Java Unit Test and Coverage Introduction

Copyright 2010 TCloud Computing Inc.

Java Unit Test and Coverage IntroductionAlex Su2010/07/21

Agenda

Trend Micro Confidential

• Test-driven development• Junit

• Ant Integration• Mock Object

• Mockito• Code Coverage Analysis• Coverage Tool

• Emma• Cobertura

• Case Study

Test-driven development


Test-driven development (TDD) is a software development technique that relies on the repetition of a very short development cycle

• Add a test• Run all tests and see if the new one fails• Write some code• Run the automated tests and see them succeed• Refactor code

Test-driven development - Scenario


Given/When/Then

Example 1: New lists are emptyGiven a new listThen the list should be empty.

Example 2: Lists with things in them are not empty.Given a new listWhen we add an objectThen the list should not be empty.

Test-driven development - Scenario


class ListTest { @Test public void shouldKnowWhetherItIsEmpty() { List<String> list1 = new ArrayList<String>(); assertTrue(list1.isEmpty()); List<String> list2 = new ArrayList<String>(); list2.add("element"); assertFalse(list2.isEmpty()); } }

Test-driven development


JUnit


• JUnit is a unit testing framework for the Java programming language.

• JUnit is linked as a JAR at compile-time; the framework resides under packages junit.framework for JUnit 3.8 and earlier and under org.junit for JUnit 4 and later.

JUnit


• Test RunnerA Runner runs tests. You will need to subclass Runner when using RunWith to invoke a custom runner.

• Test FixtureA test fixture represents the preparation needed to perform one or more tests

• Test CaseA test case defines the fixture to run multiple tests.

• Test SuiteA Test Suite is a Composite of Tests. It runs a collection of test cases.

Junit – Test Result


• Success

• FailureA failure is when one of your assertions fails, and your JUnit test notices and reports the fact.

• ErrorAn error is when some other Exception occurs--one you haven't tested for and didn't expect, such as a NullPointerException or an ArrayIndexOutOfBoundsException.

Junit – Annotation


• @BeforeClass• @AfterClass• @Before• @After• @Test• @Ignore

JUnit


public class DummyTest { private static List<String> list;

@BeforeClass public static void beforeClass() { list = new ArrayList<String>(); } @AfterClass public static void afterClass() { list = null; } @Before public void before() { list.add("Alex"); } @After public void after() { list.remove("Alex"); } @Test public void getElement() { String element = list.get(0); assertEquals(element, "Alex"); } @Ignore("Not Ready to Run") @Test public void notRun() { assertEquals(list.size(), 2); } @Test(expected = IndexOutOfBoundsException.class) public void getElementWithException() { list.get(1); }}

JUnit


@RunWith(Suite.class)@SuiteClasses({DummyTest1.class, DummyTest2.class})public class DummyTestSuite {}

JUnit


@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = { "classpath:appContext.xml" })public class DummyTest { @Resource private DummyService dummyService;

@Test public void createDummy() { Dummy dummy = new Dummy(); dummy.setId(ID); dummy.setName("Hermione Granger"); dummy.setDescription("Gryffindor");

dummyService.createDummy(dummy);

dummy = dummyService.getDummy(ID); assertNotNull(dummy); }}

Junit – Ant Integration


<junit showoutput="${build.test.dir}" printsummary="on" fork="yes" haltonfailure="false>

<classpath refid="classpath" /><formatter type="xml" />

<batchtest todir="${build.test.dir}"><fileset dir="${test.dir}">

<include name="**/*Test.java" /></fileset>

</batchtest></junit>

<junitreport todir="${doc.test.dir}"><fileset dir="${build.test.dir}">

<include name="**/TEST-*.xml" /></fileset> <report format="frames" todir="${doc.test.dir}" /></junitreport>

Mock Object


• supplies non-deterministic results (e.g. the current time or the current temperature);

• has states that are difficult to create or reproduce (e.g. a network error);

• is slow (e.g. a complete database, which would have to be initialized before the test);

• does not yet exist or may change behavior;• would have to include information and methods

exclusively for testing purposes (and not for its actual task).

