Macros to execute compiled program don't force it to quit when test exits

还没有人认领这个 Issue。

If main has an infinite loop, it'll just keep running as a process in the background even after the test has failed.

This became obvious in Paint Milestone 4 tests when a window was displayed. Here's how I solved it (although in this case I was looking for a timeout):

TEST(PaintProgramTest, StartShowsImage) {
std::chrono::time_point start, end;
start = std::chrono::system_clock::now();
system("timeout 1s ./main");
end = std::chrono::system_clock::now();
std::chrono::duration elapsed_seconds = end - start;
std::chrono::milliseconds ms =
std::chrono::duration_cast(elapsed_seconds);
if (ms.count() <= 900) {
FAIL() << " main() should call PaintProgram::Start() which calls "
"Image::ShowUntilClosed().";
}
}

首先定位执行已编译程序的测试宏，以及报告中所示的 TEST 用例。使用 main 包含无限循环的程序重现该故障，然后检查宏如何启动并观察该进程。完成的标准是：失败或退出的测试不会让已编译程序继续在后台运行。

由索引模型根据 Issue 内容生成。