[theme] Correct augmentColor TypeScript definition

[sveyret]

• I have followed (at least) the PR section of the contributing guide.

[eps1lon]

Bonus points if you add some tests for the declarations.

You can simply create a file named ´createPalette.spec.tsnext to the declarations and write some usage statements in there (e.g. examples from the unit tests) and annotate those statements with// $ExpectError` where you think ts should report at compile time.

e.g. packages/material-ui/TextField/TextField.spec.tsx is such a test for type declarations.

[oliviertassinari]

💯 for adding new TypeScript and unit tests.

[sveyret]

Actually, shade parameters are useless with a SimplePaletteColorOption which does not include color variations… So I made an override, at last, as @eps1lon suggested. I also added Typescript tests.

updated

[sveyret]

I have another suggestion. As you defined the type PartialColor, and as it seems this partial color should at least have a [500] entry, shouldn't we write:

export type ColorPartial = Partial<Color> & {500: string};

This would prevent from giving an empty object {} as a color.

Edit: Actually, this may not be a good idea, because if the color needs to have at least one entry, the one defined in main shade, it does not need to be 500.