Before busboy v1, the fileSize limit would be the number of bytes that are allowed. Now in v1, it's changed to being the number of bytes that first exceeds the limit.

Basically, if in the busboy limits you set fileSize: 1 and a text file contains only 1 character, it used to be allowed without truncating the file contents. Now with v1 in the same situation the limit event is emitted in the file stream and truncation occurs.

I think the new behavior is incorrect, and the old behavior should be restored in a bug fix patch release. I noticed this issue because tests started failing in graphql-upload when attempting to update the busboy dependency.