# ./tr a '[c*]b'
# ./tr -s abc zy
# ./tr abc zy
tr a '[:not-a-class:]' < /dev/null
tr a '[:digit:]' < /dev/null
tr '[c*]' k < /dev/null
tr a '[=c=]' < /dev/null
tr a '[c*][c*]' < /dev/null
tr -ds abd '[c*]' < /dev/null
tr -c '[:lower:]' '[:upper:]' < /dev/null
tr '[:lower:]' '[:lower:]' < /dev/null
tr '0-9[:lower:]' '[:upper:]' < /dev/null
tr a '' < /dev/null
tr -s '\432' < /dev/null
tr a 'abc\' < /dev/null
tr a '\x' < /dev/null
tr -s < /dev/null

# And make sure tr does the right thing when POSIXLY_... is set.