Cargo config.toml different runner for tests

tools and infrastructure cargo
1

I would like to use a different runner for tests. It would be really convenient to test Wasm files. I would imagine something like this to work:

[target.'cfg(not(test))']
runner = "default_runner"

[target.'cfg(test)']
runner = "test_runer"

Unfortunately, the default_runner is always used, even when running cargo test. Is there maybe a workaround for this? A different cfg that could be used?

2

I don't think there is. In a wrapper around the runner maybe you could check if the wasm file exists in the test directory of the build dir and then dispatch to the right runner?

1 Like
3

Thanks for the suggestion, this sounds like an ok tradeoff for now. I just can't find a test sub-directory in the build one. When I run cargo test the .wasm file is generated in the deps folder: target/wasm32-wasi/debug/deps/name-hash.wasm.

I'm just worried when the runner is used outside of the cargo structure that relaying on such a common name as deps may create an issue. I think I will combine it with detecting a cargo set environment variable, like $CARGO_MANIFEST_DIR to harden a bit the detection.

Are there any other cargo commands that generate their builds inside of the deps directory, like test? cargo run? cargo run --example? cargo xxx? Just to check if I'm missing an obvious case where this approach would fail?

EDIT: Sadly, cargo bench uses the same build directory. So you also need to check for a --bench flag.

EDIT2: Running cargo test --example <name> can't be covered with this approach, because it will end up in the examples build directory.