Override React's `isRequired` prop type validation. Allows you to express "If not X, than A, B, C".

overridePropValidation.js

// Override the `isRequired` validation of a list of props for another, single
// prop. For example, if you had a number of props used to generate a URL path,
// you could require all of them *unless* a full path was passed as a prop.
//
// @param {array} toOverride - Array of strings to 'override', or ignore.
// @param {function} [type] - PropType validation function. Optional.
// @param {boolean} [required] - Validate the prop as required. Optional.
//
// @returns {function} Callback function for custom prop validation.
//                     See the `customProp` in http://bit.ly/1nhwVQ3.
export default function overridePropValidation(toOverride, type, required) {
  return (props, name, component, location) => {
    // If the prop wasn't passed, validate all other keys were.
    if (!props[name]) {
      // If not, throw an error.
      if (!hasAllKeys(props, toOverride)) {
        return new Error(
          `${component} requires either a ${name} prop, or the following
          attributes as props: (${toOverride.join(', ')}).`
        );
      }

      return null;
    }

    if (!type) {
      return null;
    }

    if (required) {
      return type.isRequired(props, name, component, location);
    }

    return type(props, name, component, location);
  };
}

// Check if a `list` has all `keys`.
//
// @param {object|array} list - List of keys, or array.
// @param {array} keys - Array of keys to check exist in `list`.
//
// @returns {boolean} `true` if all keys exist, `false` if they don't.
const hasAllKeys = (list, keys) => {
  // Assume if `list` isn't an array, it's an object.
  if (toString.call(list) !== '[object Array]') {
    list = Object.keys(list);
  }

  for (let key of keys) {
    if (list.indexOf(key) === -1) {
      return false;
    }
  }

  return true;
};