Using cargo build scripts

Testing sdk also has the interface for cargo build scripts. Some IDEs can analyze files generated in build scripts, providing code completion and error highlighting for code generated in build scripts. But using it may be a little bit tricky because build scripts are not designed for such things.

To set up IDE you need to do the following:

CLion:

• in the Help -> Actions -> Experimental Futures enable org.rust.cargo.evaluate.build.scripts
• refresh cargo project in order to update generated code: change Cargo.toml and build from IDE or press Refresh Cargo Project in Cargo tab

VS Code:

• install the rust-analyzer plugin
• change Cargo.toml to let plugin update code from generated files

The update will not work instantly: you should build service to wasm, and then trigger build.rs run again, but for the native target.

And here is the example of using this:

build.rs

rust
use marine_rs_sdk_test::generate_marine_test_env;
use marine_rs_sdk_test::ServiceDescription;
fn main() {
    let services = vec![ // <- 1
        ("greeting".to_string(), ServiceDescription {
            config_path: "Config.toml".to_string(),
            modules_dir: Some("artifacts".to_string()),
        })
    ];
    let target = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap();
    if target != "wasm32" { // <- 2
        generate_marine_test_env(services, "marine_test_env.rs", file!()); // <- 3
    }
    println!("cargo:rerun-if-changed=src/main.rs"); // <- 4
}

rust
use marine_rs_sdk_test::generate_marine_test_env;
use marine_rs_sdk_test::ServiceDescription;
fn main() {
    let services = vec![ // <- 1
        ("greeting".to_string(), ServiceDescription {
            config_path: "Config.toml".to_string(),
            modules_dir: Some("artifacts".to_string()),
        })
    ];
    let target = std::env::var("CARGO_CFG_TARGET_ARCH").unwrap();
    if target != "wasm32" { // <- 2
        generate_marine_test_env(services, "marine_test_env.rs", file!()); // <- 3
    }
    println!("cargo:rerun-if-changed=src/main.rs"); // <- 4
}

src/main.rs

rust
use marine_rs_sdk::marine;
use marine_rs_sdk::module_manifest;
module_manifest!();
pub fn main() {}
#[marine]
pub fn greeting(name: String) -> String {
    format!("Hi, {}", name)
}
#[cfg(test)]
mod built_tests {
    marine_rs_sdk_test::include_test_env!("/marine_test_env.rs"); // <- 4
    #[test]
    fn non_empty_string() {
        let mut greeting = marine_test_env::greeting::ServiceInterface::new();
        let actual = greeting.greeting("name".to_string());
        assert_eq!(actual, "Hi, name");
    }
}t

rust
use marine_rs_sdk::marine;
use marine_rs_sdk::module_manifest;
module_manifest!();
pub fn main() {}
#[marine]
pub fn greeting(name: String) -> String {
    format!("Hi, {}", name)
}
#[cfg(test)]
mod built_tests {
    marine_rs_sdk_test::include_test_env!("/marine_test_env.rs"); // <- 4
    #[test]
    fn non_empty_string() {
        let mut greeting = marine_test_env::greeting::ServiceInterface::new();
        let actual = greeting.greeting("name".to_string());
        assert_eq!(actual, "Hi, name");
    }
}t

Cargo.toml

toml
[package]
name = "wasm-build-rs"
version = "0.1.0"
authors = ["Fluence Labs"]
description = "The greeting module for the Fluence network"
repository = "https://github.com/fluencelabs/marine/tree/master/examples/build_rs"
edition = "2018"
publish = false
[[bin]]
name = "build_rs_test"
path = "src/main.rs"
[dependencies]
marine-rs-sdk = "0.10.2"
[dev-dependencies]
marine-rs-sdk-test = "0.5.0"
[build-dependencies]
marine-rs-sdk-test = "0.5.0"

toml
[package]
name = "wasm-build-rs"
version = "0.1.0"
authors = ["Fluence Labs"]
description = "The greeting module for the Fluence network"
repository = "https://github.com/fluencelabs/marine/tree/master/examples/build_rs"
edition = "2018"
publish = false
[[bin]]
name = "build_rs_test"
path = "src/main.rs"
[dependencies]
marine-rs-sdk = "0.10.2"
[dev-dependencies]
marine-rs-sdk-test = "0.5.0"
[build-dependencies]
marine-rs-sdk-test = "0.5.0"

1. We create a vector of pairs (service_name, service_description) to pass to the generator. The structure is the same with multi-service marine_test.
2. We check if we build for a non-wasm target. As we build this marine service only for wasm32-wasi and tests are built for native target, we can generate marine_test_env only for tests. This is needed because our generator depends on the artifacts from wasm32-wasi build. We suggest using a separate crate for using build scripts for testing purposes. It is here for simplicity.
3. We pass our services, the name of the file to generate, and a path to the build script file to the marine_test_env generator. Just always use file!() for the last argument. The generated file will be in the directory specified by the OUT_DIR variable, which is set by cargo. The build script must not change any files outside of this directory.
4. We set up conditions to re-run the build script. It must be customized, a good choice is to re-run the build script when .wasm files or Config.toml are changed.
5. We import the generated file with the marine_test_env definition to the project.
6. Do not forget to add marine-rs-sdk-test to the build-dependencies section of Cargo.toml.