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tests.h
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1// -*- lsst-c++ -*-
2
3/*
4 * This file is part of utils.
5 *
6 * Developed for the LSST Data Management System.
7 * This product includes software developed by the LSST Project
8 * (https://www.lsst.org).
9 * See the COPYRIGHT file at the top-level directory of this distribution
10 * for details of code ownership.
11 *
12 * This program is free software: you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation, either version 3 of the License, or
15 * (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program. If not, see <https://www.gnu.org/licenses/>.
24 */
25
26#ifndef LSST_CPPUTILS_TESTS_H
27#define LSST_CPPUTILS_TESTS_H
28
29// Do not include unit_test.hpp, to avoid definition problems with BOOST_TEST_MODULE
30
31#include <ostream>
32#include <type_traits>
33
34namespace lsst {
35namespace cpputils {
36
37namespace {
38// Variable template reporting whether a type can be printed using <<
39// Second template parameter is a dummy to let us do some metaprogramming
40template <typename, typename = void>
41constexpr bool HAS_STREAM_OUTPUT = false;
42template <typename T>
43constexpr bool HAS_STREAM_OUTPUT<
44 T, std::enable_if_t<true, decltype((void)(std::declval<std::ostream&>() << std::declval<T&>()),
45 void())>> = true;
46
47// Conditional function templates reporting object values if possible
48template <typename T, class Hash>
49std::enable_if_t<HAS_STREAM_OUTPUT<T>> printIfHashEqual(T obj1, T obj2, Hash hash) {
50 BOOST_TEST_REQUIRE(obj1 == obj2);
51 BOOST_TEST(hash(obj1) == hash(obj2),
52 obj1 << " == " << obj2 << ", but " << hash(obj1) << " != " << hash(obj2));
53}
54template <typename T, class Hash>
55std::enable_if_t<!HAS_STREAM_OUTPUT<T>> printIfHashEqual(T obj1, T obj2, Hash hash) {
56 if (!(obj1 == obj2)) {
57 BOOST_FAIL("Unequal objects need not have equal hashes.");
58 }
59 BOOST_TEST(hash(obj1) == hash(obj2));
60}
61} // namespace
62
71template <typename T>
72constexpr void assertValidHash() {
73 using namespace std;
74 using Hash = hash<remove_cv_t<T>>;
75
77 "std::hash specializations must be default-constructible");
78 static_assert(is_copy_assignable<Hash>::value, "std::hash specializations must be copy-assignable");
79 // Swappability hard to test before C++17
80 static_assert(is_destructible<Hash>::value, "std::hash specializations must be destructible");
81
83 "std::hash must have an argument_type member until C++20");
85 "std::hash must have a result_type member until C++20");
86 // Ability to call Hash(T) hard to test before C++17
87 static_assert(is_same<std::invoke_result_t<Hash, T>, size_t>::value,
88 "std::hash specializations must be callable and return a size_t");
89}
90
101template <typename T>
102void assertHashesEqual(T obj1, T obj2) {
103 using Hash = std::hash<std::remove_cv_t<T>>;
104
105 printIfHashEqual(obj1, obj2, Hash());
106}
107
108} // namespace cpputils
109namespace utils = cpputils;
110} // namespace lsst
111
112#endif
T declval(T... args)
void assertHashesEqual(T obj1, T obj2)
Test that equal objects have equal hashes.
Definition tests.h:102
constexpr void assertValidHash()
Compile-time test of whether a specialization of std::hash conforms to the general spec.
Definition tests.h:72
STL namespace.