BAEL-3091: The Prototype Pattern in Java (changed code based on valid comments from a reader)

testing-modules/junit-5-advanced/README.md

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+## Relevant Articles:
+
+- [JUnit 5 TestWatcher API](https://www.baeldung.com/junit-testwatcher)
+- [JUnit Custom Display Name Generator API](https://www.baeldung.com/junit-custom-display-name-generator)
+- [@TestInstance Annotation in JUnit 5](https://www.baeldung.com/junit-testinstance-annotation)
+

testing-modules/junit-5-advanced/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<artifactId>junit-5-advanced</artifactId>
+	<version>1.0-SNAPSHOT</version>
+	<name>junit-5-advanced</name>
+	<description>Advanced JUnit 5 Topics</description>
+
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>parent-modules</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+		<relativePath>../../</relativePath>
+	</parent>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter</artifactId>
+			<version>${junit-jupiter.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter-engine</artifactId>
+			<version>${junit-jupiter.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.junit.vintage</groupId>
+			<artifactId>junit-vintage-engine</artifactId>
+			<version>${junit.vintage.version}</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<artifactId>maven-surefire-plugin</artifactId>
+				<version>${maven-surefire-plugin.version}</version>
+			</plugin>
+		</plugins>
+	</build>
+	<properties>
+		<junit-jupiter.version>5.4.2</junit-jupiter.version>
+		<maven-surefire-plugin.version>2.21.0</maven-surefire-plugin.version>
+		<junit.vintage.version>5.4.2</junit.vintage.version>
+	</properties>
+
+</project>

testing-modules/junit-5-advanced/src/main/java/com/baeldung/failure_vs_error/SimpleCalculator.java

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+package com.baeldung.failure_vs_error;
+
+/**
+ * @author paullatzelsperger
+ * @since 2019-07-17
+ */
+public class SimpleCalculator {
+
+    public static double divideNumbers(double dividend, double divisor) {
+        if (divisor == 0) {
+            throw new ArithmeticException("Division by zero!");
+        }
+        return dividend / divisor;
+    }
+}

testing-modules/junit-5-advanced/src/main/java/com/baeldung/junit5/testinstance/Tweet.java

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+package com.baeldung.junit5.testinstance;
+
+import java.io.Serializable;
+
+public class Tweet implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+    private String id;
+    private String content;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+}

testing-modules/junit-5-advanced/src/main/java/com/baeldung/junit5/testinstance/TweetException.java

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+package com.baeldung.junit5.testinstance;
+
+public class TweetException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public TweetException(String message) {
+        super(message);
+    }
+}

testing-modules/junit-5-advanced/src/main/java/com/baeldung/junit5/testinstance/TweetSerializer.java

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+package com.baeldung.junit5.testinstance;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectOutputStream;
+
+public class TweetSerializer {
+
+    private static final int MAX_TWEET_SIZE = 1000;
+    private static final int MIN_TWEET_SIZE = 150;
+    private final Tweet tweet;
+
+    public TweetSerializer(Tweet tweet) {
+        this.tweet = tweet;
+    }
+
+    public byte[] serialize() throws IOException {
+        byte[] tweetContent = serializeTweet();
+        int totalLength = tweetContent.length;
+        validateSizeOfTweet(totalLength);
+        return tweetContent;
+    }
+
+    private void validateSizeOfTweet(int tweetSize) {
+        if (tweetSize > MAX_TWEET_SIZE) {
+            throw new TweetException("Tweet is too large");
+        }
+        if (tweetSize < MIN_TWEET_SIZE) {
+            throw new TweetException("Tweet is too small");
+        }
+    }
+
+    private byte[] serializeTweet() throws IOException {
+        try (ByteArrayOutputStream arrayOutputStream = new ByteArrayOutputStream(); 
+                ObjectOutputStream objectStream = new ObjectOutputStream(arrayOutputStream)) {
+            objectStream.writeObject(tweet);
+            return arrayOutputStream.toByteArray();
+        }
+    }
+
+}

testing-modules/junit-5-advanced/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

testing-modules/junit-5-advanced/src/test/java/com/baeldung/displayname/DisplayNameGeneratorUnitTest.java

