feat: extract default props from destructuring

[nekitk]

Fixes #154

Added support for extracting default prop values from object desctructuring inside functional components.

[nekitk]

upped version because current version was exiting with Error: Cannot find any-observable implementation nor global.Observable.

[nekitk]

Deleted these 2 tests (should parse referenced props and supports spread props) because this use cases are not actually supported and default props are not properly generated. These tests were not failing on master because of incorrect check inside test code itself: see https://github.com/styleguidist/react-docgen-typescript/pull/200/files#diff-a063097dc09ae77820847611faefb99b

[pvasek]

Thanks for explanation.

[nekitk]

merging multiple definitions in case of defaultProps are used together with desctructuring

[pvasek]

The version including this code has been published to npm as v1.13.0.

[rmunch]

Thank you for adding this feature - very useful! Something I notice is that if you destructure props inside the function rather than in the declaration, default props are not picked up. Would it make sense to support this case?

import * as React from "react";

interface ButtonProps {
    children: React.ReactNode,
    /** More information about the disabled property */
    disabled?: boolean
}

# Default props detected:
export default function Button({children, disabled = false}: ButtonProps) {
    return <button disabled={disabled}>{children}</button>;
}

# Default props not detected:
export default function Button(props: ButtonProps) {
    const {children, disabled = false} = props;
    return <button disabled={disabled}>{children}</button>;
}

[nekitk]

@rmunch It is certainly possible to support this case, but there's no need in it right now on my current project. If you would try to add it yourself, I think you need to find an assignment statement with 'props' on the right side, take the left side and then pass its properties to this. getPropMap. Similar to the way defaultProps are parsed.