Add string function to test suite
Add string function to test suite

SkySkimmer/coq,ejgallego/coq,Zimmi48/coq,ejgallego/coq,coq/coq,ejgallego/coq,SkySkimmer/coq,SkySkimmer/coq,coq/coq,coq/coq,ejgallego/coq,Zimmi48/coq,coq/coq,Zimmi48/coq,SkySkimmer/coq,Zimmi48/coq