From e5947540da77f0c22db8ed7eea5d9f5dc3efd401 Mon Sep 17 00:00:00 2001
From: mnhock <martin.hock.de@gmail.com>
Date: Wed, 12 Jun 2024 17:20:08 +0200
Subject: [PATCH] Provide a New Java Rule checking if a class is not used

Closes gh-19
---
 docs/USERGUIDE.md                             | 22 +++++++++++++++++++
 .../enofex/taikai/java/JavaConfigurer.java    | 19 ++++++++++++++++
 .../com/enofex/taikai/ArchitectureTest.java   |  6 +++++
 src/test/java/com/enofex/taikai/Usage.java    |  7 ++++++
 4 files changed, 54 insertions(+)

diff --git a/docs/USERGUIDE.md b/docs/USERGUIDE.md
index e129b61..182c094 100644
--- a/docs/USERGUIDE.md
+++ b/docs/USERGUIDE.md
@@ -123,6 +123,28 @@ Taikai.builder()
     .check();
 ```
 
+- **No Usage of Specific Classes**: Ensure that certain classes are not used in your codebase.
+
+```java
+Taikai.builder()
+    .namespace("com.company.yourproject")
+    .java(java -> java
+        .noUsageOf("com.example.UnwantedClass"))
+    .build()
+    .check();
+```
+
+- **No Usage of Specific Classes by Class Reference**: Ensure that certain classes are not used in your codebase by directly referencing the class.
+
+```java
+Taikai.builder()
+    .namespace("com.company.yourproject")
+    .java(java -> java
+        .noUsageOf(UnwantedClass.class))
+    .build()
+    .check();
+```
+
 #### Spring Configuration
 
 Spring configuration involves defining constraints specific to Spring Framework usage.
diff --git a/src/main/java/com/enofex/taikai/java/JavaConfigurer.java b/src/main/java/com/enofex/taikai/java/JavaConfigurer.java
index 119560e..6a6a485 100644
--- a/src/main/java/com/enofex/taikai/java/JavaConfigurer.java
+++ b/src/main/java/com/enofex/taikai/java/JavaConfigurer.java
@@ -9,6 +9,7 @@
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.classes;
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.fields;
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.methods;
+import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.noClasses;
 
 import com.enofex.taikai.TaikaiRule;
 import com.enofex.taikai.TaikaiRule.Configuration;
@@ -76,6 +77,24 @@ public JavaConfigurer fieldsShouldNotBePublic(Configuration configuration) {
     return addRule(TaikaiRule.of(fields().should(notBePublic()), configuration));
   }
 
+  public JavaConfigurer noUsageOf(Class clazz) {
+    return noUsageOf(clazz, null);
+  }
+
+  public JavaConfigurer noUsageOf(String typeName) {
+    return noUsageOf(typeName, null);
+  }
+
+  public JavaConfigurer noUsageOf(String typeName, Configuration configuration) {
+    return addRule(TaikaiRule.of(noClasses()
+        .should().dependOnClassesThat().areAssignableTo(typeName), configuration));
+  }
+
+  public JavaConfigurer noUsageOf(Class clazz, Configuration configuration) {
+    return addRule(TaikaiRule.of(noClasses().should().dependOnClassesThat().areAssignableTo(clazz),
+        configuration));
+  }
+
   @Override
   public void disable() {
     disable(ImportsConfigurer.class);
diff --git a/src/test/java/com/enofex/taikai/ArchitectureTest.java b/src/test/java/com/enofex/taikai/ArchitectureTest.java
index e8cb648..bfc3a52 100644
--- a/src/test/java/com/enofex/taikai/ArchitectureTest.java
+++ b/src/test/java/com/enofex/taikai/ArchitectureTest.java
@@ -1,5 +1,8 @@
 package com.enofex.taikai;
 
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
 import org.junit.jupiter.api.Test;
 
 class ArchitectureTest {
@@ -18,6 +21,9 @@ void shouldFulfilConstrains() {
             .methodsShouldNotThrowGenericException()
             .utilityClassesShouldBeFinalAndHavePrivateConstructor()
             .fieldsShouldNotBePublic()
+            .noUsageOf(Date.class)
+            .noUsageOf(Calendar.class)
+            .noUsageOf("java.text.SimpleDateFormat")
             .imports(imports -> imports
                 .shouldHaveNoCycles()
                 .shouldNotImport("..shaded..")
diff --git a/src/test/java/com/enofex/taikai/Usage.java b/src/test/java/com/enofex/taikai/Usage.java
index 4adeb89..0d32b8e 100644
--- a/src/test/java/com/enofex/taikai/Usage.java
+++ b/src/test/java/com/enofex/taikai/Usage.java
@@ -1,5 +1,9 @@
 package com.enofex.taikai;
 
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
+
 class Usage {
 
   public static void main(String[] args) {
@@ -35,6 +39,9 @@ public static void main(String[] args) {
             .classesShouldImplementHashCodeAndEquals()
             .methodsShouldNotThrowGenericException()
             .utilityClassesShouldBeFinalAndHavePrivateConstructor()
+            .noUsageOf(Date.class)
+            .noUsageOf(Calendar.class)
+            .noUsageOf("java.text.SimpleDateFormat")
             .imports(imports -> imports
                 .shouldHaveNoCycles()
                 .shouldNotImport("..shaded..")