UnitTests: Add custom main that calls RegisterMsgAlertHandler

This prevents a failed assertion from hanging on the MSVC buildbots.

Source/UnitTests/CMakeLists.txt

@@ -4,6 +4,8 @@ add_custom_command(TARGET unittests POST_BUILD COMMAND ${CMAKE_CTEST_COMMAND})
 
 string(APPEND CMAKE_RUNTIME_OUTPUT_DIRECTORY "/Tests")
 
+add_library(unittests_main OBJECT UnitTestsMain.cpp)
+target_link_libraries(unittests_main PUBLIC fmt gtest)
 # Since this is a Core dependency, it can't be linked as a normal library.
 # Otherwise CMake inserts the library after core, but before other core
 # dependencies like videocommon which also use Host_ functions, which makes the
@@ -16,7 +18,7 @@ macro(add_dolphin_test target)
     $<TARGET_OBJECTS:unittests_stubhost>
   )
   set_target_properties(${target} PROPERTIES FOLDER Tests)
-  target_link_libraries(${target} PRIVATE core uicommon gtest_main)
+  target_link_libraries(${target} PRIVATE core uicommon unittests_main)
   add_dependencies(unittests ${target})
   add_test(NAME ${target} COMMAND ${target})
 endmacro()

Source/UnitTests/UnitTests.vcxproj

@@ -36,8 +36,8 @@
   <ItemGroup>
     <!--gtest is rather small, so just include it into the build here-->
     <ClCompile Include="$(ExternalsDir)gtest\src\gtest-all.cc" />
-    <ClCompile Include="$(ExternalsDir)gtest\src\gtest_main.cc" />
     <!--Lump all of the tests (and supporting code) into one binary-->
+    <ClCompile Include="UnitTestsMain.cpp" />
     <ClCompile Include="Common\BitFieldTest.cpp" />
     <ClCompile Include="Common\BitSetTest.cpp" />
     <ClCompile Include="Common\BitUtilsTest.cpp" />

Source/UnitTests/UnitTestsMain.cpp

@@ -0,0 +1,30 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Based on gtest_main.cc
+
+#include <cstdio>
+#include <fmt/format.h>
+
+#include "Common/MsgHandler.h"
+
+#include "gtest/gtest.h"
+
+namespace
+{
+bool TestMsgHandler(const char* caption, const char* text, bool yes_no, Common::MsgType style)
+{
+  fmt::print(stderr, "{}\n", text);
+  ADD_FAILURE();
+  // Return yes to any question (we don't need Dolphin to break on asserts)
+  return true;
+}
+}  // namespace
+
+int main(int argc, char** argv)
+{
+  fmt::print(stderr, "Running main() from UnitTestsMain.cpp\n");
+  Common::RegisterMsgAlertHandler(TestMsgHandler);
+
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}