TEST: convertion unit tests into run tests

backend.native/tests/codegen/function/sum_foo_bar.kt

@@ -1,4 +1,8 @@
 fun foo(a:Int):Int = a
 fun bar(a:Int):Int = a
 
-fun sumFooBar(a:Int, b:Int):Int = foo(a) + bar(b)
+fun sumFooBar(a:Int, b:Int):Int = foo(a) + bar(b)
+
+fun main(args:Array<String>) {
+    if (sumFooBar(2, 3) != 5) throw Error()
+}