spin_dependency_wit/

lib.rs

use std::path::Path;

use anyhow::Context;
use spin_loader::WasmLoader;
use spin_manifest::schema::v2::ComponentDependency;
use spin_serde::DependencyName;
use wit_component::DecodedWasm;
use wit_parser::Span;

const GENERATED_COMMENT: &str = "// This file is automatically generated by Spin\n// It is not intended for manual editing.\n\n";

/// The exports and middleware status of a Wasm component, decoded once.
///
/// Decoding a component's WIT is relatively expensive, so callers that need both
/// its exports and whether it is middleware should build a single
/// `ComponentInterfaces` and reuse it rather than re-inspecting the raw bytes.
pub struct ComponentInterfaces {
    exports: Vec<String>,
    is_http_middleware: bool,
}

impl ComponentInterfaces {
    /// Decode a Wasm component and inspect its world's imports and exports.
    pub fn from_component(wasm_bytes: &[u8]) -> anyhow::Result<Self> {
        let decoded = read_wasm(wasm_bytes)?;
        let (resolve, world_id) = match &decoded {
            DecodedWasm::WitPackage(resolve, pkg_id) => {
                let world_id = resolve.select_world(&[*pkg_id], None)?;
                (resolve, world_id)
            }
            DecodedWasm::Component(resolve, world_id) => (resolve, *world_id),
        };

        let world = resolve
            .worlds
            .get(world_id)
            .context("world not found in decoded Wasm")?;

        let exports = world
            .exports
            .keys()
            .filter_map(|key| format_world_key(resolve, key))
            .collect();

        // Middleware both imports and exports `wasi:http/handler`: the export
        // receives the request; the import forwards it to the next component in
        // the pipeline. A regular HTTP handler only exports `handler`.
        let is_http_middleware = contains_wasi_http_handler(resolve, world.imports.keys())
            && contains_wasi_http_handler(resolve, world.exports.keys());

        Ok(Self {
            exports,
            is_http_middleware,
        })
    }

    /// Whether the component is HTTP middleware.
    pub fn is_http_middleware(&self) -> bool {
        self.is_http_middleware
    }

    /// The component's exports, formatted as dependency-name strings.
    ///
    /// Interface exports from a package are formatted as
    /// `namespace:package/interface@version`. Exports declared with a bare name
    /// (for example an exported function, or an inline interface) are returned as
    /// that plain kebab-case name.
    pub fn exports(&self) -> &[String] {
        &self.exports
    }
}

/// Format a world key as a dependency-name string, returning `None` for
/// interface exports that lack package information.
fn format_world_key(resolve: &wit_parser::Resolve, key: &wit_parser::WorldKey) -> Option<String> {
    match key {
        wit_parser::WorldKey::Name(name) => Some(name.clone()),
        wit_parser::WorldKey::Interface(iface_id) => {
            let iface = resolve.interfaces.get(*iface_id)?;
            let pkg = resolve.packages.get(iface.package?)?;
            let ns = &pkg.name.namespace;
            let name = &pkg.name.name;
            let iface_name = iface.name.as_deref().unwrap_or("unknown");
            Some(match &pkg.name.version {
                Some(version) => format!("{ns}:{name}/{iface_name}@{version}"),
                None => format!("{ns}:{name}/{iface_name}"),
            })
        }
    }
}

fn contains_wasi_http_handler<'a>(
    resolve: &wit_parser::Resolve,
    keys: impl Iterator<Item = &'a wit_parser::WorldKey>,
) -> bool {
    keys.filter_map(|key| match key {
        wit_parser::WorldKey::Interface(id) => resolve.interfaces.get(*id),
        wit_parser::WorldKey::Name(_) => None,
    })
    .any(|iface| {
        let Some(pkg_id) = iface.package else {
            return false;
        };
        let Some(pkg) = resolve.packages.get(pkg_id) else {
            return false;
        };
        pkg.name.namespace == "wasi"
            && pkg.name.name == "http"
            && iface.name.as_deref() == Some("handler")
    })
}

pub async fn extract_wits_into(
    source: impl ExactSizeIterator<Item = (&DependencyName, &ComponentDependency)>,
    app_root: impl AsRef<Path>,
    dest_file: impl AsRef<Path>,
) -> anyhow::Result<()> {
    if source.len() == 0 {
        if dest_file.as_ref().is_file() {
            _ = tokio::fs::remove_file(dest_file).await; // Not an error if tidying fails
        }
        return Ok(());
    }

    let wit_text = format!(
        "{}{}",
        GENERATED_COMMENT,
        extract_wits(source, app_root).await?
    );

    tokio::fs::create_dir_all(
        dest_file
            .as_ref()
            .parent()
            .context("file is root directory")?,
    )
    .await?;
    tokio::fs::write(dest_file, wit_text.as_bytes()).await?;

    Ok(())
}

enum ImportKind {
    Function(spin_serde::KebabId),
    WholePackage,
    Interface(spin_serde::KebabId),
}

pub async fn extract_wits(
    source: impl Iterator<Item = (&DependencyName, &ComponentDependency)>,
    app_root: impl AsRef<Path>,
) -> anyhow::Result<String> {
    let loader = WasmLoader::new(app_root.as_ref().to_owned(), None, None).await?;

    let mut package_wits = indexmap::IndexMap::new();

    let mut aggregating_resolve = wit_parser::Resolve::default();
    let aggregating_pkg_id =
        aggregating_resolve.push_str("dummy.wit", "package root:component;\n\nworld root {}")?;
    let aggregating_world_id =
        aggregating_resolve.select_world(&[aggregating_pkg_id], Some("root"))?;

