Suggestion: addon-knobs select() with TypeScript enum

[ChristianOezelt]

Is your feature request related to a problem? Please describe.
I'd like if (none const) enums are working out of the box with select(...) knobs, as this is "just" a typing issue.

Here is an example of what I'd like to do:

index.tsx

export enum ButtonVariant {
    primary = 'primary',
    secondary = 'secondary'
}

export const Button: React.FC<{ variant: ButtonVariant }> = ({ variant }) => /* ... */;

index.story.tsx

storiesOf('Button', module)
    .add('variants', () => <Button variant={ select('variant', ButtonVariant, ButtonVariant.primary) }/>)

Describe the solution you'd like
The fix I currently use is a custom module declaration in my project.
I suppose the additional type could be added as an overload of the select() function

/**
 * the import is here to make the file a module
 * else it would replace the typedefs, instead of extending them
 * which leads to missing types for everything, but select with enums
 */
import '@storybook/addon-knobs';

declare module '@storybook/addon-knobs' {
    /**
     * @typeparam EnumT any none const enum, e.g ButtonVariant
     * @typeparam ResultT one (and any) of the enum values, e.g ButtonVariant.Primary
     *
     * @example
     * enum ButtonVariant {
     *   Primary = 'primary',
     *   Secondary = 'secondary'
     * }
     * const selectKnob: ButtonVariant = select('variant', ButtonVariant, ButtonVariant.Primary);
     */
    export function select<EnumT extends {}, ResultT = EnumT[keyof EnumT]>(
        name: string,
        options: EnumT,
        value: ResultT,
        groupId?: string
    ): ResultT;
}

Describe alternatives you've considered

• writing a function that creates a select knob out of an enum, its default value and name

Are you able to assist bring the feature to reality?
I can create a PullRequest, suppose I'd find time on the weekend.
If this is a wanted feature.

Additional context
the TS Error I get currently:

TS2345: Argument of type 'typeof ButtonVariant' is not assignable to parameter of type 'readonly ButtonVariant.primary[]'.   Type 'typeof ButtonVariant' is missing the following properties from type 'readonly ButtonVariant.primary[]': length, concat, join, slice, and 16 more

[shilman]

Is this addressed by #7411 ??

[emilio-martinez]

Addressed in #7411.

[shilman]

Son of a gun!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.2.0-beta.1 containing PR #7411 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.

Closing this issue. Please re-open if you think there's still more to do.