There are two types of tests in this project:
trybuild tests, which verify that the macro code can be compiled, or when there is a problem, the compiler errors are properly reported. The test cases are in the varnish/tests -- pass/*.rs work by default, pass-ffi/*.rs work only with the ffi feature is enabled, and fail/*.rs should fail. The expected errors are in the fail/*.stderr files. To update the expected output, run just bless.
insta tests, which verify that the macros produce the correct output when used correctly, and also that the output is stable. The test uses the same pass and pass-ffi files, and the expected output is in the varnish/snapshots/*.snap files. The test runner must be part of the crate itself due to it being proc-macro, so it is located in varnish-macros/src/tests.rs. To update the snapshots, use the same just bless command. Make sure to install insta first.
The simplest way to observe generated code is to examine varnish/sanshots/*@code.snap files. They contain code generated from the varnish/test/pass/*.rs files. Additionally, the model file describes intermediate parse result of the test file, json files shows the data given to the Varnish vmod compiler, and docs contain the generated documentation.
For a more in-depth look, use cargo expand command. You will need to run cargo install cargo-expand to install it first. You can copy/paste the expanded code into the same file, removing some boilerplate before and after the expanded code, and then run cargo check to see the errors. Note that some expansions cannot be compiled - e.g. anything expanded from format! or panic! - so you may need compare the generated code with the original, and keep all the original parts for anything unrelated to the generated code.
Note that the test cases in varnish/tests will not work with cargo expand unless you make it part of the regular compilation. For example, let's say we want to debug varnish/test/pass/object.rs. Modify varnish/tests/compiler.rs like this:
#[path = "pass/object.rs"]
mod try_to_build;Once you have done that, you can run the following command to save generated code to a file:
cargo expand -p varnish --test compile --tests try_to_build > varnish/tests/pass/object.expanded.rsDelete the top 2 lines with mod try_to_build { and the last }, and reformat object.expanded.rs before comparing it with object.rs to see the resulting code. Now, modify the path in the compiler.rs to point to the expanded file, and you should be able to run cargo check --tests to see the errors.
Docker allows multiple Varnish versions on the same machine. To use it, run just docker-run-76 or any other version (run just to see a list). On the first run, it will build the image, install needed dependencies, and then it will start the container. The container will have the git root directory mounted as /app, so you can run cargo build and cargo test as usual. All work is preserved in the docker/.cache/<version>, so restarting container would not need re-install everything.