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Mockito –带有注释和静态方法的额外接口

發布時間：2023/12/3 编程问答 33 豆豆

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在代碼中，我最近遇到了一段非常糟糕的代碼，這些代碼基于對對象執行某些操作的類轉換。當然，代碼需要重構，但是如果您首先沒有對該功能進行單元測試，則有時您可能無法做到/或者不想這樣做（這應該是可以理解的）。在下面的文章中，我將展示如何測試這種代碼，如何重構它以及實際上我對這種代碼的看法。

讓我們看一下項目結構：

如關于Mocktio的JAXB答復REPOSTS_DEEP_STUBS的帖子所述，在com.blogspot.toomuchcoding.model包中，我們再次使用JAXB編譯器生成了JAXB生成的類。讓我們省略對pom.xml文件的討論，因為它與上一篇文章完全相同。

在com.blogspot.toomuchcoding.adapter包中，我們在JAXB PlayerDetails類上具有適配器，該類提供對Player接口的訪問。有：

CommonPlayerAdapter.java

package com.blogspot.toomuchcoding.adapter;import com.blogspot.toomuchcoding.model.Player; import com.blogspot.toomuchcoding.model.PlayerDetails;/*** User: mgrzejszczak* Date: 09.06.13* Time: 15:42*/ public class CommonPlayerAdapter implements Player {private final PlayerDetails playerDetails;public CommonPlayerAdapter(PlayerDetails playerDetails){this.playerDetails = playerDetails;}@Overridepublic void run() {System.out.printf("Run %s. Run!%n", playerDetails.getName());}public PlayerDetails getPlayerDetails() {return playerDetails;} }

DefencePlayerAdapter.java

package com.blogspot.toomuchcoding.adapter;import com.blogspot.toomuchcoding.model.DJ; import com.blogspot.toomuchcoding.model.DefensivePlayer; import com.blogspot.toomuchcoding.model.JavaDeveloper; import com.blogspot.toomuchcoding.model.PlayerDetails;/*** User: mgrzejszczak* Date: 09.06.13* Time: 15:42*/ public class DefencePlayerAdapter extends CommonPlayerAdapter implements DefensivePlayer, DJ, JavaDeveloper {public DefencePlayerAdapter(PlayerDetails playerDetails){super(playerDetails);}@Overridepublic void defend(){System.out.printf("Defence! %s. Defence!%n", getPlayerDetails().getName());}@Overridepublic void playSomeMusic() {System.out.println("Oops I did it again...!");}@Overridepublic void doSomeSeriousCoding() {System.out.println("System.out.println(\"Hello world\");");} }

OffensivePlayerAdapter.java

package com.blogspot.toomuchcoding.adapter;import com.blogspot.toomuchcoding.model.OffensivePlayer; import com.blogspot.toomuchcoding.model.PlayerDetails;/*** User: mgrzejszczak* Date: 09.06.13* Time: 15:42*/ public class OffensivePlayerAdapter extends CommonPlayerAdapter implements OffensivePlayer {public OffensivePlayerAdapter(PlayerDetails playerDetails){super(playerDetails);}@Overridepublic void shoot(){System.out.printf("%s Shooooot!.%n", getPlayerDetails().getName());} }

好的，現在讓我們轉到更有趣的部分。讓我們假設我們有一個非常簡單的玩家工廠：

PlayerFactoryImpl.java

package com.blogspot.toomuchcoding.factory;import com.blogspot.toomuchcoding.adapter.CommonPlayerAdapter; import com.blogspot.toomuchcoding.adapter.DefencePlayerAdapter; import com.blogspot.toomuchcoding.adapter.OffensivePlayerAdapter; import com.blogspot.toomuchcoding.model.Player; import com.blogspot.toomuchcoding.model.PlayerDetails; import com.blogspot.toomuchcoding.model.PositionType;/*** User: mgrzejszczak* Date: 09.06.13* Time: 15:53*/public class PlayerFactoryImpl implements PlayerFactory {@Overridepublic Player createPlayer(PositionType positionType) {PlayerDetails player = createCommonPlayer(positionType);switch (positionType){case ATT:return new OffensivePlayerAdapter(player);case MID:return new OffensivePlayerAdapter(player);case DEF:return new DefencePlayerAdapter(player);case GK:return new DefencePlayerAdapter(player);default:return new CommonPlayerAdapter(player);}}private PlayerDetails createCommonPlayer(PositionType positionType){PlayerDetails playerDetails = new PlayerDetails();playerDetails.setPosition(positionType);return playerDetails;} }