Mock Object - Mockito


• Argument matchers • Verifying exact number of invocations / at least x /

never• Verification in order• Shorthand for mocks creation - @Mock annotation• Stubbing consecutive calls • Spying on real objects• Aliases for behavior driven development

Mock Object - Mockito


public class ListTest { private List<String> mockedList;

@Before public void initMocks() { mockedList = mock(List.class);

given(mockedList.get(0)).willReturn("first", "second"); given(mockedList.get(1)).willThrow(new IndexOutOfBoundsException()); }

@Test public void getList() { assertEquals("first", mockedList.get(0)); assertEquals("second", mockedList.get(0)); }

@Test(expected = IndexOutOfBoundsException.class) public void getListWithException() { mockedList.get(1); }}

Code Coverage Analysis


• Finding areas of a program not exercised by a set of test cases.

• Creating additional test cases to increase coverage.• Determining a quantitative measure of code

coverage, which is an indirect measure of quality. • Identifying redundant test cases that do not

increase coverage.



• Basic Metrics• Statement Coverage(Line)• Basic Block Coverage• Decision Coverage(Branch)• Condition Coverage • Multiple Condition Coverage • Condition/Decision Coverage• Modified Condition/Decision Coverage • Path Coverage



• Statement Coverage(Line)• Basic Block Coverage• Decision Coverage(Branch)• Condition Coverage • Multiple Condition Coverage

boolean a = true, b = true;if(a && b) { System.out.println("true");} else { System.out.println("false");}



• Condition/Decision Coverage(C/DC)• Modified Condition/Decision Coverage(MC/DC)

boolean a = true, b = true;if(a && b) { System.out.println("true");} else { System.out.println("false");}

if(a || b) { System.out.println("true");} else { System.out.println("false");}



• Path Coverage

X = 0

A>1

A=2 or

X > 1

X = 20

Y

Y

N

N

A = 3 and X = 5A = 0 and X = 3

A = 0 and X = 0A = 2 and X = 0

print x



• Other Metrics • Function Coverage• Data Flow Coverage • Loop Coverage • Race Coverage • Relational Operator Coverage

Coverage Tool


• Instrumentation• Source code instrumentation• Bytecode instrumentation• Runtime instrumentation

Coverage Tool


Possible feature Runtime Bytecode Source code

Gathers method coverage yes yes yes

Gathers statement coverage

line only yes yes

Gathers branch coverage indirectly yes yes

Can work without source yes yes no

Requires separate build no no yes

Requires specialised runtime

yes not accurate no

View coverage data inline with source

not accurate yes yes

Source level directives to control coverage gathering

no no yes

Runtime performace high impact variable variable

Container friendly no not accurate yes

Coverage Tool


• Reports are filterable so you can tell what needs to be evaluated for code coverage.

• offline and on-the-fly instrumentation.• Ant integration.• JUnit integration.

Coverage Tool - Emma


• Last update : 2005-06-13• Stats on both class and method coverage• Partial/fractional line coverages is unique trait -

shown in yellow when there are multiple conditions in a conditional block

• Stricter code coverage.• Integration with Eclipse available -

http://www.eclemma.org/• Better documentation than cobertura.• Instrumentation process is faster than cobertura.• Standalone library and does not have any external

dependencies.• Common public license 1.0 friendlier that GPL.

http://www.eclemma.org/

Coverage Tool - Cobertura


• Last update : 2010-03-03• GPL'd version of JCoverage (which is commercial). • Prettier reports.• Branch/block and line coverages only - no class or

method level coverage.• How many times a line has been executed• <cobertura-check> where one can specify percentage of

coverage that's a MUST or else build fails.• Data merge feature - good for QA labs... for merging

coverage data to prepare historical trend graphs.• Depends on other third party libraries.• Integration with Eclipse available -

http://ecobertura.johoop.de/

http://ecobertura.johoop.de/

Coverage Tool – Comparsion(Exception)


