TestArgs<T, O>:
    | []
    | [name: string]
    | [cb: ((t: T) => any) | false]
    | [extra: O]
    | [name: string | number, cb: ((t: T) => any) | false]
    | [name: string | number, extra: O]
    | [extra: O, cb: ((t: T) => any) | false]
    | [name: string | number, extra: O, cb: false | ((t: T) => any), defaultName?: string]

Argument signatures that may be passed to a subtest method.

If a callback is not provided, then the test is marked as todo.

Type Parameters