Black formatting leaves an extra line at the end of the file

Environment data

• VS Code version: 1.23.1
• Extension version (available under the Extensions sidebar): 2018.5.0
• OS and version: macOs High Sierra
• Python version (& distribution if applicable, e.g. Anaconda): CPython 3.6.5
• Type of virtual environment used (N/A | venv | virtualenv | conda | …): venv
• Relevant/affected Python packages and their versions: black-18.6b1

Actual behavior

Formatting using black leaves two empty lines at the end of the file, if the file has more than 1 empty line already.

Expected behavior

Formatting should leave just one line, and this is what happens when I run black manually from the terminal.

Steps to reproduce:

1. Open Python file
2. Insert 10 empty lines at the end
3. Activate “Format document” with black set as the formatter

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

##########Linting Output - flake8##########
20,1,W,W391:blank line at end of file

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help)

[ashleybartlett]

I have just run into this issue. From the cli, black will change the file correctly. When saving, It will format the rest of the document, and leaves the extra blank line/ I even see the same flake8 picking this up as a formatting error.

If I have no blank lines, it adds one, if I have multiple it removes all but 2. I tried this out with a new file and found the same result.

This caught me out, as our CI pipeline runs black --check and fails. Which it did.

[roberthubblehq]

{ "files.trimFinalNewlines": true } in settings.json seems to fix this.