test: add unit and integration tests

domain/pom.xml

@@ -21,5 +21,33 @@
             <artifactId>slf4j-api</artifactId>
             <version>2.0.13</version>
         </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>5.14.2</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.24.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
+    <repositories>
+        <repository>
+            <id>maven_central</id>
+            <name>Maven Central</name>
+            <url>https://repo.maven.apache.org/maven2/</url>
+        </repository>
+    </repositories>
 </project>