Ignore case sensitive in Case Switch

Shell Programming and Scripting
1

In a Case switch, how to ignore case sensitive in the test:

e.g.

case "$field" in
"TEST) action1;;
*) action2;;
esac

How to go in action1 in case of $field = TEST , or Test , or test or .... without enumerating all possibilities...

Thanks, Annick.

2 
case "$field" in
"[tT][eE][sS][tT]) action1;;
*) action2;;
esac