Test/architecture test

README.md

@@ -47,6 +47,8 @@ Pipeline
   ↓
 FilterChain
   ↓
+Router
+  ↓
 Plugin
   ↓
 HttpResponseWriter

pom.xml

@@ -35,6 +35,12 @@
             <version>${mockito.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.tngtech.archunit</groupId>
+            <artifactId>archunit</artifactId>
+            <version>1.4.1</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.yaml</groupId>
             <artifactId>snakeyaml</artifactId>

src/test/java/org/juv25d/ArchitectureTest.java

@@ -0,0 +1,172 @@
+package org.juv25d;
+
+import com.tngtech.archunit.core.domain.JavaClasses;
+import com.tngtech.archunit.core.importer.ClassFileImporter;
+import com.tngtech.archunit.core.importer.ImportOption;
+
+import com.tngtech.archunit.lang.syntax.ArchRuleDefinition;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+
+import static com.tngtech.archunit.core.domain.JavaClass.Predicates.resideInAPackage;
+import static com.tngtech.archunit.core.domain.JavaClass.Predicates.simpleName;
+
+/**
+ * This system follows a specific lifecycle where an HTTP request is processed through specialized layers.
+ * To maintain a clean architecture, the core principle is that lower layers must never depend on higher layers.
+ * While the flow is not strictly linear—for instance, filters must call the chain to proceed—these rules ensure that
+ * dependencies only move in authorized directions and that components do not "skip" steps unnecessarily
+ *
+ * The request lifecycle is designed to follow this strict flow: (Runtime Flow)
+ *
+ * Client
+ * ↓
+ * ServerSocket
+ * ↓
+ * ConnectionHandler (Virtual Thread)
+ * ↓
+ * Pipeline
+ * ↓
+ * FilterChain
+ * ↓
+ * Router
+ * ↓
+ * Plugin
+ * ↓
+ * HttpResponseWriter
+ * ↓
+ * Client
+ *
+ * Note: This describes the runtime execution flow, not direct code dependencies.
+ * Dependencies are allowed for bootstrapping and controlled object creation,
+ * but must never violate the downward lifecycle direction.
+ */
+
+public class ArchitectureTest {
+
+    private static JavaClasses importedClasses;
+
+
+    @BeforeAll
+    static void setup() {
+        importedClasses = new ClassFileImporter()
+            .withImportOption(ImportOption.Predefined.DO_NOT_INCLUDE_TESTS)
+            .importPackages("org.juv25d");
+    }
+    /**
+     *  This rule ensures that only the Server and its associated factories can initiate a ConnectionHandler.
+     *  This prevents other parts of the application from accidentally manipulating direct client connections.
+     */
+    @Test
+    void connectionHandlerAccessRule () {
+        ArchRuleDefinition.classes()
+            .that().haveSimpleName("ConnectionHandler")
+            .should().onlyBeAccessed().byClassesThat(
+                simpleName("Server")
+                    .or(simpleName("ConnectionHandler"))
+                    .or(simpleName("DefaultConnectionHandlerFactory"))
+                    .or(simpleName("ConnectionHandlerFactory")))
+            .as("ConnectionHandler access rule")
+            .because("ConnectionHandler should only be accessed by server, connectionhandler or its factories")
+            .check(importedClasses);
+    }
+
+    /**
+     * Only the network layer (ConnectionHandler) or the application's startup class (App) may interact with the Pipeline.
+     * This guarantees that the execution chain remains intact and is not modified during an active request.
+     */
+    @Test
+    void pipelineAccessRule () {
+        ArchRuleDefinition.classes()
+            .that().haveSimpleName("Pipeline")
+            .should().onlyBeAccessed().byClassesThat(
+                simpleName("ConnectionHandler")
+                    .or(simpleName("ConnectionHandlerFactory"))
+                    .or(simpleName("DefaultConnectionHandlerFactory"))
+                    .or(simpleName("Pipeline"))
+                    .or(simpleName("App")) // App handles bootstrapping and wiring of the Pipeline during startup. This should stay.
+                    .or(simpleName("Bootstrap")))
+            .as("Pipeline access rule")
+            .because("Pipeline should only be accessed by ConnectionHandler, App, Bootstrap during setup")
+            .check(importedClasses);
+    }
+
+
+    /**
+     * The FilterChain is created by the Pipeline and triggered by the ConnectionHandler.
+     * This rule also allows individual filters to access the chain.
+     */
+    @Test
+    void filterChainRule () {
+        ArchRuleDefinition.classes()
+            .that().haveSimpleName("FilterChain")
+            .should().onlyBeAccessed().byClassesThat(
+                simpleName("Pipeline")
+                    .or(simpleName("FilterChain"))
+                    .or(simpleName("FilterChainImpl"))
+                    .or(resideInAPackage("..filter.."))
+                    .or(simpleName("ConnectionHandler"))) //This needs to be accessed because ConnectionHandler creates doFilter()
+            .as("FilterChain access rule")
+            .because("FilterChain should only be accessed by Pipeline, ConnectionHandler")
+            .check(importedClasses);
+    }
+
+
+    /**
+     * The Router should only be accessed by the FilterChain to determine which plugin to execute,
+     * or by App and Pipeline during the system's bootstrapping phase.
+     */
+    @Test
+    void routerRule () {
+        ArchRuleDefinition.classes()
+            .that().haveSimpleName("Router")
+            .should().onlyBeAccessed().byClassesThat(
+                simpleName("FilterChain")
+                    .or(simpleName("FilterChainImpl"))
+                    .or(simpleName("Router"))
+                    .or(simpleName("Pipeline")) //Pipeline injects router
+                    .or(simpleName("App"))) //App Creates router
+            .as("Router access rule")
+            .because("Router should only be accessed by FilterChain, Pipeline, App")
+            .check(importedClasses);
+    }
+
+
+    /**
+     * Plugins must only be instantiated by App at startup and subsequently called by the router or
+     * the execution chain (FilterChainImpl).
+     */
+    @Test
+    void pluginRule () {
+        ArchRuleDefinition.classes()
+            .that().resideInAPackage("..plugin..")
+            .should().onlyBeAccessed().byClassesThat(
+                resideInAPackage("..router..")
+                    .or(resideInAPackage("..plugin.."))
+                    .or(simpleName("App")) //App creates plugin
+                    .or(simpleName("FilterChainImpl"))) //FilterChainImpl calls the plugin after the router has decided which one to run.
+            .as("Plugin access rule")
+            .because("Plugins should only be managed by the Router, App, FilterChainImpl")
+            .check(importedClasses);
+    }
+
+    /**
+     * The HttpResponseWriter is the final step in the request lifecycle, responsible for delivering the response to the client.
+     * This rule ensures that only the ConnectionHandler accesses it, guaranteeing controlled delivery and architectural integrity.
+     */
+    @Test
+    void httpResponseWriterAccessRule() {
+        ArchRuleDefinition.classes()
+            .that().haveSimpleName("HttpResponseWriter")
+            .should().onlyBeAccessed().byClassesThat(
+                simpleName("ConnectionHandler")
+                    .or(simpleName("HttpResponseWriter")))
+            .as("HttpResponseWriter access rule")
+            .because("HttpResponseWriter is the final step in the lifecycle and should" +
+                "only be used by ConnectionHandler to ensure controlled delivery")
+            .check(importedClasses);
+    }
+}
+
+