junit eclipse

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JUnit & Eclipse 1

JUnit & Eclipse

DEPARTMENT OF COMPUTER SCIENCE AND SOFTWARE ENGINEERING

CONCORDIA UNIVERSITY

Feb 2, 2009

revision 1.2 Feb 2, 2009

by Emil Vassev & Joey Paquet


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Testing

Software testing is meant to avoid software failure.

A failure is caused by a fault in the code base. A symptom is an observable behavior of the system that enables us to observe

a failure and possibly find its corresponding fault.

The process of discovering what caused a failure is called fault identification.

The process of ensuring that the failure does not happen again is called fault

correction, orfault removal.

Fault identification and fault correction is popularly called debugging.

Software testing, in practice, is about identifying a certain possible system

failure and design a test case that proves that this particular failure is not

experienced by the software.

testing can reveal only the presence of faults, never their absence. [Dijkstra]

:: Definition


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Testing

There are many driving sources for software testing: Requirements-driven testing, Structure-driven testing, Statistics-driven testing,

Risk-driven testing.

There are many levels and kinds of software testing:

Unit Testing, Integration Testing, Function Testing, Acceptance Testing,Installation Testing.

At the day-to-day programming level, unit testing can easily be integrated in

the programming effort by using a Unit Testing Framework.

However, unit testing cannot be applied for higher-level testing purposes such

as function testing or acceptance testing, which are system-level testing

activities.

:: Definition


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Unit Testing

Facilitates change: Unit testing allows the programmer to change or refactor code at a later date,

and make sure the module still works correctly (i.e. regression testing).

Simplifies integration:

Unit testing helps to eliminate uncertainty in the units and can be used in abottom-up integration testing style approach.

Documentation:

Unit testing provides a sort of living documentation of the specifications of the

units of the system. Developers looking to learn what functionality is providedby a unit and how to use it can look at the unit tests to gain understanding of the

units API specifications.

:: Benefits


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Unit Testing

Identifies defects early in the development cycle.

Many small bugs ultimately leads to chaotic system behavior,

which becomes increasingly difficult to work on.

Successful (and meaningful) tests breed confidence.

Makes sure that further changes do not introduce problems into

previously correct code.

Testing forces the programmers to read and analyze their code,

thus removing defects through constant code verification.

:: Benefits (cont.)


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Unit Testing Framework

For a large system, there can be thousands of unit tests, which

can be tedious to maintain and execute.Automated tests support maintainability and extensibility along

with efficiency.

A xUnit Testing Frameworklets a programmer associate Classes

and Methods to corresponding Test Classes and Test Methods.Automation is achieved by automatically setting up a testing

context, calling each test case, verifying their corresponding

expected result, and reporting the status of all tests.

Can be combined with the use of a Software VersioningRepository: prior to any commit being made, unit testing is re-

applied to make sure that the committed code is still working

properly.

:: Rationale


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JUnitthe Javas xUnit Testing Framework

In Java, the standard unit testing framework is known as JUnit.

Test Cases and Test Results are Java objects.

JUnit was created by Erich Gamma and Kent Beck, two authors

best known for Design Patterns and eXtreme Programming,

respectively.

Using JUnit you can easily and incrementally build a test suite

that will help you measure your progress, spot unintended side

effects, and focus your development efforts.

:: Introduction


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JUnitthe Javas Unit Testing Framework

Tested Classthe class that is being tested.

Tested Methodthe method that is tested.

Test Casethe testing of a classs method against some

specified conditions.

Test Case Classa class performing the test cases.Test Case Method a Test Case Classs method

implementing a test case.

Test Suitea collection of test cases that can be tested ina single batch.

:: Key JUnit Notions


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The class TestCase has four important methodsrun(), setUp(), tearDown() and

runTest().

TestCase.run() applies Template Method pattern

public voidrun(){

setUp();

runTest();

tearDown();

}

The Template Method pattern defines the skeleton of an algorithm

in an operation, deferring some steps to subclasses.

All Test Case classes need to be subclasses to the TestCase class.

:: TestCase Class


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JUnit test runners automatically invoke the setUp() method before running

each Test Class. This method typically initializes fields, turns on logging, resets environment

variables, and so forth, i.e. it sets up a context for the test cases to be applied.

protected voidsetUp()

{

System.out.println(" Before testing" );}

In JUnit 4, the initialization method no longer needs to be called setUp().

