Add tests for String::substr
Add tests for String::substr

black78/taglib,black78/taglib,dlz1123/taglib,pbhd/taglib,TsudaKageyu/taglib,videolabs/taglib,MaxLeb/taglib,i80and/taglib,taglib/taglib,videolabs/taglib,taglib/taglib,pbhd/taglib,MaxLeb/taglib,Distrotech/taglib,davispuh/taglib,davispuh/taglib,i80and/taglib,Distrotech/taglib,davispuh/taglib,TsudaKageyu/taglib,dlz1123/taglib,TsudaKageyu/taglib,i80and/taglib,pbhd/taglib,black78/taglib,dlz1123/taglib,videolabs/taglib,taglib/taglib,MaxLeb/taglib,Distrotech/taglib