reactHOCExampleClass.tsx

type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;

type Theme = {
  fontColor: string;
};

type WithThemeProps = {
  theme: Theme;
};

const withTheme = <P extends object>(Component: React.ComponentType<P>) =>
  class WithTheme extends React.Component<Omit<P, keyof WithThemeProps>> {
    render() {
      return <Component {...this.props as P} theme={theme} />;
    }
  };