Unit testing a Spring Boot project architecture with ArchUnit

When building software, development teams typically define a set of guidelines and conventions for coding that are considered best practices.

These are methods that are usually documented and communicated to the entire development team that adopted them. However, during development, developers can break these guidelines, which are found during code reviews or through code quality checkers.

Therefore, an important aspect is to automate these directives as much as possible throughout the project architecture to optimize checks.

We can implement these guidelines as verifiable JUnit tests using  ArchUnit . This ensures that the build of the software version is stopped in the event of an architecture violation.

ArchUnit   is a free, simple and extensible library for testing the architecture of your Java code for use in any simple Java unit testing environment. That is, ArchUnit can check dependencies between packages and classes, levels and slices, check circular dependencies, and much more. It does this by parsing a given Java bytecode and importing all classes into the Java code structure.  

ArchUnit , :

. ArchUnit.

ArchUnit JUnit 5, Maven Central: 

pom.xml

XML

<dependency>
    <groupId>com.tngtech.archunit</groupId>
    <artifactId>archunit-junit5</artifactId>
    <version>0.14.1</version>
    <scope>test</scope>
</dependency>

build.gradle

Groovy

dependencies { 
  testImplementation 'com.tngtech.archunit:archunit-junit5:0.14.1' 
} } 

Java

class ArchunitApplicationTests {

  private JavaClasses importedClasses;

  @BeforeEach
  public void setup() {
        importedClasses = new ClassFileImporter()
                .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
                .importPackages("com.springboot.testing.archunit");
    }

  @Test
  void servicesAndRepositoriesShouldNotDependOnWebLayer() {

      noClasses()
                .that().resideInAnyPackage("com.springboot.testing.archunit.service..")
                .or().resideInAnyPackage("com.springboot.testing.archunit.repository..")
                .should()
                .dependOnClassesThat()
                .resideInAnyPackage("com.springboot.testing.archunit.controller..")
                .because("Services and repositories should not depend on web layer")
                .check(importedClasses);
    }
}

-.

class ArchunitApplicationTests {

  private JavaClasses importedClasses;

  @BeforeEach
    public void setup() {
        importedClasses = new ClassFileImporter()
                .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
                .importPackages("com.springboot.testing.archunit");
    }
    @Test
    void serviceClassesShouldOnlyBeAccessedByController() {
        classes()
                .that().resideInAPackage("..service..")
                .should().onlyBeAccessed().byAnyPackage("..service..", "..controller..")
                .check(importedClasses);
    }
}

ArchUnit API-, DSL, , , .  .

( AspectJ Pointcuts). 

Java

class ArchunitApplicationTests {
  
  private JavaClasses importedClasses;

  @BeforeEach
  public void setup() {
    importedClasses = new ClassFileImporter()
        importedClasses = new ClassFileImporter()
                .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
                .importPackages("com.springboot.testing.archunit");
  }

    @Test
    void serviceClassesShouldBeNamedXServiceOrXComponentOrXServiceImpl() {
        classes()
                .that().resideInAPackage("..service..")
                .should().haveSimpleNameEndingWith("Service")
                .orShould().haveSimpleNameEndingWith("ServiceImpl")
                .orShould().haveSimpleNameEndingWith("Component")
                .check(importedClasses);
    }

    @Test
    void repositoryClassesShouldBeNamedXRepository() {
        classes()
                .that().resideInAPackage("..repository..")
                .should().haveSimpleNameEndingWith("Repository")
                .check(importedClasses);
    }
    @Test
    void controllerClassesShouldBeNamedXController() {
        classes()
                .that().resideInAPackage("..controller..")
                .should().haveSimpleNameEndingWith("Controller")
                .check(importedClasses);
    }
}

— . , Service, Component . .

Java

class ArchunitApplicationTests {
  private JavaClasses importedClasses;

  @BeforeEach
  public void setup() {
      importedClasses = new ClassFileImporter()
              .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
              .importPackages("com.springboot.testing.archunit");
  }

  @Test
  void fieldInjectionNotUseAutowiredAnnotation() {

      noFields()
              .should().beAnnotatedWith(Autowired.class)
              .check(importedClasses);
  }
  @Test
  void repositoryClassesShouldHaveSpringRepositoryAnnotation() {
      classes()
              .that().resideInAPackage("..repository..")
              .should().beAnnotatedWith(Repository.class)
              .check(importedClasses);
  }
  @Test
  void serviceClassesShouldHaveSpringServiceAnnotation() {
      classes()
              .that().resideInAPackage("..service..")
              .should().beAnnotatedWith(Service.class)
              .check(importedClasses);
  }
}

API ArchUnit Lang Java.  , , .

class ArchunitApplicationTests {

	private JavaClasses importedClasses;

	@BeforeEach
  public void setup() {
        importedClasses = new ClassFileImporter()
                .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
                .importPackages("com.springboot.testing.archunit");
    }
    @Test
    void layeredArchitectureShouldBeRespected() {

					layeredArchitecture()
                .layer("Controller").definedBy("..controller..")
                .layer("Service").definedBy("..service..")
                .layer("Repository").definedBy("..repository..")
                .whereLayer("Controller").mayNotBeAccessedByAnyLayer()
                .whereLayer("Service").mayOnlyBeAccessedByLayers("Controller")
                .whereLayer("Repository").mayOnlyBeAccessedByLayers("Service")
                .check(importedClasses);
    }
}

Spring Boot , .

ArchUnit offers a set of functions to check if your layered architecture is adhered to. These tests provide automatic assurances that access and use are maintained within the limits you set. Therefore, you can write your own rules. In this article, we have described several rules. The official documentation of ArchUnit introduces many more possibilities.

The complete source code of the examples can be found in my  GitHub repository .