Do not add the same tag multiple times

Author: Toflar

src/ResponseTagger.php

@@ -123,7 +123,7 @@ public function addTags(array $tags)
             throw new InvalidTagException('Empty tags are not allowed');
         }
 
-        $this->tags = array_merge($this->tags, $filtered);
+        $this->tags = array_unique(array_merge($this->tags, $filtered));
 
         return $this;
     }

tests/Unit/ResponseTaggerTest.php

@@ -132,4 +132,15 @@ public function testNonStrictEmptyTag()
         $this->assertTrue($tagHandler->hasTags());
         $this->assertEquals('post-1', $tagHandler->getTagsHeaderValue());
     }
+
+    public function testUniqueTags()
+    {
+        $headerFormatter = new CommaSeparatedTagHeaderFormatter('FOS-Tags');
+
+        $tagHandler = new ResponseTagger(['header_formatter' => $headerFormatter, 'strict' => true]);
+        $tagHandler->addTags(['post-1', 'post-2', 'post-1']);
+        $this->assertTrue($tagHandler->hasTags());
+
+        $this->assertEquals('post-1,post-2', $tagHandler->getTagsHeaderValue());
+    }
 }