTD
JUnit 4

Installing JUnit

• Download junit.zip.
• Unzip it.
• Add the junit.jar to you classpath.
• And.. Voila... you are good to go.

Usually this is not necessary as most modern IDEs

come with built-in JUnit support.

7
copyright 2008 trainologic LTD
JUnit 4

• Introduction
• Test Cases and Test Suites
• Parameterized Tests
• Running JUnit Tests

copyright 2008 trainologic LTD

JUnit 4

Test

• A simple void method checking a piece of code.

• Tests are marked with the @Test annotation.

@Test
public void testAdd() throws Exception {
double first = 5;
double second = 5;
Calculator calc = new Calculator();
Assert.assertEquals(first + second, calc.add(first, second));
}

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copyright 2008 trainologic LTD
JUnit 4

Test

• Test methods optionally are declared as throwing

Exception.

• In case an Exception is thrown by the test, the test is

marked as “failed”.

• Throwing an Exception is optional and is not the

common way to fail a test. Usually, what fails a test is a
failed assertion.

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copyright 2008 trainologic LTD
JUnit 4

Test

• In case throwing an Exception is the expected behavior,

we can mark the to expect a specific type of Exception.

• This test will fail in case it doesn’t throw

LoginException.

@Test(expected=LoginException.class)
public void testLoginException() throws LoginException {
...
}

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copyright 2008 trainologic LTD
JUnit 4

Test

• The class org.junit.Assert is a collection of static assert

methods.

• These methods help us check the output of the checked

code against the expected value.

• In case the asserted condition is false, the test fails,

and the supplied message is logged.

Assert.assertEquals(message, expected, returnValue);

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copyright 2008 trainologic LTD
JUnit 4

Test
• There is a wide variety of assertions:

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copyright 2008 trainologic LTD
JUnit 4

Test
• Another way to fail the test is by calling the method
fail().

@Test
public void testSomething() throws Exception {
...
switch(i) {
case a:
... break;
case b:
... break;
default:
Assert.fail();
}
}

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copyright 2008 trainologic LTD
JUnit 4

Test
• It is also possible to add a timeout to the test.
• In case the test hasn’t finished befoer timeout, it will
fail.
• Set the timeout attribute of the @Test annotation to
the allowed time in milliseconds.

@Test(timeout=1)
public void testSomething() throws Exception {
...
}

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copyright 2008 trainologic LTD
JUnit 4

Test Cases

• A Test Case is a simple class which includes one or

more test methods:

public class ExampleTestCase {

@Test
public void testAdd() throws Exception {...}

@Test
public void testSubstruct() throws Exception {...}

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copyright 2008 trainologic LTD
JUnit 4

Test Cases
• Sometimes, tests share resources.
Will the following example work?

public class ExampleTestCase {

private ShoppingCart cart;
@Test
public void testAddToCart() throws Exception {
cart.add(...);
...
}
@Test
public void testCheckout() throws Exception {
cart.checkout();
...
}
}

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copyright 2008 trainologic LTD
JUnit 4

Test Cases
• Even though ShoppingCart is a shared resource, we
wouldn’t want both tests to use the same cart.

• This will create coupling between the tests.

• To decouple the tests and avoid code duplication, we
use Fixtures.

18
copyright 2008 trainologic LTD
JUnit 4

Fixtures
• Fixtures are simple methods annotated with @Before
and @After.

• Using fixtures allows us to initialize objects before each

test and clean up after each test.

public class ExampleTestCase {

private ShoppingCart cart;
@Before
public void init() {cart = new ShoppingCart();}
@After
public void destroy() {cart.rollback();}
@Test
public void testAddToCart() throws Exception {...}
@Test
public void testCheckout() throws Exception {...}

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copyright 2008 trainologic LTD
JUnit 4

Fixtures

init() - @Before