prettier/tests/css_atrule/charset.css

@charset "UTF-8";
@charset "iso-8859-15";
@charset 'iso-8859-15'; /* Invalid, wrong quoting style used */
@charset  "UTF-8"; /* Invalid, more than one space */
@charset "UTF-8"; /* Invalid, there is a character (a space) before the at-rule */
@charset UTF-8; /* Invalid, without ' or ", the charset is not a CSS <string> */