• Source CodeString str = "abc";System.out.println(str.substring(5));

• Decompile ResultString str = "abc";System.out.println(str.substring(5));

Coverage Tool - Comparsion(Exception)


• Emmaboolean aflag[] = ($VRc != null ? $VRc : $VRi())[3];

String s = "abc";

System.out.println(s.substring(5));

aflag[0] = true;



• Cobertura boolean flag = false; int __cobertura__branch__number__ = -1; TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 25); String str = "abc"; TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 26); System.out.println(str.substring(5)); TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 27);



• Clover__CLR3_0_217a17agbtkjkdv.R.inc(1571);__CLR3_0_217a17agbtkjkdv.R.inc(1572);String str = "abc";__CLR3_0_217a17agbtkjkdv.R.inc(1573);System.out.println(str.substring(5));

Coverage Tool – Comparsion(Loop)


• Source CodeList<String> list = new ArrayList<String>();for(String element : list) { System.out.println(element);}

• Decompile resultString element;for(Iterator iterator = list.iterator(); iterator.hasNext(); System.out.println(element))

element = (String)iterator.next();

Coverage Tool - Comparsion(Loop)


• Emmaboolean aflag[] = ($VRc != null ? $VRc : $VRi())[4];

List list = new ArrayList();

Iterator iterator = list.iterator();

aflag[0] = true;

do

{

aflag[2] = true;

if(iterator.hasNext())

{

String s = (String)iterator.next();

System.out.println(s);

aflag[1] = true;

} else

{

break;

}

} while(true);

aflag[3] = true;



• Coberturaboolean flag = false;int __cobertura__branch__number__ = -1;TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 36);List list = new ArrayList();TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 37);Iterator iterator = list.iterator();do{

TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 37);__cobertura__line__number__ = 37;__cobertura__branch__number__ = 0;if(iterator.hasNext()){

if(__cobertura__branch__number__ >= 0){

TouchCollector.touchJump("tcloud.dummy.service.CoverageTestMain", __cobertura__line__number__, __cobertura__branch__number__, false);

__cobertura__branch__number__ = -1;}String element = (String)iterator.next();TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 38);System.out.println(element);

} else{

if(__cobertura__line__number__ == 37 && __cobertura__branch__number__ == 0){

TouchCollector.touchJump("tcloud.dummy.service.CoverageTestMain", __cobertura__line__number__, __cobertura__branch__number__, true);

__cobertura__branch__number__ = -1;}TouchCollector.touch("tcloud.dummy.service.CoverageTestMain", 40);return;

}} while(true);



• Clover __CLR3_0_2145145gbu63tpg.R.inc(1462); __CLR3_0_2145145gbu63tpg.R.inc(1463); List list = new ArrayList(); __CLR3_0_2145145gbu63tpg.R.inc(1464); String element; for(Iterator iterator = list.iterator(); iterator.hasNext();

System.out.println(element)) { element = (String)iterator.next(); __CLR3_0_2145145gbu63tpg.R.inc(1465); }



• Clover with decompile resultIterator iterator;__CLR3_0_2166166gbu71moi.R.inc(1535);__CLR3_0_2166166gbu71moi.R.inc(1536);List list = new ArrayList();__CLR3_0_2166166gbu71moi.R.inc(1537);__CLR3_0_2166166gbu71moi.R.inc(1538);iterator = list.iterator();

_L4:if(iterator.hasNext()){

__CLR3_0_2166166gbu71moi.R.iget(1539);} else{

__CLR3_0_2166166gbu71moi.R.iget(1540);return;

}if(true) goto _L2; else goto _L1

_L1:break; /* Loop/switch isn't completed */

_L2:__CLR3_0_2166166gbu71moi.R.inc(1541);String element = (String)iterator.next();System.out.println(element);if(true) goto _L4; else goto _L3

_L3:


Case Study


THANK YOU!

Date post:	10-May-2015
Category:	Technology
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Java Unit Test and Coverage Introduction

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