Remove responsibility for managing state from [ButtonGroup]

[yujonglee]

Description

1. given and context are awesome libraries to write readable test codes. Although I use only context here, they usually work together. So I add both to commit.
2. [ButtonGroup] doesn't need to be responsible for managing selected option. It makes testing hard(in general), and reduces reusability and flexibility of component.

Related Issues

#52

Tests

I update test code first. Then modify [ButtonGroup] to fulfill tests.
So changes in test code represents what I did in [ButtonGroup].

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• Run yarn test or yarn test -u if you need to update snapshot.
• Run yarn lint
• I am willing to follow-up on review comments in a timely manner.

[codecov]

Codecov Report

Merging #56 (66da1a7) into master (30d9491) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #56      +/-   ##
==========================================
+ Coverage   93.91%   93.93%   +0.02%     
==========================================
  Files          21       21              
  Lines         542      544       +2     
  Branches      231      235       +4     
==========================================
+ Hits          509      511       +2     
  Misses         33       33              

[hyochan]

@yujong-lee Yeah jest-plugin-context looks awesome. But I am afraid that this isn't been maintained for 3 years 🤔

[hyochan]

Also we need to add @types/jest-plugin-context for typescript

[yujonglee]

Ok. I rename variable and install @types/jest-plugin-context.

There's few things I want to share.

1. context is just aliases of describe.
   See source code. So In this case, I think the fact that this library is not maintained for 3 years doesn't really matters.

2. But, given2 is more complex library, and it's not maintaining these days too.
   So I find two alternative library. givens and bdd-lazy-var.

givens : similar interface with given2. Which is familiar to me and other RSpec-background-developers. Auther said it has advantages over given2and bdd-lazy-var. But I haven't used/heard of it so it needs some testing. It is also maintained by single author.

bdd-lazy-var : different interface with given2. Has more feature than given2, but they are not crucial.(in my opinion.) Good documentation. Many contributors. Updated(except bot) less than 1 year. It has built-in context aliases.

I'm not confident to choose one now. (jest-plugin-context + given2 or givens / bdd-lazy-var)
So what I suggest is add this talk to discussion. remove given2 from this PR, and choose among these options when it is needed. (It will be needed soon).

[hyochan]

Looks like the props here is not changed yet selectedIndex

[yujonglee]

Sorry for that.
This happens due to insufficient test that didn't caught my mistake.
I updated test codes to test default value of selectedIndex, check test fails, and fix mistake to pass it.

[hyochan]

Ok. I rename variable and install @types/jest-plugin-context.

There's few thing I want to share.

1. context is just aliases of describe.
   See source code. So In this case, I think the fact that this library is not maintained for 3 years doesn't really matters.
2. But, given2 is more complex library, and it's not maintaining these days too.
   So I find two alternative library. givens and bdd-lazy-var.

givens : similar interface with given2. Which is familiar to me and other RSpec-background-developers. Auther said it has advantages over given2and bdd-lazy-var. But I haven't used/heard of it so it needs some testing. It is also maintained by single author.

bdd-lazy-var : different interface with given2. Has more feature than given2, but they are not crucial.(in my opinion.) Good documentation. Many contributors. Updated(except bot) less than 1 year. It has built-in context aliases.

I'm not confident to choose one now. (jest-plugin-context + given2 or givens / bdd-lazy-var)
So what I suggest is add this talk to discussion. remove given2 from this PR, and choose among these options when it is needed. (It will be needed soon).

It looks like a great discussion to start! Could you kindly open up a discussion?

[yujonglee]

No problem!

[hyochan]

LGTM!