Add a new wit-smith subcommand (#992)

* Add a new `wit-smith` subcommand

This commit extracts the WIT document generation from the
`roundtrip-wit` fuzzer into a dedicated crate and a dedicated
subcommand, `wasm-tools wit-smith`. This is intended to behave similarly
to the `wasm-tools smith` subcommand but it instead generates a
WebAssembly binary-encoded WIT document.

* Fix build of wit-smith in isolation

.github/workflows/main.yml

@@ -89,6 +89,7 @@ jobs:
       - run: cargo check --no-default-features --features demangle
       - run: cargo check --no-default-features --features component
       - run: cargo check --no-default-features --features metadata
+      - run: cargo check --no-default-features --features wit-smith
 
   doc:
     runs-on: ubuntu-latest

Cargo.toml

@@ -54,6 +54,7 @@ wast = { version = "56.0.0", path = "crates/wast" }
 wat = { version = "1.0.62", path = "crates/wat" }
 wit-component = { version = "0.8.1", path = "crates/wit-component" }
 wit-parser = { version = "0.7.0", path = "crates/wit-parser" }
+wit-smith = { version = "0.1.0", path = "crates/wit-smith" }
 
 [dependencies]
 anyhow = { workspace = true }
@@ -103,6 +104,9 @@ wast = { workspace = true, optional = true }
 # Dependencies of `metadata`
 wasm-metadata = { workspace = true, features = ["clap"], optional = true }
 
+# Dependencies of `wit-smith`
+wit-smith = { workspace = true, features = ["clap"], optional = true }
+
 [dev-dependencies]
 serde_json = "1.0"
 tempfile = "3.1"
@@ -134,6 +138,7 @@ default = [
   'demangle',
   'component',
   'metadata',
+  'wit-smith',
 ]
 
 # Each subcommand is gated behind a feature and lists the dependencies it needs
@@ -150,3 +155,4 @@ compose = ['wasm-compose']
 demangle = ['rustc-demangle', 'cpp_demangle', 'wasmparser', 'wasm-encoder']
 component = ['wit-component', 'wit-parser', 'wast', 'wasm-encoder', 'wasmparser']
 metadata = ['wasmparser', 'wasm-metadata', 'serde_json' ]
+wit-smith = ['dep:wit-smith', 'arbitrary']

crates/wit-smith/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+description = "A WIT test case generator"
+documentation = "https://docs.rs/wit-smith"
+edition.workspace = true
+license = "Apache-2.0 WITH LLVM-exception"
+name = "wit-smith"
+repository = "https://github.com/bytecodealliance/wasm-tools/tree/main/crates/wit-smith"
+version = "0.1.0"
+
+[dependencies]
+arbitrary = { workspace = true, features = ["derive"] }
+wit-component = { workspace = true }
+wit-parser = { workspace = true }
+clap = { workspace = true, optional = true }

crates/wit-smith/src/config.rs

@@ -0,0 +1,48 @@
+use arbitrary::{Arbitrary, Result, Unstructured};
+
+#[derive(Debug, Clone)]
+#[cfg_attr(feature = "clap", derive(clap::Parser))]
+pub struct Config {
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_packages))]
+    pub max_packages: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_type_size))]
+    pub max_type_size: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_interface_items))]
+    pub max_interface_items: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_world_items))]
+    pub max_world_items: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_doc_items))]
+    pub max_doc_items: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_documents))]
+    pub max_documents: usize,
+    #[cfg_attr(feature = "clap", clap(long, default_value_t = Config::default().max_type_parts))]
+    pub max_type_parts: usize,
+}
+
+impl Default for Config {
+    fn default() -> Config {
+        Config {
+            max_packages: 10,
+            max_type_size: 100,
+            max_interface_items: 10,
+            max_world_items: 10,
+            max_doc_items: 10,
+            max_documents: 10,
+            max_type_parts: 10,
+        }
+    }
+}
+
+impl Arbitrary<'_> for Config {
+    fn arbitrary(u: &mut Unstructured<'_>) -> Result<Config> {
+        Ok(Config {
+            max_packages: u.int_in_range(1..=20)?,
+            max_documents: u.int_in_range(1..=10)?,
+            max_type_size: u.int_in_range(0..=1000)?,
+            max_interface_items: u.int_in_range(0..=20)?,
+            max_world_items: u.int_in_range(0..=10)?,
+            max_doc_items: u.int_in_range(0..=10)?,
+            max_type_parts: u.int_in_range(1..=10)?,
+        })
+    }
+}