From 1478be14c7bf4e688d48d78c1b4816f8b43ac69d Mon Sep 17 00:00:00 2001
From: Joel Linn <jl@conductive.de>
Date: Wed, 9 Mar 2022 23:49:27 +0100
Subject: [PATCH] [Base] Add chrono tests

---
 src/xenia/base/testing/chrono_test.cc | 148 ++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 src/xenia/base/testing/chrono_test.cc

diff --git a/src/xenia/base/testing/chrono_test.cc b/src/xenia/base/testing/chrono_test.cc
new file mode 100644
index 000000000..a63aac53c
--- /dev/null
+++ b/src/xenia/base/testing/chrono_test.cc
@@ -0,0 +1,148 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2022 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/base/chrono.h"
+
+#define CATCH_CONFIG_ENABLE_CHRONO_STRINGMAKER
+#include "third_party/catch/include/catch.hpp"
+
+namespace xe::base::test {
+
+// If the tests run fast, the time duration may be zero. So we artificially
+// raise it to allow for some error.
+template <typename _Rep, typename _Period>
+auto dur_bound(std::chrono::duration<_Rep, _Period> dur) {
+  using namespace std::chrono_literals;
+  return std::max<std::common_type_t<std::chrono::milliseconds,
+                                     std::chrono::duration<_Rep, _Period>>>(
+      dur, 1ms);
+}
+
+TEST_CASE("WinSystemClock <-> system_clock", "[clock_cast]") {
+  using namespace xe::chrono;
+  using namespace date;
+  using sys_clock = std::chrono::system_clock;
+
+  // First check some assumptions made in chrono.h
+
+  SECTION("C++20 unix epoch") {
+    auto epoch = date::year{1970} / date::month{1} / date::day{1};
+    std::chrono::system_clock::time_point epoch_tp{
+        static_cast<date::sys_days>(epoch)};
+    REQUIRE(epoch_tp.time_since_epoch().count() == 0);
+  }
+
+  SECTION("Epoch delta") {
+    std::chrono::seconds sys_delta = WinSystemClock::unix_epoch_delta();
+    REQUIRE(sys_delta.count() == INT64_C(-11644473600));
+  }
+
+  SECTION("1993/12/21") {
+    static constexpr sys_days sys(1993_y / dec / 21);
+
+    static constexpr auto wsys = WinSystemClock::from_sys(sys);
+    REQUIRE(wsys.time_since_epoch().count() == 124009056000000000);
+
+    REQUIRE(clock_cast<sys_clock>(wsys) == sys);
+    REQUIRE(clock_cast<WinSystemClock>(sys) == wsys);
+  }
+
+  SECTION("2100/3/1") {
+    static constexpr sys_days sys(2100_y / mar / 1);
+
+    static constexpr auto wsys = WinSystemClock::from_sys(sys);
+    REQUIRE(wsys.time_since_epoch().count() == 157520160000000000);
+
+    REQUIRE(clock_cast<sys_clock>(wsys) == sys);
+    REQUIRE(clock_cast<WinSystemClock>(sys) == wsys);
+  }
+}
+
+TEST_CASE("WinSystemClock <-> XSystemClock", "[clock_cast]") {
+  using namespace std::chrono_literals;
+  using namespace xe::chrono;
+  using namespace date;
+  using sys_clock = std::chrono::system_clock;
+
+  SECTION("1993/12/21, clock_no_scaling = true") {
+    static constexpr sys_days sys(1993_y / dec / 21);
+    cvars::clock_no_scaling = true;
+    Clock::set_guest_time_scalar(1.0);
+
+    static constexpr auto wsys = WinSystemClock::from_sys(sys);
+
+    auto start = std::chrono::system_clock::now();
+
+    auto xsys = date::clock_cast<XSystemClock>(wsys);
+    auto wxsys = date::clock_cast<WinSystemClock>(xsys);
+
+    auto duration = dur_bound(std::chrono::system_clock::now() - start);
+
+    auto error = wsys.time_since_epoch() - wxsys.time_since_epoch();
+    REQUIRE(error < duration);
+    REQUIRE(error > -duration);
+  }
+
+  SECTION("1993/12/21, clock_no_scaling = false") {
+    static constexpr sys_days sys(1993_y / dec / 21);
+    cvars::clock_no_scaling = false;
+    Clock::set_guest_time_scalar(1.0);
+
+    static constexpr auto wsys = WinSystemClock::from_sys(sys);
+
+    auto start = std::chrono::system_clock::now();
+
+    auto xsys = date::clock_cast<XSystemClock>(wsys);
+    auto wxsys = date::clock_cast<WinSystemClock>(xsys);
+
+    auto duration = dur_bound(std::chrono::system_clock::now() - start);
+
+    auto error1 = wsys.time_since_epoch() - xsys.time_since_epoch();
+    auto error2 = xsys.time_since_epoch() - wxsys.time_since_epoch();
+    auto error3 = wsys - wxsys;
+
+    REQUIRE(error1 < 10ms);
+    REQUIRE(error1 > -10ms);
+    REQUIRE(error2 < 10ms);
+    REQUIRE(error2 > -10ms);
+    REQUIRE(error3 < duration);
+    REQUIRE(error3 > -duration);
+  }
+}
+
+}  // namespace xe::base::test
+
+// only make these available now
+#include "xenia/base/chrono_steady_cast.h"
+
+namespace xe::base::test {
+
+TEST_CASE("WinSystemClock <-> steady_clock", "[clock_cast]") {
+  using namespace xe::chrono;
+  using namespace date;
+  using sty_clock = std::chrono::steady_clock;
+
+  // steady conversion is mostly used to convert wait times
+
+  SECTION("now") {
+    auto sty = sty_clock::now();
+
+    // Because steady casts are imprecise, we need to allow some margin of error
+    auto start = sty_clock::now();
+
+    auto wsty = clock_cast<WinSystemClock>(sty);
+    auto sty2 = clock_cast<sty_clock>(wsty);
+
+    auto duration = dur_bound(sty_clock::now() - start).count();
+    auto error = std::abs((sty2 - sty).count());
+    REQUIRE(error <= duration);
+  }
+}
+
+}  // namespace xe::base::test