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+package com.baeldung.displayname;
+
+import org.junit.jupiter.api.DisplayNameGeneration;
+import org.junit.jupiter.api.DisplayNameGenerator;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import java.lang.reflect.Method;
+
+@DisplayNameGeneration(DisplayNameGeneratorUnitTest.ReplaceCamelCase.class)
+class DisplayNameGeneratorUnitTest {
+
+    @Test
+    void camelCaseName() {
+    }
+
+    @Nested
+    @DisplayNameGeneration(DisplayNameGeneratorUnitTest.IndicativeSentences.class)
+    class ANumberIsFizz {
+        @Test
+        void ifItIsDivisibleByThree() {
+        }
+
+        @ParameterizedTest(name = "Number {0} is fizz.")
+        @ValueSource(ints = { 3, 12, 18 })
+        void ifItIsOneOfTheFollowingNumbers(int number) {
+        }
+    }
+
+    @Nested
+    @DisplayNameGeneration(DisplayNameGeneratorUnitTest.IndicativeSentences.class)
+    class ANumberIsBuzz {
+        @Test
+        void ifItIsDivisibleByFive() {
+        }
+
+        @ParameterizedTest(name = "Number {0} is buzz.")
+        @ValueSource(ints = { 5, 10, 20 })
+        void ifItIsOneOfTheFollowingNumbers(int number) {
+        }
+    }
+
+    static class IndicativeSentences extends ReplaceCamelCase {
+        @Override
+        public String generateDisplayNameForNestedClass(Class<?> nestedClass) {
+            return super.generateDisplayNameForNestedClass(nestedClass) + "...";
+        }
+
+        @Override
+        public String generateDisplayNameForMethod(Class<?> testClass, Method testMethod) {
+            return replaceCamelCase(testClass.getSimpleName() + " " + testMethod.getName()) + ".";
+        }
+    }
+
+    static class ReplaceCamelCase extends DisplayNameGenerator.Standard {
+        @Override
+        public String generateDisplayNameForClass(Class<?> testClass) {
+            return replaceCamelCase(super.generateDisplayNameForClass(testClass));
+        }
+
+        @Override
+        public String generateDisplayNameForNestedClass(Class<?> nestedClass) {
+            return replaceCamelCase(super.generateDisplayNameForNestedClass(nestedClass));
+        }
+
+        @Override
+        public String generateDisplayNameForMethod(Class<?> testClass, Method testMethod) {
+            return this.replaceCamelCase(testMethod.getName()) + DisplayNameGenerator.parameterTypesAsString(testMethod);
+        }
+
+        String replaceCamelCase(String camelCase) {
+            StringBuilder result = new StringBuilder();
+            result.append(camelCase.charAt(0));
+            for (int i=1; i<camelCase.length(); i++) {
+                if (Character.isUpperCase(camelCase.charAt(i))) {
+                    result.append(' ');
+                    result.append(Character.toLowerCase(camelCase.charAt(i)));
+                } else {
+                    result.append(camelCase.charAt(i));
+                }
+            }
+            return result.toString();
+        }
+    }
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/displayname/ReplaceUnderscoresGeneratorUnitTest.java

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+package com.baeldung.displayname;
+
+import org.junit.jupiter.api.*;
+
+@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
+class ReplaceUnderscoresGeneratorUnitTest {
+
+    @Nested
+    class when_doing_something {
+
+        @Test
+        void then_something_should_happen() {
+        }
+
+        @Test
+        @DisplayName("@DisplayName takes precedence over generation")
+        void override_generator() {
+        }
+    }
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/extensions/testwatcher/TestResultLoggerExtension.java

