It's important for testing purposes to be able to format a file as an FS. For example, I was just helping someone on Q&A site, and I don't have a spare disk to format as an NTFS to test something.

Formatting a file as an FS works with all other mkfs.*es but not with mkfs.ntfs for some reason. For example, truncate -s 200M disk-file && mkfs.ext4 ./disk-file works no problem.

Steps to reproduce

1. truncate -s 200M disk-file
2. mkfs.ntfs ./disk-file

Expected

Command should succeed

Actual

It fails with:

./disk-file is not a block device.
Refusing to make a filesystem here!