How can i generate random number of files with random string and random files sizes?

For example to create 100 text files each text file with random string/s and each text file to be random size for example between 1-100MB or 1-10GB so i will have on the hard disk some files size 10GB some 1GB or if i select 1-100Mb so some files 1MB and some 100MB the files sizes should be random too.

So on the hard disk i will have 100 text files each one in another size with random string/s