Add files with progress callback - called 58 times?

[alanshaw]

https://github.com/ipfs/interface-ipfs-core/blob/master/src/files.js#L115

Just wondering where there 58 comes from and what it's testing? I think it might be a brittle check as it's probably determined by data storage/transfer in much deeper dependencies that these tests have no control over.

It might work for now (and on the systems the tests are run on) but break later. I think it's enough to check that the progress function was called at least once and that the reported progress bytes is equal to the total bytes uploaded.

Would you accept a PR for this change?

[victorb]

Indeed testing how many times the handler is called is testing the internal implementation rather than expecting correct output. I would happily accept a fix for this.