How do I call a nested function from another file in typescript

file1:

export func foo1 {
    const foo2 { return something}
    return foo1something
}

I just want to test this foo2 individual function in my test file:

file2:

import { foo1 } from '../file1';

Now how do I access foo2 here?

Your Import looks fine and the problems does not relate to "different files" or the "import".

let and const or nested functions are block-scoped
so they cannot be accessed outside of the original function.

they are only available in the nested function (the block-scope).

You can call the inner function inside the oute function itself.

export function foo() {
    console.log('foo');
    function bar() {
        return `bar`;
    }
    return bar()
}

console.log(foo());

result:
foo
bar

You can declare a object or class with nested functions or methods as properties and call it from the "outside":

File1:

export const someObject = {
  foo: () => { console.log('foo') },
  bar: () => { console.log('bar') }
}

File2:

import { someObject } from "./File1";

someObject.foo();
someObject.bar();

result:
foo
bar