Data-Driven Unit Testing for Java

Advanced Unit Testing for Java By Denilson Nastacio Data-Driven Unit Testing

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Denilson Nastacio

14 years in software development

Quality Enthusiast

Rational Unified Process practitioner

RTP Scrolls ( http://rtpscrolls.blogspot.com )

SourcePatch ( http://sourcepatch.blogspot.com )

LinkedIn ( http://www.linkedin.com/in/nastacio )

Introduction

Example

Your guessed right, a bank account :-)

Conventional unit testing

Adequate…sometimes

When coverage is not everything

Multiple combinations of input values

Multiple internal states

Complex behavior

The Contenders

JUnit 3.8

JUnit 4.x

TestNG

DDTUnit

Checking Account

public class Account {

private float balance;

private float lineOfCredit;

public Account( float balance, float lineOfCredit) {

super ();

this .balance = balance;

this .lineOfCredit = lineOfCredit;

}

public void deposit( float value) {

if (value < = 0) {

throw new IllegalArgumentException( “ Deposit value (“ + value + “) is not grater than 0 " );

}

balance += value;

}

public float getBalance() {

return balance;

}

Junit 3.8

public void test Valid Deposit() {

Account acc = new Account(0f , 0f);

acc.deposit(50f);

assertEquals (50f, acc.getBalance(), 0f);

}

public void test Zero Deposit() {

try {

acc.deposit(0f);

fail( "Deposit should fail" );

} catch (IllegalArgumentException e) {

// expected

}

}

public void test Negative Deposit() {

try {

acc.deposit(-50f);

// expected

}

}

JUnit 3.8 – Pros and Cons

Pros

Short learning curve

Trivial to write

Cons

Tedious to write

Long files

Input data mixed with source code: difficult to glean all input combinations

JUnit 4.x – Using parameterized tests

@RunWith (Parameterized. class )

public class AccountTest extends TestCase {

private float lineOfCredit;

private float deposit;

private Object result;

@Parameters

public static Collection data() {

return Arrays. asList ( new Object[][] {

{ 0f, 50f, 50f },

{ 0f, 0f, new IllegalArgumentException() },

{ 0f, -5 0f, new IllegalArgumentException() } });

}

public AccountTest( float lineOfCredit, float deposit,

Object result) {

this .lineOfCredit = lineOfCredit;

this .deposit = deposit;

this .result = result;

}

@Test

public void deposit() {

Account acc = new Account(0.0f, lineOfCredit);

boolean expectError = false ;

if (result instanceof IllegalArgumentException) {

expectError = true ;

}

try {

acc.deposit(deposit);

if (expectError) {

} else {

assertEquals(acc.getBalance(),

((Float) result).floatValue(), 0f);

}

if (!expectError) {

throw e;

}

}

}

JUnit 4.x – Pros and Cons

Pros

Built-in separation of data and logic

Good integration with Eclipse

Cons

One class per collection of input parameters

Difficult to handle collections of input parameters for verification of successful runs versus exception handling.

No labels for parameter sets

TestNG

<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">

<suite name="banking-test">

<test name="testValidDeposit">

<parameter name="lineOfCredit" value="0f"/>

<parameter name="deposit" value="50f"/>

<parameter name="result" value="50f"/>

<classes>

<class name=" com.ibm.qse.banking.AccountTestNgTest ">

<methods>

<include name=" testDeposit "/>

</methods>

</class>

</classes>

</test>

<test name="testZeroDeposit">

<parameter name="deposit" value="0f"/>

<parameter name="result" value="IllegalArgumentException"/>

<classes>

...

</class>

</classes>

</test>

<test name="testNegativeDeposit">

<parameter name="deposit" value="-50f"/>

<parameter name="result" value="IllegalArgumentException"/>

<classes>

...

</class>

</classes>

</test>

</suite>

Selected methods must be specified in each “test”element

TestNG – Parameterized tests – Java source

public class AccountTestNgTest {

@Test

@Parameters( { "lineOfCredit", "deposit", "result" })

public void testDeposit( float lineOfCredit, float deposit, String result) {

Account acc = new Account(0f, lineOfCredit);

float expectedBalance = 0f;

try {

expectedBalance = Float. parseFloat (result);

assertEquals (expectedBalance, acc.getBalance());

} catch (NumberFormatException e) {

try {

fail ( "Deposit should fail" );

} catch (IllegalArgumentException e1) {

// expected

}

}

}

TestNG does not support complex Java objects

TestNG – Pros & Cons

Pros

Complete separation of data and logic; separate files

Allows named parameter sets

Good support for grouping tests

Good integration with Eclipse

Cons

No support for complex Java types in the testng.xml file (that is a big one)

Tests in the xml file grouped by parameters instead of class-methods, must map each input sets to a method every time

JUnit competitor (increased learning curve)

Additional Eclipse plug-in required

DDTUnit – XML file (DDT-AccountTest.xml)