好的，我們有一家制造Player的工廠。讓我們看一下使用工廠的服務：

PlayerServiceImpl.java

package com.blogspot.toomuchcoding.service;import com.blogspot.toomuchcoding.factory.PlayerFactory; import com.blogspot.toomuchcoding.model.*;/*** User: mgrzejszczak* Date: 08.06.13* Time: 19:02*/ public class PlayerServiceImpl implements PlayerService {private PlayerFactory playerFactory;@Overridepublic Player playAGameWithAPlayerOfPosition(PositionType positionType) {Player player = playerFactory.createPlayer(positionType);player.run();performAdditionalActions(player);return player;}private void performAdditionalActions(Player player) {if(player instanceof OffensivePlayer){OffensivePlayer offensivePlayer = (OffensivePlayer) player;performAdditionalActionsForTheOffensivePlayer(offensivePlayer);}else if(player instanceof DefensivePlayer){DefensivePlayer defensivePlayer = (DefensivePlayer) player;performAdditionalActionsForTheDefensivePlayer(defensivePlayer);}}private void performAdditionalActionsForTheOffensivePlayer(OffensivePlayer offensivePlayer){offensivePlayer.shoot();}private void performAdditionalActionsForTheDefensivePlayer(DefensivePlayer defensivePlayer){defensivePlayer.defend();try{DJ dj = (DJ)defensivePlayer;dj.playSomeMusic();JavaDeveloper javaDeveloper = (JavaDeveloper)defensivePlayer;javaDeveloper.doSomeSeriousCoding();}catch(ClassCastException exception){System.err.println("Sorry, I can't do more than just play football...");}}public PlayerFactory getPlayerFactory() {return playerFactory;}public void setPlayerFactory(PlayerFactory playerFactory) {this.playerFactory = playerFactory;} }

讓我們承認吧……這段代碼很糟糕。在內部，當您查看它時（無論它是否使用了 operator 實例），您都認為它是邪惡的。正如您在代碼中看到的那樣，我們正在進行一些類強制轉換……我們到底如何進行測試？在大多數測試框架中，您無法對模擬進行此類類轉換，因為它們是使用CGLIB庫構建的，并且可能會拋出一些ClassCastExceptions。您仍然無法返回模擬和真實的實現（假設這些模擬和構建不會在構建過程中執行任何丑陋的工作），并且它實際上可以工作，但仍然如此–這是錯誤的代碼

自帶的Mockito給救援（雖然你不應該過度使用此功能-事實上，如果你需要使用它，請考慮重構它）與其extraInterfaces特點：

extraInterfaces

MockSettings extraInterfaces （java.lang.Class <？>…接口）

指定模擬應實現的額外接口。對于遺留代碼或某些極端情況可能很有用。有關背景信息，請參見此處的問題51。此神秘功能應經常使用。被測對象應該確切知道其協作者和依賴性。如果您碰巧經常使用它，請確保您確實在生成簡單，干凈且可讀的代碼。

例子：

Foo foo = mock(Foo.class, withSettings().extraInterfaces(Bar.class, Baz.class));//now, the mock implements extra interfaces, so following casting is possible:Bar bar = (Bar) foo;Baz baz = (Baz) foo;

