curl --request PATCH \
  --url https://api.lemlist.com/api/sequences/{sequenceId}/steps/{stepId}/ab-test \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "subject": "New subject B",
  "message": "<div>New body B</div>"
}
'

import requests

url = "https://api.lemlist.com/api/sequences/{sequenceId}/steps/{stepId}/ab-test"

payload = {
    "subject": "New subject B",
    "message": "<div>New body B</div>"
}
headers = {
    "Authorization": "Basic <encoded-value>",
    "Content-Type": "application/json"
}

response = requests.patch(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'PATCH',
  headers: {Authorization: 'Basic <encoded-value>', 'Content-Type': 'application/json'},
  body: JSON.stringify({subject: 'New subject B', message: '<div>New body B</div>'})
};

fetch('https://api.lemlist.com/api/sequences/{sequenceId}/steps/{stepId}/ab-test', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

require 'uri'
require 'net/http'

url = URI("https://api.lemlist.com/api/sequences/{sequenceId}/steps/{stepId}/ab-test")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Patch.new(url)
request["Authorization"] = 'Basic <encoded-value>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"subject\": \"New subject B\",\n  \"message\": \"<div>New body B</div>\"\n}"

response = http.request(request)
puts response.read_body

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.lemlist.com/api/sequences/{sequenceId}/steps/{stepId}/ab-test",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PATCH",
  CURLOPT_POSTFIELDS => json_encode([
    'subject' => 'New subject B',
    'message' => '<div>New body B</div>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Basic <encoded-value>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

{
  "stepId": "stp_V0JHmSpWiO0rxHUkz",
  "abTest": true,
  "emailTemplateBId": "etp_9aZ2k1QwErTyUiOp3",
  "subject": "Quick question, {{firstName}}",
  "message": "<div>Hi {{firstName}}, ...</div>"
}

{
  "error": "The premium invitation note must not exceed 300 characters",
  "code": "SEQUENCE_AB_ALT_MESSAGE_TOO_LONG"
}

The authentication you supplied is incorrect

route is available starting emailPro plan

{
  "error": "No A/B test variant on this step",
  "code": "SEQUENCE_AB_NO_VARIANT"
}

{
  "error": "Bad method"
}