Yes, you can do that by using Command substitution:
Test=$(grep 'test: \K(\d+)' $file),$(grep 'test1: \K(\d+)' $file)
The varible=$(..) called Command substitution and it's means nothing more but to run a shell command and store its output to a variable or display back using echo command. For example, display date and time:
echo "Today is $(date)"
and for store it to a variable:
SERVERNAME=$(hostname)
you can concatenate to output:
echo $(hostname),$(date)
the result will be:
hostname,Tue Jan 24 09:56:32 EET 2017