The framework could be installed by using standard HOWTO:
https://github.com/avocado-framework/avocado#installing-with-standard-python-tools
$ sudo dpkg -i avocado_91.0_all.deb
$ avocado run build_test.py -t fast -p quiet=1 -p cross=1
$ avocado run build_test.py -t full -p quiet=1
$ avocado run vm_boot_test.py -t fast -p build_dir="$BUILDDIR" -p time_to_wait=300
$ avocado run vm_boot_test.py -t full -p build_dir="$BUILDDIR" -p time_to_wait=300
There is a tool start_vm.py which is the replacement for the bash script in isar/scripts directory.