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+package com.baeldung.extensions.testwatcher;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.extension.AfterAllCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.TestWatcher;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class TestResultLoggerExtension implements TestWatcher, AfterAllCallback {
+
+    private static final Logger LOG = LoggerFactory.getLogger(TestResultLoggerExtension.class);
+
+    private List<TestResultStatus> testResultsStatus = new ArrayList<>();
+
+    private enum TestResultStatus {
+        SUCCESSFUL, ABORTED, FAILED, DISABLED;
+    }
+
+    @Override
+    public void testDisabled(ExtensionContext context, Optional<String> reason) {
+        LOG.info("Test Disabled for test {}: with reason :- {}", context.getDisplayName(), reason.orElse("No reason"));
+
+        testResultsStatus.add(TestResultStatus.DISABLED);
+    }
+
+    @Override
+    public void testSuccessful(ExtensionContext context) {
+        LOG.info("Test Successful for test {}: ", context.getDisplayName());
+
+        testResultsStatus.add(TestResultStatus.SUCCESSFUL);
+    }
+
+    @Override
+    public void testAborted(ExtensionContext context, Throwable cause) {
+        LOG.info("Test Aborted for test {}: ", context.getDisplayName());
+
+        testResultsStatus.add(TestResultStatus.ABORTED);
+    }
+
+    @Override
+    public void testFailed(ExtensionContext context, Throwable cause) {
+        LOG.info("Test Aborted for test {}: ", context.getDisplayName());
+
+        testResultsStatus.add(TestResultStatus.FAILED);
+    }
+
+    @Override
+    public void afterAll(ExtensionContext context) throws Exception {
+        Map<TestResultStatus, Long> summary = testResultsStatus.stream()
+            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
+
+        LOG.info("Test result summary for {} {}", context.getDisplayName(), summary.toString());
+    }
+
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/extensions/testwatcher/TestWatcherAPIUnitTest.java

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+package com.baeldung.extensions.testwatcher;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Assumptions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+@ExtendWith(TestResultLoggerExtension.class)
+class TestWatcherAPIUnitTest {
+
+    @Test
+    void givenFalseIsTrue_whenTestAbortedThenCaptureResult() {
+        Assumptions.assumeTrue(false);
+    }
+
+    @Disabled
+    @Test
+    void givenTrueIsTrue_whenTestDisabledThenCaptureResult() {
+        Assert.assertTrue(true);
+    }
+
+    @Test
+    void givenTrueIsTrue_whenTestAbortedThenCaptureResult() {
+        Assumptions.assumeTrue(true);
+    }
+
+    @Disabled("This test is disabled")
+    @Test
+    void givenFailure_whenTestDisabledWithReason_ThenCaptureResult() {
+        fail("Not yet implemented");
+    }
+
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/failure_vs_error/SimpleCalculatorUnitTest.java

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+package com.baeldung.failure_vs_error;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author paullatzelsperger
+ * @since 2019-07-17
+ */
+class SimpleCalculatorUnitTest {
+
+    @Test
+    void divideNumbers() {
+        double result = SimpleCalculator.divideNumbers(6, 3);
+        assertEquals(2, result);
+    }
+
+    @Test
+    @Disabled("test is expected to fail, disabled so that CI build still goes through")
+    void divideNumbers_failure() {
+        double result = SimpleCalculator.divideNumbers(6, 3);
+        assertEquals(15, result);
+    }
+
+    @Test
+    @Disabled("test is expected to raise an error, disabled so that CI build still goes through")
+    void divideNumbers_error() {
+        SimpleCalculator.divideNumbers(10, 0);
+    }
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/junit5/testinstance/AdditionUnitTest.java

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+package com.baeldung.junit5.testinstance;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class AdditionUnitTest {
+
+    private int sum = 1;
+
+    @Test
+    void addingTwoToSumReturnsThree() {
+        sum += 2;
+        assertEquals(3, sum);
+    }
+
+    @Test
+    void addingThreeToSumReturnsFour() {
+        sum += 3;
+        assertEquals(4, sum);
+    }
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/junit5/testinstance/OrderUnitTest.java

