Automatically add newline at the end of file

[jaladh-singhal]

Is your feature request related to a problem? Please describe.
Black doesn't enter newline at EOF on its own if there is not any

Describe the solution you'd like
It should auto insert new line or at least provide a configuration option that does so

Additional context
I think it's recommended somewhere in PEP8, besides several other code formatters does it

[JelleZijlstra]

I believe we already do this. Could you give an example where we don't?

[ichard26]

Maybe VS Code integration -> #1662?

[rcalfredson]

I stumbled across a corner case where the newline doesn't appear: seemingly, when the length of the last line equals the limit (i.e., the default of 88). Here is a tiny script where I found it:

import numpy as np

PATCH_UBOUND = 160
patch = np.zeros((PATCH_UBOUND, PATCH_UBOUND, 1))
for _ in range(4):
    patch[np.random.randint(0, PATCH_UBOUND), np.random.randint(0, PATCH_UBOUND), :] = 1

In all other cases, the newline got added in my experience with Black.

[ichard26]

We haven't been able to find a consistent working reproduction so closing (even the one above doesn't work for me).