C++ 多 CPU 架构的单元测试

Question

we develop an app in C++ for ARM and x86 architectures. Of course we integration test our app for both architectures but for now we unit test our app only on x86. Is this a possible error source and is it normal to run unit tests for all supported architectures?

Answer 1

In theory, as long as your code only uses C++ and you have no undefined behavior, the code should behave the same on all compliant platforms. That's what the standard is supposed to do.

In practice little code is completely contained (you might use libraries or drivers that can behave differently on different platforms) or is absolutely free of undefined behavior (ie int overflow is undefined behavior and it can change with the platform, pointer size can change with the platform, I think there's a flag to issue warnings or errors for all undefined behavior). Even then because of such differences you might get slightly different data-structures layout and you might find some memory or performance issues.

It depends on your code and how much you care about all the platforms. If it's mission critical that it works flawless on both platforms then you should run the tests on both. If you are mostly dependency and undefined behavior free then maybe a single platform might be enough.

You can also try a setup where you unit test on what you have but every now and then (say daily or weekly) you run the test on the other platform to make sure everything is still fine.