$contentType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
$I->sendGet('/get_file_uri');
$I->seeResponseCodeIsSuccessful();
$I->seeHttpHeader('Content-Type', $contentType);
$I->seeHttpHeader('Content-Disposition');
$I->seeResponseEquals(file_get_contents('path_to_file'));
<cp:lastModifiedBy>Unknown Creator</cp:lastModifiedBy>
<dcterms:created xsi:type="dcterms:W3CDTF">2023-05-11T13:10:33+00:00</dcterms:created>
<dcterms:modified xsi:type="dcterms:W3CDTF">2023-05-11T13:10:33+00:00</dcterms:modified>
<dc:title>Untitled Spreadsheet</dc:title>