Groovy testing Davide Rossi Jug Milano, 19/02/2009

Jug Milano, 19/02/2009

Contents - Groovy built-in testing framework - Unit test in Groovy: GroovyTestCase - Testing for exceptions - Groovy Mock and Stub - The Java way: easymock, jMock... - The Groovy way: using Categories - The Groovy way: using ExpandoMetaClass - The Groovy way: using Expandos and Maps - The Groovy way: using stubFor and mockFor - Testing Grails Actions - Conclusion

- Groovy built-in testing framework

- Unit test in Groovy: GroovyTestCase

- Testing for exceptions

- Groovy Mock and Stub

- The Java way: easymock, jMock...

- The Groovy way: using Categories

- The Groovy way: using ExpandoMetaClass

- The Groovy way: using Expandos and Maps

- The Groovy way: using stubFor and mockFor

- Testing Grails Actions

- Conclusion

Groovy testing framework - Groovy can be used to test Groovy and Java code - Groovy has built-in support for Junit framework - GroovyTestCase extends Junit TestCase - Adds many assertion methods (assertToString, AssertArrayEquals, shouldFail...) - Assertions are parts of the language ex: def number = 2 assert (number + 2) == 4

- Groovy can be used to test Groovy and Java code

- Groovy has built-in support for Junit framework

- GroovyTestCase extends Junit TestCase

- Adds many assertion methods (assertToString, AssertArrayEquals, shouldFail...)

- Assertions are parts of the language

ex:

def number = 2

assert (number + 2) == 4

GroovyTestCase class SimpleUnitTest extends GroovyTestCase { void testSimple() { def integerList = [1, 2, 3] assertEquals 2, integerList[1] assertEquals 6, integerList[0] + integerList[1] + integerList[2] } }

class SimpleUnitTest extends GroovyTestCase {

void testSimple() {

def integerList = [1, 2, 3]

assertEquals 2, integerList[1]

assertEquals 6, integerList[0] + integerList[1] + integerList[2]

}

}

GroovyTestCase: testing for exceptions class ClassToTest { def methodWhichThrowsException() { // Doing some work... throw new NumberFormatException("Warning!") } } void testSimple() { def objectToTest = new ClassToTest() shouldFail(NumberFormatException) { objectToTest.methodWhichThrowsException() } }

class ClassToTest {

def methodWhichThrowsException() {

// Doing some work...

throw new NumberFormatException("Warning!")

}

}

void testSimple() {

def objectToTest = new ClassToTest()

shouldFail(NumberFormatException) {

objectToTest.methodWhichThrowsException()

}

}

Mocks and Stubs - Mocks and stubs are used to substitute real collaborators of the tested class - With mocks and stubs you can unit test your code in isolation without depend form external code - stubs have weak expectations: verify state of mocked objects - mocks have strong expectations: verify state and behaviour of mocked objects

- Mocks and stubs are used to substitute real collaborators of the tested class

- With mocks and stubs you can unit test your code in isolation without depend form external code

- stubs have weak expectations: verify state of mocked objects

- mocks have strong expectations: verify state and behaviour of mocked objects

The Java way - Easymock, jMock, jMockit, Mockito... public void testGetPrice() { CurChange mockedDependency = createMock(CurChange.class); expect(mockedDependency.getPriceByEUR(EUR)).andReturn(new BigDecimal(100)); replay(mockedDependency); BigDecimal price = systemUnderTest.getPrice(EUR); assertNotNull(price); verify(mockedDependency); }

- Easymock, jMock, jMockit, Mockito...

public void testGetPrice() {

CurChange mockedDependency = createMock(CurChange.class);

expect(mockedDependency.getPriceByEUR(EUR)).andReturn(new BigDecimal(100));

replay(mockedDependency);

BigDecimal price = systemUnderTest.getPrice(EUR);

assertNotNull(price);

verify(mockedDependency);

}

The Groovy way Groovy dynamic nature allows easy mocks implementation - Mock using mockFor and stubFor - Mock using Categories - Mock using ExpandoMetaClass - Mock using Expandos and Maps

Groovy dynamic nature allows easy mocks implementation

- Mock using mockFor and stubFor

- Mock using Categories

- Mock using ExpandoMetaClass

- Mock using Expandos and Maps

Mock using mockFor and stubFor - Inspired by easyMock, with same power and semantic - Similar to Java - Can be used everywhere a mock is needed - You define expectations and verify them - Mock Groovy and Java Collaborators - Behavior specified via Closures, allowing static or calculated return values, throwing exceptions, asserting argument values... - Not dependent on any external mock library

- Inspired by easyMock, with same power and semantic

- Similar to Java

- Can be used everywhere a mock is needed

- You define expectations and verify them

- Mock Groovy and Java Collaborators

- Behavior specified via Closures, allowing static or calculated return values, throwing exceptions, asserting argument values...

