How can i write test case for function fetch_github_info in Offchain worker example

[CocDap]

Hello, I try to write a test case for checking function fetch_github_info in offchain worker. But it failed.

#[test]                                                                                                              
fn fetch_submit_info_works() {                                                                                       
      let (mut t, _, _) = ExternalityBuilder::build();                                                                 
      t.execute_with(|| {                                                                                              
            System::set_block_number(4);
            assert_ok!(OcwDemo::fetch_github_info())
});
}

It catch Error in line 405 that Response doesnt response from API in function fn fetch_from_remote()

But when I check in Polkadot.js.org it works and has fetched data from API
Can you have any idea to fix this?
I updated, but it failed because data stores in offchain worker has None

Thank you very much