Fix appliesTo() logic for trait rules - traits can use traits

Following the pattern from PR #561, fix the appliesTo() logic:
- Traits CAN use other traits in PHP
- Only interfaces cannot use traits
- Both HaveTrait and NotHaveTrait now apply to traits (consistent logic)

Changes:
- Update appliesTo() to only exclude interfaces
- Update evaluate() to only skip interfaces
- Update tests to verify traits are properly evaluated
- Add tests for traits using/not using other traits

This ensures the rules work correctly for all PHP class types.

Author: claude

src/Expression/ForClasses/HaveTrait.php

@@ -27,12 +27,12 @@ public function describe(ClassDescription $theClass, string $because): Descripti
 
     public function appliesTo(ClassDescription $theClass): bool
     {
-        return !($theClass->isInterface() || $theClass->isTrait());
+        return !$theClass->isInterface();
     }
 
     public function evaluate(ClassDescription $theClass, Violations $violations, string $because): void
     {
-        if ($theClass->isInterface() || $theClass->isTrait()) {
+        if ($theClass->isInterface()) {
             return;
         }
 

src/Expression/ForClasses/NotHaveTrait.php

@@ -29,12 +29,12 @@ public function describe(ClassDescription $theClass, string $because): Descripti
 
     public function appliesTo(ClassDescription $theClass): bool
     {
-        return !($theClass->isInterface() || $theClass->isTrait());
+        return !$theClass->isInterface();
     }
 
     public function evaluate(ClassDescription $theClass, Violations $violations, string $because): void
     {
-        if ($theClass->isInterface() || $theClass->isTrait()) {
+        if ($theClass->isInterface()) {
             return;
         }
 

tests/Unit/Expressions/ForClasses/HaveTraitTest.php

@@ -86,7 +86,7 @@ public function test_it_should_return_no_violation_if_is_an_interface(): void
         self::assertEquals(0, $violations->count());
     }
 
-    public function test_it_should_return_no_violation_if_is_a_trait(): void
+    public function test_it_should_return_violation_if_trait_does_not_use_required_trait(): void
     {
         $expression = new HaveTrait('MyTrait');
 
@@ -100,6 +100,24 @@ public function test_it_should_return_no_violation_if_is_a_trait(): void
         $violations = new Violations();
         $expression->evaluate($classDescription, $violations, $because);
 
+        self::assertEquals(1, $violations->count());
+    }
+
+    public function test_it_should_return_no_violation_if_trait_uses_required_trait(): void
+    {
+        $expression = new HaveTrait('MyTrait');
+
+        $classDescription = (new ClassDescriptionBuilder())
+            ->setFilePath('src/Foo.php')
+            ->setClassName('HappyIsland')
+            ->setTrait(true)
+            ->addTrait('MyTrait', 1)
+            ->build();
+
+        $because = 'we want to add this rule for our software';
+        $violations = new Violations();
+        $expression->evaluate($classDescription, $violations, $because);
+
         self::assertEquals(0, $violations->count());
     }
 
@@ -128,7 +146,7 @@ public function test_applies_to_should_return_false_for_interfaces(): void
         self::assertFalse($expression->appliesTo($classDescription));
     }
 
-    public function test_applies_to_should_return_false_for_traits(): void
+    public function test_applies_to_should_return_true_for_traits(): void
     {
         $expression = new HaveTrait('MyTrait');
 
@@ -138,6 +156,6 @@ public function test_applies_to_should_return_false_for_traits(): void
             ->setTrait(true)
             ->build();
 
-        self::assertFalse($expression->appliesTo($classDescription));
+        self::assertTrue($expression->appliesTo($classDescription));
     }
 }

tests/Unit/Expressions/ForClasses/NotHaveTraitTest.php

@@ -84,7 +84,7 @@ public function test_it_should_return_no_violation_if_is_an_interface(): void
         self::assertEquals(0, $violations->count());
     }
 
-    public function test_it_should_return_no_violation_if_is_a_trait(): void
+    public function test_it_should_return_no_violation_if_trait_does_not_use_prohibited_trait(): void
     {
         $traitConstraint = new NotHaveTrait('MyTrait');
 
@@ -101,6 +101,24 @@ public function test_it_should_return_no_violation_if_is_a_trait(): void
         self::assertEquals(0, $violations->count());
     }
 
+    public function test_it_should_return_violation_if_trait_uses_prohibited_trait(): void
+    {
+        $traitConstraint = new NotHaveTrait('MyTrait');
+
+        $classDescription = (new ClassDescriptionBuilder())
+            ->setFilePath('src/Foo.php')
+            ->setClassName('HappyIsland')
+            ->setTrait(true)
+            ->addTrait('MyTrait', 1)
+            ->build();
+
+        $because = 'we want to add this rule for our software';
+        $violations = new Violations();
+        $traitConstraint->evaluate($classDescription, $violations, $because);
+
+        self::assertEquals(1, $violations->count());
+    }
+
     public function test_applies_to_should_return_true_for_regular_classes(): void
     {
         $traitConstraint = new NotHaveTrait('MyTrait');
@@ -126,7 +144,7 @@ public function test_applies_to_should_return_false_for_interfaces(): void
         self::assertFalse($traitConstraint->appliesTo($classDescription));
     }
 
-    public function test_applies_to_should_return_false_for_traits(): void
+    public function test_applies_to_should_return_true_for_traits(): void
     {
         $traitConstraint = new NotHaveTrait('MyTrait');
 
@@ -136,6 +154,6 @@ public function test_applies_to_should_return_false_for_traits(): void
             ->setTrait(true)
             ->build();
 
-        self::assertFalse($traitConstraint->appliesTo($classDescription));
+        self::assertTrue($traitConstraint->appliesTo($classDescription));
     }
 }