Throw a ValidationException when document contains duplicate resources

Author: JaZo

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 
 * Reworded `ValidationException` messages to align them with the wordings used in the specification.
+* `DocumentParser` throws a `ValidationException` when it encounters duplicate resources.
 
 ## [1.0.0-beta.3] - 2019-09-30
 

src/Parsers/DocumentParser.php

@@ -160,6 +160,16 @@ private function getDocument($data): DocumentInterface
         $allItems = Collection::wrap($document->getData())
             ->concat($document->getIncluded());
 
+        $duplicateItems = $allItems->duplicates(
+            function (ItemInterface $item) {
+                return $this->getItemKey($item);
+            }
+        );
+
+        if ($duplicateItems->isNotEmpty()) {
+            throw new ValidationException(sprintf('Resources MUST be unique based on their `type` and `id`, %d duplicate(s) found.', $duplicateItems->count()));
+        }
+
         $this->linkRelationships($allItems);
 
         return $document;
@@ -170,8 +180,7 @@ private function getDocument($data): DocumentInterface
      */
     private function linkRelationships(Collection $items): void
     {
-        // N.B. We reverse the items to make sure the first item in the collection takes precedence
-        $keyedItems = $items->reverse()->keyBy(
+        $keyedItems = $items->keyBy(
             function (ItemInterface $item) {
                 return $this->getItemKey($item);
             }

tests/Parsers/DocumentParserTest.php

@@ -180,6 +180,42 @@ public function provideInvalidIncluded(): array
         ];
     }
 
+    /**
+     * @test
+     */
+    public function it_throws_when_it_finds_duplicate_resources()
+    {
+        $parser = $this->getDocumentParser();
+
+        $this->expectException(ValidationException::class);
+        $this->expectExceptionMessage('Resources MUST be unique based on their `type` and `id`, 1 duplicate(s) found.');
+
+        $parser->parse(
+            json_encode(
+                [
+                    'data' => [
+                        [
+                            'type' => 'master',
+                            'id' => '1',
+                            'attributes' => [
+                                'foo' => 'bar',
+                            ],
+                        ],
+                    ],
+                    'included' => [
+                        [
+                            'type' => 'master',
+                            'id' => '1',
+                            'attributes' => [
+                                'foo' => 'bar',
+                            ],
+                        ],
+                    ],
+                ]
+            )
+        );
+    }
+
     /**
      * @test
      */