CLI add command

[Keraito]

Issue: More CLI enhancements.

What I did

Added an add command to the storybook CLI to add addons to the Storybook project.

How does it work

1. Syntax: storybook add <addon>. This can be either an official storybook addon like knobs or a random npm package. It can also include a tag like knobs@alpha, as long as it works with yarn or npm.
2. Check if it's an official Storybook addon by running yarn info @storybook/addons-<addon> version (or npm equivalent).
   • If not: check if it's an npm package by executing yarn info <addon> version.
     • If not: display error that it's an invalid addon/npm package.
     • If so: proceed to step 3 with isOfficialAddon = false.
   • If so: proceed to step 3 isOfficialAddon = true.
3. Check isOfficialAddon:
   • If it's false: install it as an devDependency by running yarn add -D <addon>*.
   • If it's true: Check the package.json for installed Storybook packages.
     • If any found: take the version of the first** package found and run yarn add -D @storybook/addons-<addon>@<version>.
     • If none found: run yarn add -D @storybook/addons-<addon>.
4. Register the installed addon by read the .storybook/addons.js and put a register statement after the last register occurrence.

*Maybe adjusting the package.json and then running yarn/npm install is a better long term solution?
**Works under the assumption that the user has the same versions for every installed official Storybook package. My plan is to add some checks on this and warn the user about it in the future.

Please tell me what you guys think, both feature and implementation wise!

[Keraito]

I wouldn't really consider this duplicate code of ~18 lines, CodeFactor 😨

[ndelangen]

It's fine

[codecov]

Codecov Report

Merging #4236 into next will increase coverage by 0.04%.
The diff coverage is 38.09%.

@@            Coverage Diff             @@
##             next    #4236      +/-   ##
==========================================
+ Coverage   35.05%   35.09%   +0.04%     
==========================================
  Files         593      594       +1     
  Lines        7348     7408      +60     
  Branches     1000     1016      +16     
==========================================
+ Hits         2576     2600      +24     
- Misses       4259     4290      +31     
- Partials      513      518       +5

Impacted Files	Coverage Δ
lib/cli/bin/generate.js	0% <0%> (ø)	⬆️
lib/cli/lib/add.js	40% <40%> (ø)
lib/cli/lib/has_yarn.js	0% <0%> (ø)	⬆️

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[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!

[Keraito]

Trying to pick things up again from where I left off 😄 @shilman @ndelangen could I get your thoughts/reviews on this PR? Maybe we can also talk on Discord about what we wanted to work on regarding the CLI.

[shilman]

Looks great!

[shilman]

@Keraito Can you resolve the conflicts?

[Keraito]

will do @shilman !

[Keraito]

Should be good now @shilman

[wuweiweiwu]

NICE!

[stale]

Hi everyone! Seems like there hasn't been much going on in this issue lately. If there are still questions, comments, or bugs, please feel free to continue the discussion. Unfortunately, we don't have time to get to every issue. We are always open to contributions so please send us a pull request if you would like to help. Inactive issues will be closed after 30 days. Thanks!