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Selenide, надо чекбокс отметить
Пробовал так
//VAT - on
//$("[data-test-id='registrationDealerForm_vat_payer']").setSelected(true);
//$("[data-test-id='registrationDealerForm_vat_payer']").setSelected(true);
//$("[id='vat_payer47']").setSelected(true);
//$("[name='vat_payer']").click();
//$(By.className("vac-player")).click();
//$("input[type='checkbox'][name='vat_payer']").click();
$("input[type='checkbox'][name='vat_payer']").setSelected(true);
id='vat_payer47' - не вариант, так как цифра меняется после каждого рефреша
[attribute~=value] [title~=flower] Selects all elements with a title attribute containing the word "flower"
[attribute|=value] [lang|=en] Selects all elements with a lang attribute value starting with "en"
[attribute^=value] a[href^="https"] Selects every <a> element whose href attribute value begins with "https"
[attribute$=value] a[href$=".pdf"] Selects every <a> element whose href attribute value ends with ".pdf"
[attribute*=value] a[href*="w3schools"] Selects every <a> element whose href attribute value contains the substring "w3schools"
Если цифра меняется, то можно [id^="vat_payer"] или [id*="vat_payer"] попробовать.