yarn upgrade should report exactly what it did

[dlong500]

Do you want to request a feature or report a bug?
Feature request: yarn upgrade should report exactly what it did, so if it updated packages it should list those packages with old version and new version info, such as:

   Packages upgraded:
   react 15.3.2 -> 15.5.4

If any nested dependencies are updated those should be displayed as well (after the list of updated direct dependencies). Otherwise it should report "No packages upgraded" if nothing is changed.

It could also be useful to have an option for a log file that keeps a running log of package updates. This might be useful for diagnostics if an issue crops up in a user's codebase and there is a question about what packages might have changed during a certain time period.

What is the current behavior?
No information is reported except for the entire package tree (whether anything changed or not). I would argue that the tree output is not very useful for most people, and could be obtained through other commands if necessary.

[arcanis]

That could be interesting. However, isn't diffing the lockfile enough?

[dlong500]

For projects committing the lockfile then yes, you could get the information out of that assuming you did a git commit every single time the lockfile changes. However, even then I'd argue this would be a useful summary of information to see upon running the upgrade command.

But what about scenarios where the lockfile isn't being tracked (for quick test projects or playgrounds)? If the lockfile isn't tracked then you lose all previous information once an upgrade is run and thus can't do a diff. And even if you are committing the lockfile, what if you run multiple yarn upgrade commands without doing a git commit? You'd then lose the intermediate changes and only be able to diff with the latest committed lockfile.

[Anahkiasen]

This is also true for global dependencies, every time you run yarn global upgrade it spits out all the global packages and their dependencies which a) is very verbose b) doesn't provide much value. I 👍 the need for a more selective output that shows what was actually updated instead.

[arcanis]

I can see the point. Feel free to open a PR with a prototype!

[rally25rs]

@bestander triage; label: [discussion | new feature]