- Not dependent on any external mock library

StubFor and mockFor def save = { try { def file = new File(baseDir, params.id) file.text = params.text render "success" } catch (Exception e) { render "exception ${e.message}" } }

def save = {

try {

def file = new File(baseDir, params.id)

file.text = params.text

render "success"

} catch (Exception e) {

render "exception ${e.message}"

}

}

stubFor void testSave() { def testObj = new ClassToTest() def fileMock = new StubFor(java.io.File) def resultText fileMock.demand.setText() { resultText = it } fileMock.demand.close {} fileMock.use { testObj.save() } assertEquals "Qui va il contenuto del file" , resultText }

void testSave() {

def testObj = new ClassToTest()

def fileMock = new StubFor(java.io.File)

def resultText

fileMock.demand.setText() { resultText = it }

fileMock.demand.close {}

fileMock.use {

testObj.save()

}

assertEquals "Qui va il contenuto del file" , resultText

}

mockFor def save = { def params = ['baseDir': '.', 'id': 'NuovoFile', 'text': 'Qui va il contenuto del file'] try { def file = new File(params.baseDir, params.id) file.text = params.text file.text = "Qui aggiungo testo" file.close() } catch (Exception e) { log "exception ${e.message}" } }

def save = {

def params = ['baseDir': '.', 'id': 'NuovoFile', 'text': 'Qui va il contenuto del file']

try {

def file = new File(params.baseDir, params.id)

file.text = params.text

file.text = "Qui aggiungo testo"

file.close()

} catch (Exception e) {

log "exception ${e.message}"

}

}

mockFor void testSave() { def testObj = new ClassToTest() def fileMock = new MockFor(java.io.File) def resultText1, resultText2 fileMock.demand.setText() { resultText1 = it } fileMock.demand.setText() { resultText2 = it } fileMock.demand.close(1..1) {} fileMock.use { testObj.saveForMock() } assertEquals "Qui va il contenuto del file" , resultText1 assertEquals "Qui aggiungo testo" , resultText2 }

void testSave() {

def testObj = new ClassToTest()

def fileMock = new MockFor(java.io.File)

def resultText1, resultText2

fileMock.demand.setText() { resultText1 = it }

fileMock.demand.setText() { resultText2 = it }

fileMock.demand.close(1..1) {}

fileMock.use {

testObj.saveForMock()

}

assertEquals "Qui va il contenuto del file" , resultText1

assertEquals "Qui aggiungo testo" , resultText2

}

Mocking using Categories What are Categories ? A MOP method injection technique class StringStrangeFormatUtil { def static specialFormat(String self) { if (self.size() < 10) { return &quot;***${self}***&quot; } } } use(StringStrangeFormatUtil) { println &quot;ciao&quot;.specialFormat() }

What are Categories ? A MOP method injection technique

class StringStrangeFormatUtil {

def static specialFormat(String self) {

if (self.size() < 10) {

return &quot;***${self}***&quot;

}

}

}

use(StringStrangeFormatUtil) {

println &quot;ciao&quot;.specialFormat()

}

Mocking using Categories def methodForMockUsingCategoriesOrMetaclass() { int value = collaboratorMethod() * 3 return value } def collaboratorMethod() { // Attendere prego... // Please Wait... return 10 }

def methodForMockUsingCategoriesOrMetaclass() {

int value = collaboratorMethod() * 3

return value

}

def collaboratorMethod() {

// Attendere prego...

// Please Wait...

return 10

}

Mocking using Categories class TestMockUsingCategories extends GroovyTestCase { void testMethodForMockUsingCategories() { def testObj = new ClassToTest() use(MockHelper) { def result = testObj.methodForMockUsingCategoriesOrMetaclass() assertEquals 399, result } } } class MockHelper { def static collaboratorMethod(ClassToTest self) { 133 } }

class TestMockUsingCategories extends GroovyTestCase {

void testMethodForMockUsingCategories() {

def testObj = new ClassToTest()

use(MockHelper) {

def result = testObj.methodForMockUsingCategoriesOrMetaclass()

assertEquals 399, result

}

}

}

class MockHelper {

def static collaboratorMethod(ClassToTest self) { 133 }

}

Mocking using ExpandoMetaClass void testMethodForMockUsingCategoriesOrMetaclass() { def emc = new ExpandoMetaClass(ClassToTest) emc.collaboratorMethod = { -> 133 } emc.initialize() def testObj = new ClassToTest() testObj.metaClass = emc def result = testObj.methodForMockUsingCategoriesOrMetaclass() assertEquals 399, result }