It just needs to be denoted with the @Before annotation.

We can have multiple methods noted @Before, each running before testing.

@Beforeprotected void ini tiali ze()

{

System.out.println(" Before testing" );

}

:: TestCase Class SetUp


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If we need at the end of each test to do a cleanup operation, we can use

JUnits tearDown()method. For example we can call the garbage collectorthere in case our tests consume large amount of memory.

protected voidtearDown()

{

System.out.println(Af ter testing" );

System.gc();}

In JUnit 4, we can give it a more natural name and annotate it with @After.

@Afterprotected void disposeObjects ()

{

System.out.println(Af ter testing" );

System.gc();

}

:: TestCase Class TearDown


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1. Create the class that you want to test.

2.

Build the test class - with the needed imports and extensions for JUnit. Extend this class from junit.framework.TestCase.

Name all the test methods with a prefix of test.

3. Code the actual test cases.

Validate conditions and invariants using one of the several assert methods.

import juni t.fr amework.* ;public class TestFailureextendsTestCase{

public voidtestSquareRootException() {

try {

SquareRoot.sqrt(-4, 1);fail("Should raise an exception");

}

catch (Exception success) { }

}

}

:: Basics - JUnit 3

Tested Class and Method

Test Case Method

Assertion Statement

Test Case Class


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Tests are identified by an @Test annotation and we no longer need to prefix

our test methods with test. This lets us follow the naming convention that best fits our application.

import juni t.fr amework.* ;

import org.junit.Test;

publi c classTestAdditionextendsTestCase{

private int x = 1;

pri vate int y = 1;

@Testpublic void addition()

{

in t z = x + y;

assertEqual s(2, z);

}

}

:: Basics JUnit 4


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JUnitthe Javas Unit Testing Framework:: Example Tested Class


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JUnitthe Javas Unit Testing Framework:: Example Test Class


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List of different types of assertion statements that you can use to test

your code. These assertions are taken from the JUnit API. assertEquals(expected, actual)

assertEquals(message, expected, actual)

assertEquals(expected, actual, delta)- used on doubles or

floats, where delta is the difference in precision.

assertEquals(message, expected, actual, delta) - used on

doubles or floats, where delta is the difference in precision.

assertFalse(condition)

assertF alse(message, condi tion)

assertNotNull(object)

assertNotNull(message, object)

:: Assertion Statement Reference I
http://www.junit.org/junit/javadoc/3.8.1/index.htmhttp://www.junit.org/junit/javadoc/3.8.1/index.htmhttp://www.junit.org/junit/javadoc/3.8.1/index.htmhttp://www.junit.org/junit/javadoc/3.8.1/index.htm


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assertNotSame(expected, actual)

assertNotSame(message, expected, actual) assertNull(object)

assertNull(message, object)

assertSame(expected, actual)

assertSame(message, expected, actual)

assertTrue(condition)

assertTrue(message, condition)

fail()

fail(message)

failNotEquals(message, expected, actual)

failNotSame(message, expected, actual)

failSame(message)

:: Assertion Statement Reference II

U i T i i E li i JU i


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Unit Testing in Eclipse using JUnit

Eclipse comes with both JUnit and a plug-in for

creating and working with JUnit tests.

Eclipse allows you to quickly create test case classes

and test suite classes to write your test code in.

With Eclipse, Test Driven Development (TDD),becomes very easy to organize and implement.

Eclipse facilitates the testing by generating

automatically stubs for testing class methods.

:: Introduction

U it T ti i E li i JU it


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Once the class we want to test, is created we can start with

building the test cases. To create a test case do [File New JUnit Test Case]

:: Adding a Test Case to the Project

Put the test case class into the same

package as the tested class.



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Unit Testing in Eclipse using JUnit:: Writing Test Cases

This is a test case class for testing SquareRoot

class. The following test case methods test

different aspects of the sqrt()method:

The testSquareRootException() method

demonstrates how to test if an exception is

properly thrown.

The testSquareRootPrecision() method

tests against the precision ofSquareRoot.sqrt().

The testSquareRootAlgorithm() method

tests the square root algorithm.



