GET /hello.html
body contains <!DOCTYPE html>
code == 200
code != 404
header content-type == text/html; charset=utf-8
body ~ hello, +world
body != hello, world
body ==
	<!DOCTYPE html>
	hello, world
body !~ \A\z

HEAD https://example.com/hello.html
code == 200
body !~ .

# check failed test
GET /hello.html
hint header content-type = "text/html; charset=utf-8", want "text/html"
header content-type == text/html

# check failed test
GET /hello.html
hint body matches `.` (but should not)
body !~ .

# check failed test
GET /hello.html
hint body contains `hello` (but should not)
body !contains hello