Isolating legacy code with ArchUnit tests

// gradle 
dependencies {   
  testImplementation 'com.tngtech.archunit:archunit-junit5:0.20.1' 
}

@Test
public void version2PackagesShouldNotDependOnLegacyPackages() {
    // first declare the rule
    var isolatedVersion2 = noClasses()
            .that()
            .resideInAPackage("com.acme.webapp.v2..") // the trailing dot tells ArchUnit to match all sub-packages as well
            .should()
            .dependOnClassesThat().resideInAPackage("com.acme.webapp.legacy..");

    // second define on which classes the rule should be applied
    var webapp = new ClassFileImporter()
            .withImportOption(new ImportOption.DoNotIncludeTests())
            .importPackages("com.acme.webapp");
            
    // finally run the check
    isolatedVersion2.check(webapp);
}

DescribedPredicate<JavaClass> legacyPackagesWithAcceptedDependencies =
    new DescribedPredicate<>("reside in legacy package"){
        String[] acceptedDependencies = { "OrganizationDto", "IdentityContext" };

        @Override
        public boolean apply(JavaClass input) {
            var isAnAcceptedDependency = Arrays
                    .stream(acceptedDependencies)
                    .anyMatch(acceptedDependency -> input.getSimpleName().equals(acceptedDependency));

            return !isAnAcceptedDependency && input.getPackageName().startsWith("com.acme.webapp.legacy");
        }
    };

 package architecture;

  import com.tngtech.archunit.base.DescribedPredicate;
  import com.tngtech.archunit.core.domain.JavaClass;
  import com.tngtech.archunit.core.importer.ClassFileImporter;
  import com.tngtech.archunit.core.importer.ImportOption;
  import org.junit.jupiter.api.Test;

  import java.util.Arrays;

  import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noClasses;

  public class LegacyIsolationTests {
      DescribedPredicate<JavaClass> legacyPackagesWithAcceptedDependencies =
              new DescribedPredicate<>("reside in legacy package"){
                  String[] acceptedDependencies = { "OrganizationDto", "IdentityContext" };

                  @Override
                  public boolean apply(JavaClass input) {
                      var isAnAcceptedDependency = Arrays
                              .stream(acceptedDependencies)
                              .anyMatch(acceptedDependency -> input.getSimpleName().equals(acceptedDependency));

                      return !isAnAcceptedDependency && input.getPackageName().startsWith("com.acme.webapp.legacy");
                  }
              };

      @Test
      public void version2PackagesShouldNotDependOnLegacyPackages() {

          var isolatedVersion2 = noClasses()
                  .that()
                  .resideInAPackage("com.acme.webapp.v2..")
                  .should()
                  .dependOnClassesThat(legacyPackagesWithAcceptedDependencies);

          var webapp = new ClassFileImporter()
                  .withImportOption(new ImportOption.DoNotIncludeTests())
                  .importPackages("com.acme.webapp");

          isolatedVersion2.check(webapp);
      }
  }