Remove duplicate $ref in allOf

src/Processors/AugmentRefs.php

@@ -18,12 +18,13 @@ public function __invoke(Analysis $analysis)
     {
         $this->resolveAllOfRefs($analysis);
         $this->resolveFQCNRefs($analysis);
+        $this->removeDuplicateRefs($analysis);
     }
 
     /**
      * Update refs broken due to `allOf` augmenting.
      */
-    protected function resolveAllOfRefs(Analysis $analysis)
+    protected function resolveAllOfRefs(Analysis $analysis): void
     {
         /** @var OA\Schema[] $schemas */
         $schemas = $analysis->getAnnotationsOfType(OA\Schema::class);
@@ -55,7 +56,7 @@ protected function resolveAllOfRefs(Analysis $analysis)
         }
     }
 
-    protected function resolveFQCNRefs(Analysis $analysis)
+    protected function resolveFQCNRefs(Analysis $analysis): void
     {
         /** @var OA\AbstractAnnotation[] $annotations */
         $annotations = $analysis->getAnnotationsOfType([OA\Examples::class, OA\Header::class, OA\Link::class, OA\Parameter::class, OA\PathItem::class, OA\RequestBody::class, OA\Response::class, OA\Schema::class, OA\SecurityScheme::class]);
@@ -69,4 +70,31 @@ protected function resolveFQCNRefs(Analysis $analysis)
             }
         }
     }
+
+    protected function removeDuplicateRefs(Analysis $analysis): void
+    {
+        /** @var OA\Schema[] $schemas */
+        $schemas = $analysis->getAnnotationsOfType(OA\Schema::class);
+
+        foreach ($schemas as $schema) {
+            if (!Generator::isDefault($schema->allOf)) {
+                $refs = [];
+                $dupes = [];
+                foreach ($schema->allOf as $ii => $allOfSchema) {
+                    if (!Generator::isDefault($allOfSchema->ref)) {
+                        if (in_array($allOfSchema->ref, $refs)) {
+                            $dupes[] = $allOfSchema->ref;
+                            $analysis->annotations->detach($allOfSchema);
+                            unset($schema->allOf[$ii]);
+                            continue;
+                        }
+                        $refs[] = $allOfSchema->ref;
+                    }
+                }
+                if ($dupes) {
+                    $schema->allOf = array_values($schema->allOf);
+                }
+            }
+        }
+    }
 }

tests/Fixtures/Scratch/DuplicateRef.php

@@ -0,0 +1,41 @@
+<?php declare(strict_types=1);
+
+/**
+ * @license Apache 2.0
+ */
+
+namespace OpenApi\Tests\Fixtures\Scratch;
+
+use OpenApi\Attributes as OAT;
+
+#[OAT\Info(title: 'DuplicateRef', version: '1.0')]
+#[OAT\Get(
+    path: '/api/endpoint',
+    description: 'An endpoint',
+    responses: [new OAT\Response(response: 200, description: 'OK')]
+)]
+class DuplicateRefEndpoint
+{
+}
+
+#[OAT\Schema(
+    schema: 'abstract-user',
+    properties: [
+        new OAT\Property(property: 'name', type: 'string'),
+        new OAT\Property(property: 'email', type: 'string'),
+    ]
+)]
+class AbstractUser
+{
+}
+
+#[OAT\Schema(
+    schema: 'create-user',
+    allOf: [
+        new OAT\Schema(ref: '#/components/schemas/abstract-user'),
+        new OAT\Schema(required: ['name', 'email']),
+    ]
+)]
+class CreateUser extends AbstractUser
+{
+}

tests/Fixtures/Scratch/DuplicateRef.yaml

@@ -0,0 +1,28 @@
+openapi: 3.0.0
+info:
+  title: DuplicateRef
+  version: '1.0'
+paths:
+  /api/endpoint:
+    get:
+      description: 'An endpoint'
+      responses:
+        '200':
+          description: OK
+components:
+  schemas:
+    abstract-user:
+      properties:
+        name:
+          type: string
+        email:
+          type: string
+      type: object
+    create-user:
+      allOf:
+        -
+          $ref: '#/components/schemas/abstract-user'
+        -
+          required:
+            - name
+            - email

tests/Processors/ExpandClassesTest.php

@@ -108,14 +108,14 @@ public function testExpandClassesWithAllOf(): void
 
         /** @var OA\Schema[] $schemas */
         $schemas = $analysis->getAnnotationsOfType(OA\Schema::class, true);
-        $this->assertCount(5, $schemas);
+        $this->assertCount(4, $schemas);
 
         $extendedSchema = $schemas[0];
         $this->assertSame('ExtendedModel', $extendedSchema->schema);
         $this->assertSame(Generator::UNDEFINED, $extendedSchema->properties);
 
         $this->assertArrayHasKey(0, $extendedSchema->allOf);
-        $this->assertEquals($extendedSchema->allOf[2]->properties[0]->property, 'extendedProperty');
+        $this->assertEquals($extendedSchema->allOf[1]->properties[0]->property, 'extendedProperty');
 
         $includeSchemaWithRef = $schemas[1];
         $this->assertSame(Generator::UNDEFINED, $includeSchemaWithRef->properties);