avoid error "storyshots is intended only to be used with storybook" f…

[osdevisnot]

…or transitive dependency on @storybook/react

Issue: When @storybook/react is not a direct dependency in package.json - the storyshots fails to execute tests with error "storyshots is intended only to be used with storybook". This is ok in normal circumstances, but limits wrapping "@storybook" into a higher order package.

For example: a project depends on a higher order package (maybe CLI tool). this higher order package brings in both @storybook/react and @storybook/addon-storyshots with appropriate config. The storyshots will throw above mentioned error.

What I did

Add a fallback check to see if package.json exists before bailing out on dependency being available.

How to test

Tested it by using this package in my project.

[codecov]

Codecov Report

Merging #1441 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1441   +/-   ##
=======================================
  Coverage   21.32%   21.32%           
=======================================
  Files         257      257           
  Lines        5739     5739           
  Branches      686      679    -7     
=======================================
  Hits         1224     1224           
- Misses       3981     3993   +12     
+ Partials      534      522   -12

Impacted Files	Coverage Δ
addons/storyshots/src/index.js	0% <ø> (ø)	⬆️
lib/ui/src/modules/ui/containers/left_panel.js	25.71% <0%> (ø)	⬆️
.../src/manager/containers/CommentsPanel/dataStore.js	34.97% <0%> (ø)	⬆️
addons/info/src/components/Node.js	39.43% <0%> (ø)	⬆️
...es__/update-addon-info/update-addon-info.output.js	0% <0%> (ø)	⬆️
addons/knobs/src/components/types/Object.js	5.81% <0%> (ø)	⬆️
app/react/src/client/preview/error_display.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/components/layout/usplit.js	38.7% <0%> (ø)	⬆️
.../ui/src/modules/ui/components/left_panel/header.js	29.62% <0%> (ø)	⬆️
addons/knobs/src/components/PropForm.js	8.51% <0%> (ø)	⬆️
... and 15 more

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[shilman]

@osdevisnot thanks for your contribution! One thing --
how do I test it on my machine?

[osdevisnot]

Setup storyshots as you normally would, and then remove @storybook/react dependency from package.json but leave the installed version in node_modules.

Without this PR, you should be able to see above error.
@shilman

[shilman]

@osdevisnot OK great, thanks! I'll give it a whirl. FYI, "@storybook/react" in your initial comment was not escaped, so it just showed up as "" on github. I went through and fixed it for you, but for future reference ... 😉

[osdevisnot]

Aw, I feel stupid.. will be more careful with markdown :( thanks for correcting it.

[tmeasday]

I guess that makes sense!

[shilman]

@ndelangen looks like there are some CircleCI config issues when the pull is coming from a fork of our repo?

[ndelangen]

Sorry for the delay, LGTM!