Fix types for Oneof

[skyline0705]

In code, the typeof Oneof is new Rule, someone (like me) may use code like

const rule = webpackConfig.module.rule(lang).oneOf(type);
rule.uses.delete('something')

And I check the typing file, Type Oneof is not extends from Rule：https://github.com/neutrinojs/webpack-chain/blob/master/src/Rule.js#L40

[edmorley]

Hi! Thank you for the PR.

The tests are currently failing with:

$ tsc -p ./types/test/tsconfig.json
types/test/webpack-chain-tests.ts:301:8 - error TS2339: Property 'oneOfs' does not exist on type 'Module'.
301       .oneOfs
           ~~~~~~

Also, if there is a bug (that this PR is hoping to fix), it would be good to add a test for the case that was not previously working, to:
https://github.com/neutrinojs/webpack-chain/blob/master/types/test/webpack-chain-tests.ts

[skyline0705]

@edmorley Thanks~~
I have add some test about this case, I don't know is this the best way to fix this bug. I have check the Code at above, the type 'OneOf' first must to be a 'Rule', but the typing file use 'ChainMap', which lose the properties at 'Rule'

[edmorley]

@fimars @imyelo @Jetsly @loveky @bolasblack @opl-

Hi! Sorry for the mass @ mention - but you've all kindly contributed to the webpack-chain type definitions in the past, so I wondered if you'd be able to take a look at this PR? I'm not very familiar with TypeScript best practices, so not in the position to know if this is the correct fix for the issue mentioned above.

Thanks :-)

[loveky]

Created PR #218 to fix this type issue.

@skyline0705 also added your new test case in #218. Please help check if that solves your problem.

[skyline0705]

Look good！I have tried to make oneOf as a Rule<Rule>, but it has some errors because I did not make Rule implements from Orderable

Thanks very much！ @loveky

[edmorley]

Thank you everyone!