mockers | Mocking library for Rust | Mock library

I am mocking a class and would like to redirect calls ,but an error occured mean no matching function for call，code like this：

How to query a map of type Map in JSON form, in MongoDB?

Sample JSON:

I'm trying to retrieve the the first part of this text Book I\n Psalms 1–41\n Psalm 1\n using a non greedy regex (.+)[? but it highlights everything, any help will be appreciated, thanks!

Book I\n Psalms 1–41\n Psalm 1\n [1] Blessed is the one\n who does not walk in step with the wicked\n or stand in the way that sinners take\n or sit in the company of mockers,\n [2] but whose delight is in the law of the Lord,\n and who meditates on his law day and night.\n [3] That person is like a tree planted by streams of water,\n which yields its fruit in season\n and whose leaf does not wither—\n whatever they do prospers.\n \n [4] Not so the wicked!\n They are like chaff\n that the wind blows away.\n [5] Therefore the wicked will not stand in the judgment,\n nor sinners in the assembly of the righteous.\n \n [6] For the Lord watches over the way of the righteous,\n but the way of the wicked leads to destruction.\n"