Laravel\Lumen\Testing\Concerns\MakesHttpRequests::json PHP Method

    public function json($method, $uri, array $data = [], array $headers = [])
    {
        $content = json_encode($data);
        $headers = array_merge(['CONTENT_LENGTH' => mb_strlen($content, '8bit'), 'CONTENT_TYPE' => 'application/json', 'Accept' => 'application/json'], $headers);
        $this->call($method, $uri, [], [], [], $this->transformHeadersToServerVars($headers), $content);
        return $this;
    }