參數：

interfaces –應該實現的額外接口。

返回值：設置實例，以便您可以流暢地指定其他設置
現在讓我們看一下測試：

PlayerServiceImplTest.java

package com.blogspot.toomuchcoding.service;import com.blogspot.toomuchcoding.factory.PlayerFactory; import com.blogspot.toomuchcoding.model.*; import org.junit.Test; import org.junit.runner.RunWith; import org.mockito.InjectMocks; import org.mockito.Mock; import org.mockito.invocation.InvocationOnMock; import org.mockito.runners.MockitoJUnitRunner; import org.mockito.stubbing.Answer;import static org.hamcrest.CoreMatchers.is; import static org.junit.Assert.assertThat; import static org.mockito.BDDMockito.*;/*** User: mgrzejszczak* Date: 08.06.13* Time: 19:26*/ @RunWith(MockitoJUnitRunner.class) public class PlayerServiceImplTest {@MockPlayerFactory playerFactory;@InjectMocksPlayerServiceImpl objectUnderTest;@Mock(extraInterfaces = {DJ.class, JavaDeveloper.class})DefensivePlayer defensivePlayerWithDjAndJavaDevSkills;@MockDefensivePlayer defensivePlayer;@MockOffensivePlayer offensivePlayer;@MockPlayer commonPlayer;@Testpublic void shouldReturnOffensivePlayerThatRan() throws Exception {//givengiven(playerFactory.createPlayer(PositionType.ATT)).willReturn(offensivePlayer);//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(PositionType.ATT);//thenassertThat(createdPlayer == offensivePlayer, is(true));verify(offensivePlayer).run();}@Testpublic void shouldReturnDefensivePlayerButHeWontBeADjNorAJavaDev() throws Exception {//givengiven(playerFactory.createPlayer(PositionType.GK)).willReturn(defensivePlayer);//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(PositionType.GK);//thenassertThat(createdPlayer == defensivePlayer, is(true));verify(defensivePlayer).run();verify(defensivePlayer).defend();verifyNoMoreInteractions(defensivePlayer);}@Testpublic void shouldReturnDefensivePlayerBeingADjAndAJavaDev() throws Exception {//givengiven(playerFactory.createPlayer(PositionType.GK)).willReturn(defensivePlayerWithDjAndJavaDevSkills);doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("Hit me baby one more time!");return null;}}).when(((DJ) defensivePlayerWithDjAndJavaDevSkills)).playSomeMusic();doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("public static void main(String... args){\n}");return null;}}).when(((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills)).doSomeSeriousCoding();//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(PositionType.GK);//thenassertThat(createdPlayer == defensivePlayerWithDjAndJavaDevSkills, is(true));verify(defensivePlayerWithDjAndJavaDevSkills).run();verify(defensivePlayerWithDjAndJavaDevSkills).defend();verify((DJ) defensivePlayerWithDjAndJavaDevSkills).playSomeMusic();verify((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills).doSomeSeriousCoding();}@Testpublic void shouldReturnDefensivePlayerBeingADjAndAJavaDevByUsingWithSettings() throws Exception {//givenDefensivePlayer defensivePlayerWithDjAndJavaDevSkills = mock(DefensivePlayer.class, withSettings().extraInterfaces(DJ.class, JavaDeveloper.class));given(playerFactory.createPlayer(PositionType.GK)).willReturn(defensivePlayerWithDjAndJavaDevSkills);doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("Hit me baby one more time!");return null;}}).when(((DJ) defensivePlayerWithDjAndJavaDevSkills)).playSomeMusic();doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("public static void main(String... args){\n}");return null;}}).when(((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills)).doSomeSeriousCoding();//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(PositionType.GK);//thenassertThat(createdPlayer == defensivePlayerWithDjAndJavaDevSkills, is(true));verify(defensivePlayerWithDjAndJavaDevSkills).run();verify(defensivePlayerWithDjAndJavaDevSkills).defend();verify((DJ) defensivePlayerWithDjAndJavaDevSkills).playSomeMusic();verify((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills).doSomeSeriousCoding();}@Testpublic void shouldReturnCommonPlayer() throws Exception {//givengiven(playerFactory.createPlayer(null)).willReturn(commonPlayer);//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(null);//thenassertThat(createdPlayer, is(commonPlayer));} }

這里有很多測試，所以讓我們看一下最有趣的測試。但是在開始之前，我們先：提供@RunWith（MockitoJUnitRunner.class）批注，它使我們能夠使用Mockito批注，例如@Mock和@InjectMocks 。

說到哪個@Mock注釋會創建一個Mock，而@InjectMocks則通過構造函數或setter注入所有模擬（這太棒了嗎？）。

對于防御性玩家，我們使用注解extraInterfaces的extra元素，該元素為給定的Mock提供其他接口。您還可以編寫（可以在shouldReturnDefensivePlayerBeingADjAndAJavaDevByUsingWithSettings測試中找到的內容）：

DefensivePlayer defensivePlayerWithDjAndJavaDevSkills = mock(DefensivePlayer.class, withSettings().extraInterfaces(DJ.class, JavaDeveloper.class));

