lumiera_documentation/tests/library/test/test-helper-variadic-test.cpp
Ichthyostega 9c74466778 Tests: build an link a test-support library
This is something I wanted to clean-up since a very long time indeed,
but always postponed it, since it requires a lot of nasty clean-up and disentangling....

Several parts had been stashed away into `src/lib/test`, which are not really related:
 * the testrunner and testsuite builder
 * generic helper utilities
 * specialised test-support facilities, e.g. the EventLog

This changeset introduces a new top-level test folder and a namespace `::test`
Code from this folder is linked into a shared library `libtestsupport.so`,
which resides in the linkage hierarchy between »Vessel« and »Vault«,
yet is no longer part of the Lumiera application and only linked into the test-suite.
2026-03-06 23:16:32 +01:00

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/*
TestHelperVariadic(Test) - verify variadic template diagnostics helper
Copyright (C)
2014, Hermann Vosseler <Ichthyostega@web.de>
  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.
* *****************************************************************/
/** @file test-helper-variadic-test.cpp
** unit test \ref TestHelperVariadic_test
*/
#include "test/run.hpp"
#include "test/test-helper.hpp"
#include <iostream>
#include <utility>
#include <string>
#include <cmath>
using std::cout;
using std::string;
using test::showVariadicTypes;
namespace lib {
namespace test{
namespace test{
namespace { // test fixture...
class Interface
{
public:
Interface(){}
Interface(Interface const& o) { cout << "COPY.CT from "<<&o<<" !!!\n"; }
Interface(Interface const&& o) { cout << "MOVE.CT from "<<&o<<" !!!\n"; }
Interface& operator= (Interface const& o) { cout << "COPY= from "<<&o<<" !!!\n"; return *this; }
Interface& operator= (Interface const&& o) { cout << "MOVE= from "<<&o<<" !!!\n"; return *this; }
virtual ~Interface() { }
};
class Impl
: public Interface
{
string s_;
public:
Impl(string ss ="ZOMG") : s_(ss) { }
};
inline double
makeRvalue()
{
return atan2(0,-0.0);
}
}//(End) test fixture
/****************************************************************************//**
* @test document usage of the diagnostics helper for variadic templates.
* Errors in variadic template instantiations are sometimes hard to spot,
* due to the intricacies of template argument matching and the
* reference collapsing rules. Our diagnostics facility is itself a
* variadic function template, which, when supplied with an argument pack,
* will build a diagnostic string describing the arguments.
* @warning care has to be taken to pass the template arguments properly,
* since template argument matching might mess up the reference kind
* (rvalue, lvalue) of the passed types. Thus, either use std::forward,
* or spell out the template argument(s) explicitly on invocation
*
* @see showVariadicTypes()
* @see TestHelper_test
*/
class TestHelperVariadic_test : public Test
{
virtual void
run (Arg)
{
double d = makeRvalue();
double const& cr = d;
Impl obj;
Interface const& ref = obj;
cout << "--no-arg--\n" << showVariadicTypes() <<"\n";
cout << "--reference--\n" << showVariadicTypes(d) <<"\n";
cout << "--value--\n" << showVariadicTypes(makeRvalue()) <<"\n";
forwardFunction("two values", "foo", 42L); // displayed as char [4] const&, long &&
forwardFunction("references", d,cr,std::move(d)); // displayed as double&, double const&, double &&
forwardFunction("baseclass", ref); // displayed as Interface const&
}
/** this dummy simulates a typical variadic call
* which takes all arguments as '&&' for the purpose of "perfect forwarding"
*/
template<typename... ARGS>
void
forwardFunction (string id, ARGS&&... args)
{
cout << "--"<<id<<"--\n"
<< showVariadicTypes (std::forward<ARGS>(args)...)
<< "\n"
;
}
};
/** Register this test class... */
LAUNCHER (TestHelperVariadic_test, "unit common");
}}} // namespace lib::test::test