Xcode unit test compile-time error in Swift -

swift's advanced type-checking has ushered entire coding practice of maximizing compile-time type-checking.

a lot has been said traditional unit-testing vs. type-safety in code. find myself on type-safety side of equation, i.e., i've been trying make code raise many compile-time errors possible when used incorrectly.

however i'm wondering if there's way unit-test type-safety itself.

of course, type-safety errors exhibited compile-time errors. therefore, boils down unit-testing compile-time errors.

there answer achieving make in c++: unit test compile-time error

ideally, able following:

struct username: stringish{ ... } struct sqlquery: stringish{ ... }  ...  xctassertuncompilable{     func foo(a: username, b: sqlquery) {         ...         if (a == b) { ... } // error: cannot compare type username type sqlquery }  xctassertuncompilable{     let user1 = username("joe")     let selectallusers = sqlquery("select * users")      user1 == selectallusers // error: cannot compare type username type sqlquery } 

this bit more can hacked without serious support xcode-side.

so next best thing have similar solution presented in link before, i.e. separate script can test whether or not specific files can compile. of course, have able import proper frameworks/packages.

i'd happy idea of how make such script ios-swift without of hassle.

bonus points if can automatically called during usual testing phase of xcode. bonus points if "real" testing passes if external script passes.