讓我們仔細看看為與DefensivePlayer相關的功能和被測函數的轉換部分編寫的測試：

@Testpublic void shouldReturnDefensivePlayerBeingADjAndAJavaDev() throws Exception {//givengiven(playerFactory.createPlayer(PositionType.GK)).willReturn(defensivePlayerWithDjAndJavaDevSkills);doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("Hit me baby one more time!");return null;}}).when(((DJ) defensivePlayerWithDjAndJavaDevSkills)).playSomeMusic();doAnswer(new Answer<Object>() {@Overridepublic Object answer(InvocationOnMock invocationOnMock) throws Throwable {System.out.println("public static void main(String... args){\n}");return null;}}).when(((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills)).doSomeSeriousCoding();//whenPlayer createdPlayer = objectUnderTest.playAGameWithAPlayerOfPosition(PositionType.GK);//thenassertThat(createdPlayer == defensivePlayerWithDjAndJavaDevSkills, is(true));verify(defensivePlayerWithDjAndJavaDevSkills).run();verify(defensivePlayerWithDjAndJavaDevSkills).defend();verify((DJ) defensivePlayerWithDjAndJavaDevSkills).playSomeMusic();verify((JavaDeveloper) defensivePlayerWithDjAndJavaDevSkills).doSomeSeriousCoding();}

我們正在使用BDDMockito靜態方法，如給定（...）。willReturn（...）。willAnswer（...）等。然后，將空方法與自定義Anwsers結合使用。在下一行中，您可以看到，為了存根另一個接口的方法，必須將模擬轉換為給定的接口。這與驗證階段有關，在該階段，我不檢查是否已執行方法，您必須將模擬轉換為給定的接口。

您可以通過從工廠返回一個實際的實現來改進測試，或者如果創建一個繁瑣的操作，則可以返回這種實現的模擬。我想在這里展示的是如何在Mockito中使用額外的接口（也許我的用例不是最好的用例）。無論如何，測試中提出的實現都是不好的，所以我們應該考慮重構它的方法……

一種想法可能是，假設在Service中完成的附加邏輯是對象創建的一部分，將代碼原樣移至工廠：

PlayFactoryImplWithFieldSettingLogic.java

package com.blogspot.toomuchcoding.factory;import com.blogspot.toomuchcoding.adapter.CommonPlayerAdapter; import com.blogspot.toomuchcoding.adapter.DefencePlayerAdapter; import com.blogspot.toomuchcoding.adapter.OffensivePlayerAdapter; import com.blogspot.toomuchcoding.model.*;/*** User: mgrzejszczak* Date: 09.06.13* Time: 15:53*/public class PlayerFactoryImplWithFieldSettingLogic implements PlayerFactory {@Overridepublic Player createPlayer(PositionType positionType) {PlayerDetails player = createCommonPlayer(positionType);switch (positionType){case ATT:return createOffensivePlayer(player);case MID:return createOffensivePlayer(player);case DEF:return createDefensivePlayer(player);case GK:return createDefensivePlayer(player);default:return new CommonPlayerAdapter(player);}}private Player createDefensivePlayer(PlayerDetails player) {DefencePlayerAdapter defencePlayerAdapter = new DefencePlayerAdapter(player);defencePlayerAdapter.defend();defencePlayerAdapter.playSomeMusic();defencePlayerAdapter.doSomeSeriousCoding();return defencePlayerAdapter;}private OffensivePlayer createOffensivePlayer(PlayerDetails player) {OffensivePlayer offensivePlayer = new OffensivePlayerAdapter(player);offensivePlayer.shoot();return offensivePlayer;}private PlayerDetails createCommonPlayer(PositionType positionType){PlayerDetails playerDetails = new PlayerDetails();playerDetails.setPosition(positionType);return playerDetails;} }

這樣就沒有強制轉換代碼是真正干凈的。現在，PlayerService如下所示：

PlayerServiceImplWIthoutUnnecessaryLogic.java

隨之而來的問題是，您的代碼庫中是否甚至需要這種方法……

總結一下，我希望我能展示如何：

使用MockitoJUnitRunner以干凈的方式注入模擬
使用注釋或靜態方法添加可以被您的模擬使用的額外接口
使用BDDMockito執行方法存根
帶有自定義答案的存根無效方法
附加接口的存根和驗證方法
重構使用類強制轉換的代碼

這些源可在TooMuchCoding Bitbucket存儲庫和TooMuchCoding Github存儲庫中找到。

參考： Mockito –來自我們的JCG合作伙伴 Marcin Grzejszczak（位于Blog上）的具有注釋和靜態方法的Extra Interfaces，用于編碼癮君子博客。

翻譯自: https://www.javacodegeeks.com/2013/06/mockito-extra-interfaces-with-annotations-and-static-methods.html

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