enforceExternalToolsAvailable

import std.exception : assertThrown;

struct Caller
{
    @ExternalDependency("/this/is/missing")
    @ExternalDependency("this_too_is_missing", "mypack", "http://example.com/")
    void makeCall() { }
}

assertThrown!ExternalDependencyMissing(enforceExternalDepencenciesAvailable!Caller());
// Error message:
//
//     missing external tools:
//     - /this/is/missing
//     - this_too_is_missing (part of `mypack`; see http://example.com/)
//
//     Check your PATH and/or install the required software.