    public function testAddTags () {
        $contact = $this->contacts ('testAnyone');
        $tags = array ('test', 'test2', 'test3');
        $contact->addTags ($tags);
        $contactTags = $contact->getTags (true);
        $this->assertEquals (
            Tags::normalizeTags ($tags), ArrayUtil::sort ($contactTags));
        // disallow duplicates
        $contact->addTags ($tags);
        $contactTags = $contact->getTags (true);
        $this->assertEquals (
            Tags::normalizeTags ($tags), ArrayUtil::sort ($contactTags));
        // disallow duplicates after normalization
        $tags = array ('te,st', 'test2,', '#test3');
        $contact->addTags ($tags);
        $contactTags = $contact->getTags (true);
        $this->assertEquals (
            Tags::normalizeTags ($tags), ArrayUtil::sort ($contactTags));
    }
The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.