An interactive CLI tool for building and testing XLS-102 WASM modules for the XRP Ledger.

• Installation
• Update detection
• Requirements
• Quick start
• Command reference
• Project Structure
• Managing rippled
• Running the XRPL Explorer
• Troubleshooting

Run from the repository root:

cargo install --path craft

• This installs the craft binary built from the local source in ./craft
• To update to the latest local changes, re-run the same command

When craft starts, it detects if the installed binary is stale compared to your local source:

• Compares the binary's build commit to your Git HEAD
• Detects uncommitted changes (dirty working tree)
• Falls back to file timestamps if Git metadata isn't available

If an update is recommended, craft prints a clear message and offers to run:

cargo install --path craft

To disable the check (e.g., in CI), set:

export CRAFT_DISABLE_UPDATE_CHECK=1

• Rust
• Cargo (with rustup)
• Docker (recommended for running rippled; optional if you build rippled locally)
• Optional: wasm-opt (Binaryen) for optimized WASM output
  • macOS: brew install binaryen
  • Linux (Debian/Ubuntu): sudo apt-get install -y binaryen

Docker is recommended to run the rippled server. Alternatively, you can build and run rippled locally by following the BUILD instructions in the rippled repository.

• macOS: https://docs.docker.com/desktop/install/mac-install/
• Windows: https://docs.docker.com/desktop/install/windows-install/
• Linux: https://docs.docker.com/engine/install/

After installation, ensure Docker is running before using rippled-related commands.

Common examples:

# Interactive menu (TTY only)
craft

# Build a project (defaults to release mode for WASM)
craft build <project-name>
craft build <project-name> --debug --opt none --fmt

# Test a WASM library function
craft test <project-name> --case success --function finish
craft test <project-name> --all --verbose

# Deploy to WASM Devnet
craft deploy <project-name>
craft deploy path/to/module.wasm --no-build

# Manage rippled (Docker)
craft start-rippled --foreground
craft list-rippled
craft advance-ledger --count 5
craft stop-rippled

# Open the XRPL Explorer in a browser
craft open-explorer

• build

  • Usage: craft build [project] [--debug] [--opt <none|small|aggressive>] [--fmt] [--env KEY=VALUE ...] [-- <cargo-args>...]
  • Defaults: release mode; --opt small
  • Behavior: if no project and running in a TTY, an interactive selector is shown

• test

  • Usage: craft test [project] [--case <name> | --all] [--function <name>] [--build/--no-build] [--verbose] [--list]
  • Defaults: case = success; function = finish; --build is on by default
  • --list prints available test cases (optionally for a specific project) and exits

• deploy

  • Usage: craft deploy <target> [--no-build] [--env KEY=VALUE ...]
  • Target: either a project name under projects/ or a path to a .wasm file

• list

  • Usage: craft list <projects|tests|fixtures>

• configure

  • Interactive setup for preferred build/test settings used by other commands

• export-hex

  • Builds the current selection and copies the WASM hex to your clipboard

• rippled management (Docker)

  • craft start-rippled [--foreground]
  • craft list-rippled
  • craft stop-rippled
  • craft advance-ledger [--count <n>]

• open-explorer

  • craft open-explorer opens the XRPL Explorer in your default browser

Organize your WASM modules in the projects directory:

.
├── projects/
│   └── helloworld/      # Example
│       ├── Cargo.toml
│       └── src/
│           └── lib.rs
└── ...

The tool automatically discovers WASM projects under projects/ (including nested subprojects).

This tool provides a testing environment for XLS-100 compliant WebAssembly modules. It simulates the host environment that will execute escrow finish conditions on the XRPL.

For details on the WASM VM integration, see XLS-102: WASM VM Configuration.

The wasm-host-simulator tool:

1. Loads and executes WebAssembly modules
2. Provides test transaction and ledger object data
3. Calls the finish function as specified in XLS-100
4. Reports execution results and any errors

Test fixtures must be placed in projects/<project>/fixtures/<test_case>/

This convention co-locates each project's test data with its source code, making projects self-contained.

Each test case directory can contain:

• tx.json: Transaction data
• ledger_object.json: Current ledger object being tested
• ledger_header.json: Ledger header information
• ledger.json: Full ledger data
• nfts.json: NFT data (if applicable)

The notary project includes test fixtures for validating escrow finish conditions:

• Success Case (projects/notary/fixtures/success/): Tests when the escrow finish condition is met (transaction with the correct notary account)
• Failure Case (projects/notary/fixtures/failure/): Tests when the escrow finish condition is not met (transaction with an incorrect notary account)

The host_functions_test project includes fixtures for testing various host function capabilities. This project can be found in:

rippled-tests/host_functions_test/

• Success Case (rippled-tests/host_functions_test/fixtures/success/): Tests successful execution of 26 host functions

To clone this repository, use:

git clone git@github.com:ripple/craft.git

The craft tool uses Docker to manage a rippled instance.

Ensure Docker Desktop is installed and running. Then manage rippled using these commands:

craft start-rippled                 # Start rippled container (background mode)
craft start-rippled --foreground    # Start with visible console output
craft list-rippled                  # List running rippled containers
craft stop-rippled                  # Stop the rippled container

The tool uses the Docker image legleux/rippled_smart_escrow:bb9bb5f5 which includes support for smart escrows.

Note: Ensure Docker is installed and running before using craft start-rippled.