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+package com.baeldung.junit5.testinstance;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
+import org.junit.jupiter.api.Order;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+import org.junit.jupiter.api.TestMethodOrder;
+
+@TestMethodOrder(OrderAnnotation.class)
+@TestInstance(Lifecycle.PER_CLASS)
+class OrderUnitTest {
+
+    private int sum;
+
+    @BeforeAll
+    void init() {
+        sum = 1;
+    }
+
+    @Test
+    @Order(1)
+    void firstTest() {
+        sum += 2;
+        assertEquals(3, sum);
+    }
+
+    @Test
+    @Order(2)
+    void secondTest() {
+        sum += 3;
+        assertEquals(6, sum);
+    }
+
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/junit5/testinstance/TweetSerializerJUnit4UnitTest.java

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+package com.baeldung.junit5.testinstance;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class TweetSerializerJUnit4UnitTest {
+
+    private static String largeContent;
+    private static String content;
+    private static String smallContent;
+
+    private static Tweet tweet;
+
+    @Rule
+    public ExpectedException expectedException = ExpectedException.none();
+
+    @BeforeClass
+    public static void setUpFixture() throws IOException {
+        content = "Lorem ipsum dolor sit amet, consectetur adipiscing elit";
+        smallContent = "Lorem ipsum dolor";
+        largeContent = new String(Files.readAllBytes(Paths.get("src/test/resources/lorem-ipsum.txt")));
+        tweet = new Tweet();
+        tweet.setId("AX1346");
+    }
+
+    @Test
+    public void serializerThrowsExceptionWhenMessageIsTooLarge() throws IOException {
+        tweet.setContent(largeContent);
+
+        expectedException.expect(TweetException.class);
+        expectedException.expectMessage("Tweet is too large");
+
+        new TweetSerializer(tweet).serialize();
+    }
+
+    @Test
+    public void serializerThrowsExceptionWhenMessageIsTooSmall() throws IOException {
+        tweet.setContent(smallContent);
+
+        expectedException.expect(TweetException.class);
+        expectedException.expectMessage("Tweet is too small");
+
+        new TweetSerializer(tweet).serialize();
+    }
+
+    @Test
+    public void serializeTweet() throws IOException {
+        tweet.setContent(content);
+        byte[] content = new TweetSerializer(tweet).serialize();
+        assertThat(content, is(notNullValue()));
+    }
+}

testing-modules/junit-5-advanced/src/test/java/com/baeldung/junit5/testinstance/TweetSerializerUnitTest.java

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+package com.baeldung.junit5.testinstance;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.notNullValue;
+import static org.junit.Assert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+
+@TestInstance(Lifecycle.PER_CLASS)
+class TweetSerializerUnitTest {
+
+    private String largeContent;
+    private String content;
+    private String smallContent;
+
+    private Tweet tweet;
+
+    @BeforeAll
+    void setUpFixture() throws IOException {
+        content = "Lorem ipsum dolor sit amet, consectetur adipiscing elit";
+        smallContent = "Lorem ipsum dolor";
+        largeContent = new String(Files.readAllBytes(Paths.get("src/test/resources/lorem-ipsum.txt")));
+        tweet = new Tweet();
+        tweet.setId("AX1346");
+    }
+
+    @Test
+    void serializerThrowsExceptionWhenMessageIsTooLarge() throws IOException {
+        tweet.setContent(largeContent);
+
+        TweetException tweetException = assertThrows(TweetException.class, () -> new TweetSerializer(tweet).serialize());
+        assertThat(tweetException.getMessage(), is(equalTo("Tweet is too large")));
+    }
+
+    @Test
+    void serializerThrowsExceptionWhenMessageIsTooSmall() throws IOException {
+        tweet.setContent(smallContent);
+
+        TweetException tweetException = assertThrows(TweetException.class, () -> new TweetSerializer(tweet).serialize());
+        assertThat(tweetException.getMessage(), is(equalTo("Tweet is too small")));
+    }
+
+    @Test
+    void serializeTweet() throws IOException {
+        tweet.setContent(content);
+        byte[] content = new TweetSerializer(tweet).serialize();
+        assertThat(content, is(notNullValue()));
+    }
+
+}

testing-modules/junit-5-advanced/src/test/resources/lorem-ipsum.txt

@@ -0,0 +1,4 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.