<?xml version="1.0" encoding="ISO-8859-1"?>

<ddtunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:noNamespaceSchemaLocation="ddtunit.xsd">

<cluster id=" AccountTest ">

<group id=" testDeposit ">

<test id="valid">

<objs>

<obj id= "lineOfCredit" type="float">50</obj>

<obj id= "deposit" type="float">50</obj>

</objs>

<asserts>

<assert id= "balance" type="float" action="isEqual">50.0f</assert>

</asserts>

</test>

<test id="zero">

<objs>

<obj id="lineOfCredit" type="float">50</obj>

<obj id="deposit" type="float">0</obj>

</objs>

<asserts>

<exception id="expectedException" type="java.lang.IllegalArgumentException"

action="isSimilar">0</exception>

</asserts>

</test>

<test id="negative">

<objs>

<obj id="lineOfCredit" type="float">50</obj>

<obj id="deposit" type="float">-50</obj>

</objs>

<asserts>

<exception id="expectedException“ type="java.lang.IllegalArgumentException"

action="isSimilar">-50</exception>

</asserts>

</test>

</group>

</cluster>

</ddtunit>

Class name Method name

DDTUnit – Java source

public class AccountDDTUnitTest extends DDTTestCase {

public void testDeposit() {

float lineOfCredit = ((Float)getObject( "lineOfCredit" )).floatValue();

float deposit = ((Float)getObject( "deposit" )).floatValue();

Account acc = new Account(0f,lineOfCredit);

addObjectToAssert( "balance" , new Float(acc.getBalance()));

}

protected void initContext() {

initTestData( "AccountTest" );

}

}

Inherits from junit.framework.TestCase DDTUnit definition file: DDT-AccountTest.xml

DDTUnit – Pros & Cons

Pros

Complete separation of data and logic; separate files

Allows the cleanest Java source code

Support for complex Java types

Support for verification of exceptions

Supports global test data

Based on JUnit

Good support for grouping tests

Cons

XML syntax can be a language on its own when dealing with complex structures

Poor integration with Eclipse, programmer must rely on console outputs as well

DDTUnit – A closer look http://www.flickr.com/photos/xfrf/2260850105/ by xfrf

DDTUnit Example: Complex object with a string constructor

Class constructor

public ObjectName(String name) { ... }

Inside DDT-<namekey>.xml file

<obj id=" jmxId " type="javax.management.ObjectName">

<item>WebSphere:type=cellManager</item>

</obj>

Inside TestCase java file

javax.management.ObjectName jmxId =

(javax.management.ObjectName)getObject(" jmxId " );

DDTUnit Example: Complex object with a complex constructor

Class constructor

public Attribute(String name, String value) {... }

< obj id= " jmxAttr " type="javax.management.Attribute" hint="call"

method="constructor">

<item type="string">fileName</item>

<item type="string"> directory< /item>

</item>

javax.management. Attribute jmxId =

(javax.management. Attribute )getObject(" jmxAttr " );

DDTUnit Example Defining a java.util.ArrayList

<obj id= “ profileLocations " type="java.util. ArrayList " hint="collection" valuetype="string">

<item>/opt/IBM/WebSphere/AppServer/profiles/s1</item>

<item>/opt/IBM/WebSphere/AppServer/profiles/s 2 </item>

<item>/opt/IBM/WebSphere/AppServer/profiles/s 3 </item>

</obj>

ArrayList <String> profileLocations =

( ArrayList <String>)getObject(" profileLocations " );

DDTUnit Example Array of complex objects

<obj id=" arrayId " type=“ java.util .A rray List" hint="collection">

<item type="javax.management.Attribute" hint="call" method="constructor">

<item type="string">fileName</item>

<item type="string">${SERVER_ROOT}/trace.log</item>

</item>

</obj>

ArrayList<Attribute > profileLocations =

( ArrayList < Attribute >)getObject(" arrayId " );

DDTUnit and Eclipse Snippets http://sourcepatch.blogspot.com/2009/08/ddtunit-and-eclipse-snippets.html

Other noteworthy frameworks

JTestCase

Similar to DDTUnit but lacks a test runner

Requires testcase to extract data from XML file and pass it to fixtures

Fit

High-level data definition using MS-Word and MS-Excel

Inadequate for unit testing, support for strings and basic numeric types

Jetif

Full replacement for JUnit + JTestCase

Lost me on “full replacement”

Resources

JUnit ( http:// www.junit.org / )

DDTUnit ( http://sourceforge.net/projects/ddtunit )

TestNG ( http://testng.org/doc/ )

JTestCase ( http://jtestcase.sourceforge.net/ )

Jetif ( http:// jetif.sourceforge.net )

FIT ( http://fit.c2.com/ )

My del.icio.us bookmarks for this presentation (tag: qse-ddt)

http://delicious.com/nastacio/qse-ddt

Data-Driven Unit Testing for Java

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