diff --git a/code-generation/src/main/java/com/baeldung/autovalue/Person.java b/code-generation/src/main/java/com/baeldung/autovalue/Person.java new file mode 100644 index 0000000000..a5fb684596 --- /dev/null +++ b/code-generation/src/main/java/com/baeldung/autovalue/Person.java @@ -0,0 +1,38 @@ +package com.baeldung.autovalue; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; + +import com.google.auto.value.AutoValue; + +@AutoValue +public abstract class Person { + + public abstract String name(); + + public abstract List favoriteMovies(); + + public static Builder builder() { + return new AutoValue_Person.Builder(); + } + + @AutoValue.Builder + public static abstract class Builder { + + public abstract Builder name(String value); + + public abstract Builder favoriteMovies(List value); + + abstract List favoriteMovies(); + + abstract Person autoBuild(); + + public Person build() { + List favoriteMovies = favoriteMovies(); + List copy = Collections.unmodifiableList(new ArrayList<>(favoriteMovies)); + favoriteMovies(copy); + return autoBuild(); + } + } +} diff --git a/code-generation/src/test/java/com/baeldung/autovalue/PersonUnitTest.java b/code-generation/src/test/java/com/baeldung/autovalue/PersonUnitTest.java new file mode 100644 index 0000000000..fce12edafe --- /dev/null +++ b/code-generation/src/test/java/com/baeldung/autovalue/PersonUnitTest.java @@ -0,0 +1,37 @@ +package com.baeldung.autovalue; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; + +import java.util.ArrayList; +import java.util.List; + +import org.junit.Test; + +/** + * Unit Test which verifies that the {@link Person} value object creates defensive copies of its favoriteMovies list. + */ +public class PersonUnitTest { + + @Test + public void givenNewPerson_whenModifyOriginalList_thenValueObjectIsNotAlsoModified() { + // GIVEN new Person + List originalFavoriteMoviesList = new ArrayList(); + originalFavoriteMoviesList.add("Training Day"); + originalFavoriteMoviesList.add("Fast and the Furious"); + Person person = Person.builder() + .name("Dan") + .favoriteMovies(originalFavoriteMoviesList) + .build(); + + // WHEN modify original list + originalFavoriteMoviesList.add("Friday"); + + // THEN Person remains unaffected + assertFalse(person.favoriteMovies() + .contains("Friday")); + assertEquals(2, person.favoriteMovies() + .size()); + } + +}