void testMethodForMockUsingCategoriesOrMetaclass() {

def emc = new ExpandoMetaClass(ClassToTest)

emc.collaboratorMethod = { -> 133 }

emc.initialize()

def testObj = new ClassToTest()

testObj.metaClass = emc

def result = testObj.methodForMockUsingCategoriesOrMetaclass()

assertEquals 399, result

}

Mocking using Expandos def saveFile(file) { file.write &quot;Testo del file.&quot; } void testSaveFile() { def fileMock = new Expando(text: &quot;, write: {text = &quot;Testo dinamico dell'Expando&quot; }) def testObj = new ClassToTest() testObj.saveFile(fileMock) assertEquals &quot;Testo dinamico dell'Expando&quot; , fileMock.text }

def saveFile(file) {

file.write &quot;Testo del file.&quot;

}

void testSaveFile() {

def fileMock = new Expando(text: &quot;, write: {text = &quot;Testo dinamico dell'Expando&quot; })

def testObj = new ClassToTest()

testObj.saveFile(fileMock)

assertEquals &quot;Testo dinamico dell'Expando&quot; , fileMock.text

}

Mocking using Maps void testSaveFile() { def text = '' def fileMock = [write : { text = &quot;Testo dinamico della mappa&quot; }] def testObj = new ClassToTest() testObj.saveFile(fileMock) assertEquals &quot;Testo dinamico della mappa&quot; , text }

void testSaveFile() {

def text = ''

def fileMock = [write : { text = &quot;Testo dinamico della mappa&quot; }]

def testObj = new ClassToTest()

testObj.saveFile(fileMock)

assertEquals &quot;Testo dinamico della mappa&quot; , text

}

Testing Grails Actions - Integration test: Grails uses a HSQL DB and injects environment objects (session, controllers...) def team1, team2, team3, team4 void setUp() { team1 = new Team(name: 'Varese', championship: 'Serie C2', city: 'Varese', supporters: 1000, foundationYear: 1910).save() .... } void tearDown() { Team.list()*.delete()

- Integration test: Grails uses a HSQL DB and injects environment objects (session, controllers...)

def team1, team2, team3, team4

void setUp() {

team1 = new Team(name: 'Varese', championship: 'Serie C2', city: 'Varese', supporters: 1000, foundationYear: 1910).save()

....

}

void tearDown() {

Team.list()*.delete()

Testing Grails Action void testSearch() { def tc = new TeamController() tc.params.championship = &quot;Serie C2 &quot; tc.search() assertEquals &quot;/team/list&quot;, tc.modelAndView.viewName assertEquals 1, tc.modelAndView.model.teamCount assertTrue tc.modelAndView.model.teamList.contains(team1) }

void testSearch() {

def tc = new TeamController()

tc.params.championship = &quot;Serie C2 &quot;

tc.search()

assertEquals &quot;/team/list&quot;, tc.modelAndView.viewName

assertEquals 1, tc.modelAndView.model.teamCount

assertTrue tc.modelAndView.model.teamList.contains(team1)

}

Conclusions - Some techniques (like Expandos or Categories) are useful when testing Groovy classes - Mocking using maps is useful when testing Java classes but you have to pass the mocked object to the Class Under Test - mockFor and stubFor are very powerful and are used as an alternative to frameworks like easymock, jMock... - more frameworks are coming (Gmock) - The future: Behavior driven development (BDD) ? easyB...

- Some techniques (like Expandos or Categories) are useful when testing Groovy classes

- Mocking using maps is useful when testing Java classes but you have to pass the mocked object to the Class Under Test

- mockFor and stubFor are very powerful and are used as an alternative to frameworks like easymock, jMock...

- more frameworks are coming (Gmock)

- The future: Behavior driven development (BDD) ? easyB...

Reference - Groovy in Action (D. Konig, A. Glover, P. King, G. Laforge, J. Skeet) – Manning - Programming Groovy – Dynamic productivity for the Java developer (Venkat Subramaniam) – Pragmatic Programmera - http://groovy.codehaus.org/Testing+Guide

- Groovy in Action (D. Konig, A. Glover, P. King, G. Laforge, J. Skeet) – Manning

- Programming Groovy – Dynamic productivity for the Java developer (Venkat Subramaniam) – Pragmatic Programmera

- http://groovy.codehaus.org/Testing+Guide