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Unit Testing in Eclipse using JUnit:: Running the Test

From Menu bar [Run Run As JUnit Test],

or:



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Unit Testing in Eclipse using JUnit:: Test Result Analysis

These two test

case methods

reported failures



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The following test fails because of insufficient precision:

Abs(Math.sqrt(67) - SquareRoot.sqrt(67, 5)) > 0.000001

public voidtestSquareRootPrecision()thr ows Exception

{

Assert.assertEquals(" SquareRoot precision less than 0.000001" ,Math.sqrt(67), SquareRoot.sqrt(67, 5), 0.000001);

}

In order to increase the precision, we increase the number ofiterations from 5 to 6, to arrive at:

Assert.assertEquals(" SquareRoot precision less than 0.000001" ,

Math.sqrt(67), SquareRoot.sqrt(67, 6), 0.000001);



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The following test fails because the SquareRoot.sqrt()method

does notcompute the exact square root of number 67.

public voidtestSquareRootAlgorithm()throws Exception

{

Assert.assertTrue(67 == (SquareRoot.sqrt(67, 6) * SquareRoot.sqrt(67, 6)));}

In order to fix this problem we increase the number of iterations

from 6 to 7, to arrive at:

Assert.assertTr ue(67 == (SquareRoot.sqrt(67, 7) * SquareRoot.sqrt(67, 7)));



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Unit Testing in Eclipse using JUnit:: Rerunning the Test

All the test case

methods passed

the test.



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Unit Testing in Eclipse using JUnit:: Test Suit - Introduction

We have performed tests on only one class, i.e. we have tested

methods under the consideration they belong to the same class.In large projects we have many classes with methods that should

be tested.

For testing multiple classes Eclipse and JUnit expose the concept

ofTest Suit.A Test Suit is a collection of test cases that can be tested in a

single batch.

A Test Suite is a simple way of running one program that, in

turn, runs all test cases.



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Unit Testing in Eclipse using JUnit:: Creating a Test Suit

There are four ways to create a JUnit Test Suite Class. First,

select the directory (usually unittests/) that you wish to create thetest suite class in.

Select [File New Other... Java JUnit JUnit Test

Suite].

Select the arrow of the button in the upper left of thetoolbar. Select [Other... Java JUnit JUnit Test Suite].

Right click on a package in the Package Explorer view in the

Java Perspective, and select [Other... Java JUnit

JUnit Test Suite]. You can create a normal Java class, but import the package

junit.f rameworkand extend the TestSuite class.



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Unit Testing in Eclipse using JUnit:: Adding a New Class to be Tested

This class is taken from the tutorial

paper JUnit Test Infected:

Programmers Love Writing Tests,

by Kent Beck and Erich Gamma



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Unit Testing in Eclipse using JUnit:: Adding a New TestCase Class

This class is taken from the tutorial paper JUnit Test Infected:

Programmers Love Writing Tests,by Kent Beck and Erich Gamma.



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Unit Testing in Eclipse using JUnit:: Creating the Test Suite Class

Creating a Test Suit is straight forward and you just have to

follow the wizard. All the tests would be taken care of by JUnit.



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Unit Testing in Eclipse using JUnit:: Running All Tests

Right click on the test suite class and select [Run As JUnit Test]

Resources


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JUnit

JUnit FAQ

JUnit API

Eclipse

An early look at JUnit 4

Pragmatic Unit Testing in Java with JUnit

http://newton.cs.concordia.ca/~paquet/wiki/index.php/Testing

http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks

Resources
http://www.junit.org/http://junit.sourceforge.net/doc/faq/faq.htmhttp://www.junit.org/junit/javadoc/3.8.1/index.htmhttp://www.eclipse.org/http://www-128.ibm.com/developerworks/java/library/j-junit4.htmlhttp://www.pragmaticprogrammer.com/starter_kit/utj/whatis.pdfhttp://newton.cs.concordia.ca/~paquet/wiki/index.php/Testinghttp://en.wikipedia.org/wiki/List_of_unit_testing_frameworkshttp://en.wikipedia.org/wiki/List_of_unit_testing_frameworkshttp://newton.cs.concordia.ca/~paquet/wiki/index.php/Testinghttp://www.pragmaticprogrammer.com/starter_kit/utj/whatis.pdfhttp://www-128.ibm.com/developerworks/java/library/j-junit4.htmlhttp://www.eclipse.org/http://www.junit.org/junit/javadoc/3.8.1/index.htmhttp://junit.sourceforge.net/doc/faq/faq.htmhttp://www.junit.org/

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