Enforcing your architecture with arch unit

Author: michaelk

archunit/.gitignore

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+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

archunit/README.md

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+# Examples for [Enforcing Your Architecture with ArchUnit](https://reflectoring.io/enforce-architecture-with-arch-unit)
+
+This repository contains the source code of the article's examples.
+The code examples and the code in the repository use Maven as a build tool and JUnit as testing framework. 
+The only exception are the code examples for using ArchUnit with Scala.

archunit/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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>io.reflectoring</groupId>
+  <artifactId>archunit</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <name>ArchUnit</name>
+  <description>Demo project for ArchUnit</description>
+
+  <properties>
+    <maven.compiler.source>19</maven.compiler.source>
+    <maven.compiler.target>19</maven.compiler.target>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>com.tngtech.archunit</groupId>
+      <artifactId>archunit-junit5</artifactId>
+      <version>1.0.1</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-engine</artifactId>
+      <version>5.8.1</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>javax.ws.rs</groupId>
+      <artifactId>javax.ws.rs-api</artifactId>
+      <version>2.1.1</version>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-api</artifactId>
+      <version>5.9.2</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+</project>

archunit/src/main/java/io/reflectoring/archunit/ArchUnitExamples.java

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+package io.reflectoring.archunit;
+
+import java.math.BigDecimal;
+
+public class ArchUnitExamples {
+
+    public void reference_deprecated_class() {
+        Dep dep = new Dep();
+    }
+
+    @Deprecated
+    public class Dep {
+
+    }
+
+    public void this_method_calls_the_wrong_BigDecimal_constructor() {
+        BigDecimal value = new BigDecimal(123.0);
+
+        // BigDecimal value = new BigDecimal("123.0"); // works!
+    }
+
+}

archunit/src/main/java/io/reflectoring/archunit/api/EmployeeController.java

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+package io.reflectoring.archunit.api;
+
+import io.reflectoring.archunit.model.EmployeeResponse;
+import io.reflectoring.archunit.service.EmployeeService;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+
+public class EmployeeController {
+
+    @GET()
+    @Path("/employees")
+    public EmployeeResponse getEmployee() {
+        EmployeeService service = new EmployeeService();
+        return service.getEmployee();
+    }
+
+    // Uncomment to cause ArchUnit rule violation
+//    @GET()
+//    @Path("/employees")
+//    public EmployeeResponse getEmployee_withViolation() {
+//        EmployeeDao dao = new EmployeeDao();
+//        Employee employee = dao.findEmployee();
+//        return new EmployeeResponse(
+//            employee.id(),
+//            employee.name(),
+//            employee.active()
+//        );
+//    }
+}

archunit/src/main/java/io/reflectoring/archunit/model/Employee.java

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+package io.reflectoring.archunit.model;
+
+public record Employee(long id, String name, boolean active) { }

archunit/src/main/java/io/reflectoring/archunit/model/EmployeeResponse.java

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+package io.reflectoring.archunit.model;
+
+public record EmployeeResponse(long id, String name, boolean active) { }

archunit/src/main/java/io/reflectoring/archunit/persistence/EmployeeDao.java

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+package io.reflectoring.archunit.persistence;
+
+import io.reflectoring.archunit.model.Employee;
+
+public class EmployeeDao {
+
+    public Employee findEmployee() {
+        return new Employee(1, "name", true);
+    }
+}

archunit/src/main/java/io/reflectoring/archunit/service/EmployeeService.java

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+package io.reflectoring.archunit.service;
+
+import io.reflectoring.archunit.model.Employee;
+import io.reflectoring.archunit.model.EmployeeResponse;
+import io.reflectoring.archunit.persistence.EmployeeDao;
+
+public class EmployeeService {
+    public EmployeeResponse getEmployee() {
+        EmployeeDao employeeDao = new EmployeeDao();
+        Employee employee = employeeDao.findEmployee();
+        return new EmployeeResponse(
+            employee.id(),
+            employee.name(),
+            employee.active()
+        );
+    }
+}

archunit/src/test/java/io/reflectoring/archunit/ArchUnitCachedTest.java

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+package io.reflectoring.archunit;
+
+import com.tngtech.archunit.core.domain.JavaClasses;
+import com.tngtech.archunit.junit.AnalyzeClasses;
+import com.tngtech.archunit.junit.ArchTest;
+import com.tngtech.archunit.lang.ArchRule;
+
+import java.math.BigDecimal;
+
+import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noClasses;
+
+    @AnalyzeClasses(packages = "io.reflectoring.archunit")
+    public class ArchUnitCachedTest {
+        @ArchTest
+        public void do_not_call_deprecated_methods_from_the_project(JavaClasses classes) {
+            ArchRule rule = noClasses().should().dependOnClassesThat().areAnnotatedWith(Deprecated.class);
+            rule.check(classes);
+        }
+
+        @ArchTest
+        public void do_not_call_constructor_cached(JavaClasses classes) {
+            ArchRule rule = noClasses().should().callConstructor(BigDecimal.class, double.class);
+            rule.check(classes);
+        }
+    }