Web developer job interview questions

I was given two questions required to submit prior to the interview. If you could give me some ideas it'd help me a lot. Thanks.

1. One is in the situation where Restful API has to be provided but the server is not ready or fully developed yet. Then in this case, how can one provide service to Front-End first?

2. One is in the situation where database isn't ready or fully developed yet. How then can one find the way to test whether his or her developed service is working well with the database?

Thank you.