You can also manage the container directly with Docker:

# View logs
docker logs -f craft-rippled

# Stop container
docker stop craft-rippled

# Remove container
docker rm craft-rippled

• Public WebSocket: ws://localhost:6005
• Admin WebSocket: ws://localhost:6006
• Admin RPC API: http://localhost:5005

The craft tool includes commands to open the XRPL Explorer:

# Open the Explorer
craft open-explorer

From the wasm-host-simulator directory:

# Run with success test case
cargo run -- --dir path/to/your/project_name --test-case success

# Run with failure test case
cargo run -- --dir path/to/your/project_name --test-case failure

From any workspace directory:

cargo run -p wasm-host-simulator -- --dir path/to/your/project_name --test-case success --project <project_name>

• --dir <PATH>: Path to the source code where fixtures are located
• --test-case <CASE>: Test case to run (defaults to success)
• --project <NAME>: Project name (required)
• --verbose: Enable detailed logging
• -h, --help: Show help information

To see detailed execution information, including memory allocation, data processing, and function execution steps, use the --verbose flag:

cargo run -p wasm-host-simulator --dir path/to/folder --project project --test-case success --verbose

The verbose output may include:

• Memory allocation details
• JSON data being processed
• Function execution steps
• Results of the execution

Example verbose output:

[INFO wasm_host_simulator] Starting Wasm host application
[INFO wasm_host_simulator] Loading WASM module from: path/to/module.wasm
[INFO wasm_host_simulator] Target function: finish (XLS-100d)
[INFO wasm_host_simulator] Using test case: success
[DEBUG wasm_host_simulator] Initializing WasiModule
[DEBUG wasm_host_simulator] WasiModule initialized successfully
[INFO wasm_host_simulator::vm] Executing WASM function: finish
[DEBUG wasm_host_simulator::vm] TX data size: 610 bytes, LO data size: 919 bytes
[INFO wasm_host_simulator::vm] Allocating memory for transaction data
[DEBUG wasm_host_simulator::vm] Allocated memory at address: 0x110008
...

The wasm-host-simulator tool is typically used through the craft test command, which provides an interactive interface for selecting test cases:

# Test a WASM module
craft test

# Test with verbose output
RUST_LOG=debug craft test

The interactive interface will prompt you to select:

1. Test case (success/failure)
2. Other build and test options

The tool provides test data that simulates:

1. An EscrowFinish transaction
2. An Escrow ledger object

This data is used to test the module's finish function implementation.

To add new test cases to a project:

1. Create a new directory under projects/<project>/fixtures/<test_case>/
2. Add desired JSON files:
   • tx.json: Transaction data
   • ledger_object.json: Ledger object being tested
   • ledger_header.json: Ledger header information
   • ledger.json: Full ledger data
   • nfts.json: NFT data (if applicable)
3. Run the test using: craft test <project> --case <test_case>

If the WebAssembly module execution fails, the tool will:

1. Display an error message explaining the failure
2. Show the function name that failed
3. Show the test case being run
4. Provide context about the error
5. Exit with a non-zero status code

Example error output:

-------------------------------------------------
| WASM FUNCTION EXECUTION ERROR                 |
-------------------------------------------------
| Function:  finish                             |
| Test Case: failure                            |
| Error:     WASM function execution error      |
-------------------------------------------------

This repository contains multiple Rust crates. You can use rustdoc to generate and view documentation.

• Public crates only (recommended):
  • cargo doc --no-deps -p craft --target-dir target
  • cargo doc --no-deps -p xrpl-wasm-std --target-dir target
• Entire workspace:
  • cargo doc --workspace --no-deps
• Open docs in your browser:
  • cargo doc --no-deps --open

A helper script is included:

./build-docs.sh

This cleans previous docs, builds docs for craft and xrpl-wasm-std (into a shared target/ directory), runs doctests for xrpl-wasm-std, and prints the path to the rendered docs.

• After building, open: target/doc/index.html to see the docs index
• Direct links:
  • Craft CLI docs: target/doc/craft/index.html
  • xrpl-wasm-std library: target/doc/xrpl_wasm_std/index.html
• Or simply run: cargo doc --open

• Use //! for crate- and module-level documentation; use /// for items (functions, structs, enums)
• Prefer small, runnable examples. For examples that should not run in doctests, use code fences with language modifiers:
  • rust,no_run for examples that should compile but not execute
  • rust,ignore for examples that should not be compiled
• Use intra-doc links to reference items within a crate, e.g. [Result](core::result::Result)
• Test your docs: cargo test --doc (per-crate or workspace)
• Hide internal implementation details with #[doc(hidden)]
• Feature-gate docs for optional APIs with #[cfg_attr(doc_cfg, doc(cfg(feature = "...")))]

You can include standalone Markdown files directly into your crate documentation using include_str!:

• Include a crate README as the top-level docs (in src/lib.rs or src/main.rs):

#![doc = include_str!("../../README.md")]

• Include additional guides as modules shown in docs only:

/// Additional guides and how-tos
#[cfg(doc)]
pub mod guides {
    /// XRPL Field Access and Locators guide
    #[doc = include_str!("../../docs/FIELD_ACCESS.md")]
    pub mod field_access {}
}

In this repository:

• The xrpl-wasm-std crate already includes its README via #![doc = include_str!("../README.md")]
• The guide at docs/FIELD_ACCESS.md is included under the rendered docs at xrpl_wasm_std::guides::field_access

• Examples that reference unavailable items or host-only APIs are marked as rust,ignore to prevent doctest failures
• Prefer rust or rust,no_run for examples intended to compile

• Update prompt keeps appearing

  • Reinstall: cargo install --path craft
  • Ensure you are running craft from the repository root
  • To temporarily disable checks: export CRAFT_DISABLE_UPDATE_CHECK=1

• Docker not found or not running (macOS)

  • Install/start Colima: brew install colima docker && colima start
  • If using Docker Desktop, ensure it is running

• wasm-opt not found

  • Install Binaryen: macOS brew install binaryen, Linux sudo apt-get install -y binaryen