1.for searchFriends(), you need to return a list of Users not just a singular user since there could be multiple users matching that searchString.
2. in your getUserFromID(), you need to set values to null if they don't exist in firebase. Ex:
let myResponses = userData["myResponses"] as? [String] ?? []
3. in getIncomingRequests. make sure the collection is "USERS" not "users" since Firebase querying is case sensitive.
4. [Optional] If you want to add more test cases for testing anything, feel free to do so. Good job writing your own test case!

good job!