You can do this with “cat” and a here-document.
cat <<EOF > test.txt
some text
EOF
One reason for doing this would be to avoid any possibility of a password being visible in the output of ps. However, in bash and most modern shells, “echo” is a built-in command and it won’t show up in ps output, so using something like this is safe (ignoring any issues with storing passwords in files, of course):
echo "$password" > test.txt