Ares uses a Nix developer shell to set up the environment for rust builds. Please [Install Nix](https://nixos.org/download#download-nix).
With Nix installed, you can run
```bash
nix develop
```
in `rust/` or any subdirectory, and you will be dropped into a BASH shell with the build environment set up. This will provide proper versions of non-rust dependencies, as well as the rust environment.
To build Ares, start a nix development shell as above. Within the shell, in the `rust/ares` directory, you can run:
```bash
cargo build
```
to build the Ares executable. This will place the built executable at `target/debug/ares` under the `rust/ares` directory.
Ares is made to run as an urbit "serf", meaning it is intended to be invoked by a "king" which sends it commands and performs side-effects specified by its output. We use the vere king. Special instructions for building the vere king to invoke Ares are forthcoming.
The command to run the Ares suite of unit tests is:
```bash
cargo test --verbose -- --test-threads=1
```
The tests must be run with `-- --test-threads=1` because Rust does not have any way to specify test setup / teardown functions, nor does it have any way to
specify ordered test dependencies. Therefore, the only way to ensure that tests that share resources don't clobber each other **and** that tests setup / teardown in the right order is to force all unit tests to be single-threaded.
### Style
Ares uses the default Rust formatting and style. The CI jobs are configured to reject any code which produces linter or style warnings. Therefore, as a final step before uploading code changes to GitHub, it's recommended to run the following commands:
```bash
cargo fmt
cargo clippy --all-targets --no-deps -- -D warnings -A clippy::missing_safety_doc
```
This will auto-format your code and check for linter warnings.
Until terminated with ctrl-c, this will rebuild Ares library on any change to the underlying source files and report any warnings and errors. It will *not* produce the executable. You must run the build command above to rebuild the executable.
## Hoon
The Nock analysis and lowering for Ares is written in Hoon, and lives at `hoon/codegen.` It is meant to be jammed and included in the Ares binary. (See [`src/load.rs`](rust/ares/src/load.rs) in the Rust sources for details.)
If the hoon source has been synced to a desk, e.g. `sandbox`, on a fakezod, then the build generator can be invoked as:
```
.cg/jam +sandbox!cg-make
```
This will build the Hoon standard library and the Ares Nock analysis as a "trap" meant to be run by Ares. The jammed output can be found at `<fakezod-pier>/.urb/put/cg.jam`, and should be copied to the `rust/ares/bin` directory, from whence the rust build will include it in the executable.
Instructions on testing the analysis in a fakezod are forthcoming.
