feat: add ArchUnit to sticker-award

sticker-award/pom.xml

@@ -121,6 +121,14 @@
             <artifactId>mockito-core</artifactId>
             <scope>test</scope>
         </dependency>
+
+        <!-- ArchUnit for architecture testing -->
+        <dependency>
+            <groupId>com.tngtech.archunit</groupId>
+            <artifactId>archunit-junit5</artifactId>
+            <version>1.3.0</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

sticker-award/src/test/java/com/datadoghq/stickerlandia/stickeraward/ArchitectureTest.java

@@ -0,0 +1,68 @@
+package com.datadoghq.stickerlandia.stickeraward;
+
+import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noClasses;
+
+import com.tngtech.archunit.core.domain.JavaClasses;
+import com.tngtech.archunit.core.importer.ClassFileImporter;
+import com.tngtech.archunit.lang.ArchRule;
+import org.junit.jupiter.api.Test;
+
+/**
+ * ArchUnit tests to validate architectural rules based on the CodeQL arch tests. These tests ensure
+ * domain boundaries are respected and REST API classes don't directly import entity types.
+ */
+public class ArchitectureTest {
+
+    private static final JavaClasses classes =
+            new ClassFileImporter().importPackages("com.datadoghq.stickerlandia.stickeraward");
+
+    /**
+     * Cross-Domain Boundary Violations. Based on cross-domain-issues.ql Ensures sticker and award
+     * domains don't import from each other.
+     */
+    @Test
+    void sticker_domain_should_not_import_award_domain() {
+        ArchRule rule =
+                noClasses()
+                        .that()
+                        .resideInAPackage("..sticker..")
+                        .should()
+                        .dependOnClassesThat()
+                        .resideInAPackage("..award..")
+                        .because("Sticker domain should not import from award domain.");
+
+        rule.check(classes);
+    }
+
+    @Test
+    void award_domain_should_not_import_sticker_domain() {
+        ArchRule rule =
+                noClasses()
+                        .that()
+                        .resideInAPackage("..award..")
+                        .should()
+                        .dependOnClassesThat()
+                        .resideInAPackage("..sticker..")
+                        .because("Award domain should not import from sticker domain.");
+
+        rule.check(classes);
+    }
+
+    /**
+     * REST API classes should not import entity types. Based on rest-api-no-entities.ql and
+     * rest-api-imports-simple.ql Ensures REST resources don't directly use entity classes.
+     */
+    @Test
+    void rest_api_should_not_import_entities() {
+        ArchRule rule =
+                noClasses()
+                        .that()
+                        .haveSimpleNameEndingWith("Resource")
+                        .should()
+                        .dependOnClassesThat()
+                        .resideInAPackage("..entity..")
+                        .because("REST API classes should not import entity types.");
+
+        rule.check(classes);
+    }
+}