how to make a multypart/data request with browserkit client? - symfony

Question

$data = [
'name' => 'Merry Christamas',
'description' => 'Merry Christamas',
'starts_at' => '2018-9-15 12:45:56',
'ends_at' => '2050-9-15 12:45:56',
'priority' => -1,
'coupon_based' => false,
'action' => [
'type' => 'order_fixed_discount',
'configuration' => [
'amount' => 100
]
],
'rules' => [
[
'type'=> 'item_total',
'configuration' => [
'amount' => 2500,
'base_amount' => 100,
]
]
]
];
$multipartStream = new MultipartStream($this->flatten($data)); //use GuzzleHttp\Psr7\MultipartStream;
I use following method to convert the associative array to MultipartStream needs.
protected function flatten(array $array, string $prefix = '', string $suffix = ''): array
{
$result = [];
foreach ($array as $key => $value) {
if (is_array($value)) {
$result = array_merge($result, $this->flatten($value, $prefix . $key . $suffix . '[', ']'));
} else {
if ($value instanceof UploadedFile) {
$result[] = [
'name' => $prefix . $key . $suffix,
'filename' => $value->getClientOriginalName(),
'Mime-Type' => $value->getClientMimeType(),
'contents' => file_get_contents($value->getPathname()),
];
} else {
$result[] = [
'name' => $prefix . $key . $suffix,
'contents' => $value,
];
}
}
}
return $result;
}
then make request with browserkit client
$this->client->request(
'POST',
'/api/admin/promotions',
[],
[],
[
'CONTENT_TYPE' => 'multipart/form-data; boundary=--'.$multipartStream->getBoundary() ,
'HTTP_Authorization'=> "blabla"
],
$multipartStream->getContents()
);
but the request->request->all() is empty, what is the correct way to make a multipart/data request with symfony browserkit client? I have searched a lot , but have no lucky to find an example.