Writing an OS in Rust: Testing

by pcr910303 • 7 years ago

173 9 7 years ago

phil-opp5• 7 years ago

Author here. This post is a rewrite of the previous Unit Testing [1] and Integration Tests [2] posts. It creates a custom test framework that runs test functions inside QEMU, so that they run in a realistic environment (compared to running on the host system).

[1] https://os.phil-opp.com/unit-testing/ [2]: https://os.phil-opp.com/integration-tests/

The new test framework directly works with `cargo xtest`, which brings the project closer to using standard cargo programs for building, testing, and running. The last remaining step is the `std` Aware Cargo RFC [3]. When the RFC is merged and implemented, cargo-xbuild will no longer be needed and the familiar cargo build, cargo run, and cargo test commands will just work, including IDE integration.

[3] https://github.com/rust-lang/rfcs/pull/2663

rstevens24• 7 years ago

Just wanted to say thanks so much for your blog posts! I have been working on a medical device in no_std Rust and your articles have been super helpful in setting up a robust unit test suite. I have been trying to hack at the utest crate and get on-device integration tests running again for quite some time... good to know there is movement on the custom test runner front :)

phil-opp5• 7 years ago

It's the first time that I hear about Rust on medical devices. Sounds really interesting! I'm glad to hear that my blog was useful to you!

I have been trying to hack at the utest crate and get on-device integration tests running again for quite some time... good to know there is movement on the custom test runner front :)

The custom test framework feature of Rust was silently introduced in https://github.com/rust-lang/rust/pull/53410 and I didn't know that it even existed a month ago. But it works really well and seems like a good solution for your problem.

aey2• 7 years ago

How did you deal with lack of allocation errors?

In my mind, what would make rust a fanatic kernel language is tracking allocators with types at the compiler level like it does for Send and Sync.

phil-opp5• 7 years ago

There is some minimal support for fallible allocation through the try_reserve method on various collections. See https://github.com/rust-lang/rust/issues/48043 for more information.

Other than that, there is ongoing work for custom allocator support in collections: https://github.com/rust-lang/rust/issues/42774. Maybe that's what you meant with tracking the allocators at the type level?

It's of course also possible to create own fallible collection types, for example as a wrapper around the normal liballoc and try_reserve.

_wwpm• 7 years ago

I’ve started writing my own OS with this tutorial for a school project with a friend. It is a big help! Our next step now is the GDT

https://github.com/oyagci/kfs/tree/dev

phil-opp5• 7 years ago

Great to hear that!

Writing an OS in Rust: Testing

Related Stories