    // TODO: figure out what to do if we import two itfs from same dep
    for (index, (dependency_name, dependency)) in source.enumerate() {
        let import_kind = match dependency_name {
            DependencyName::Plain(name) => ImportKind::Function(name.clone()),
            DependencyName::Package(dependency_package_name) => {
                match &dependency_package_name.interface {
                    Some(itf) => ImportKind::Interface(itf.clone()),
                    None => ImportKind::WholePackage,
                }
            }
        };

        let (wasm_path, export) = loader
            .load_dependency_content(dependency_name, dependency)
            .await
            .with_context(|| format!("failed to load dependency {dependency_name}"))?;
        let wasm_bytes = tokio::fs::read(&wasm_path).await?;

        let decoded = read_wasm(&wasm_bytes)?;
        let decoded = match export {
            None => decoded,
            Some(export) => {
                munge_aliased_export(decoded, &export, dependency_name).with_context(|| {
                    format!("failed to map named export {export} to dependency {dependency_name}")
                })?
            }
        };
        let impo_world = format!("impo-world{index}");
        let importised = importize(decoded, Some(&impo_world))
            .with_context(|| format!("failed to map importize dependency {dependency_name}"))?;

        let imports = match &import_kind {
            ImportKind::WholePackage => all_imports(&importised),
            ImportKind::Interface(itf) => one_import(&importised, itf.as_ref())?,
            ImportKind::Function(_) => Default::default(),
        };
        let func_import = match &import_kind {
            ImportKind::Function(f) => one_func_import(&importised, f.as_ref())?,
            _ => Default::default(),
        };
        let type_imports = match &import_kind {
            ImportKind::Function(_) => world_type_imports(&importised),
            _ => Default::default(),
        };

        // Capture WITs for all packages used in the importised thing.
        // Things like WASI packages may be depended on by multiple packages
        // so we index on the package name to avoid emitting them twice.

        let root_pkg = importised.package();
        let useful_pkgs = importised
            .resolve()
            .packages
            .iter()
            .map(|p| p.0)
            .filter(|pid| *pid != root_pkg)
            .collect::<Vec<_>>();

        for p in &useful_pkgs {
            let pkg_name = importised
                .resolve()
                .packages
                .get(*p)
                .context("package not found in importised (id lookup failed)")? // shouldn't happen
                .name
                .clone();
            let output = wit_component::OutputToString::default();
            let mut printer = wit_component::WitPrinter::new(output);
            printer.print_package(importised.resolve(), *p, false)?;
            package_wits.insert(pkg_name, printer.output.to_string());
        }

        // Now add the imports to the aggregating component import world

        let remap = aggregating_resolve.merge(importised.resolve().clone())?;
        for iid in imports {
            let mapped_iid = remap.map_interface(iid, Span::default())?;
            let wk = wit_parser::WorldKey::Interface(mapped_iid);
            let world_item = wit_parser::WorldItem::Interface {
                id: mapped_iid,
                stability: wit_parser::Stability::Unknown,
                span: Span::default(),
                docs: Default::default(),
                external_id: None,
            };
            let previous_world_item = aggregating_resolve
                .worlds
                .get_mut(aggregating_world_id)
                .context("aggregated dependency world doesn't exist")? // shouldn't happen
                .imports
                .insert(wk, world_item);
            if let Some(previous_world_item) = previous_world_item {
                debug_assert!({
                    let wit_parser::WorldItem::Interface { id, .. } = previous_world_item else {
                        debug_assert!(
                            false,
                            "previous WorldItem did not match inserted WorldItem: not an interface"
                        );
                        break;
                    };
                    debug_assert_eq!(
                        id, mapped_iid,
                        "replacing WorldItem had a different InterfaceId from replaced one"
                    );

                    true
                });
            }
        }
        if let Some(mut func) = func_import {
            // Remap type IDs in the function to reference the aggregating resolve
            for param in &mut func.params {
                if let wit_parser::Type::Id(id) = &mut param.ty {
                    *id = remap.map_type(*id, Span::default())?;
                }
            }
            if let Some(wit_parser::Type::Id(id)) = &mut func.result {
                *id = remap.map_type(*id, Span::default())?;
            }

            // Add world-level type definitions that the function depends on
            let aggregating_world = aggregating_resolve
                .worlds
                .get_mut(aggregating_world_id)
                .context("aggregated dependency world doesn't exist")?;
            for (name, type_id) in &type_imports {
                let mapped_id = remap.map_type(*type_id, Span::default())?;
                let wk = wit_parser::WorldKey::Name(name.clone());
                let world_item = wit_parser::WorldItem::Type {
                    id: mapped_id,
                    span: Span::default(),
                };
                aggregating_world.imports.insert(wk, world_item);
            }

            let wk = wit_parser::WorldKey::Name(func.name.clone());
            let world_item = wit_parser::WorldItem::Function(func);
            aggregating_world.imports.insert(wk, world_item);
        }
    }

    // Text for the root package and world(s)
    let world_output = wit_component::OutputToString::default();
    let mut world_printer = wit_component::WitPrinter::new(world_output);
    world_printer.print(&aggregating_resolve, aggregating_pkg_id, &[])?;

    let mut buf = String::new();

    // Print the root package and the world(s) with the imports
    buf.push_str(&world_printer.output.to_string());

    // Print each package
    for package_wit in package_wits.values() {
        buf.push_str(package_wit);
    }

    Ok(buf)
}

fn munge_aliased_export(
    decoded: DecodedWasm,
    export: &str,
    new_name: &DependencyName,
) -> anyhow::Result<DecodedWasm> {
    let export_qname = spin_serde::DependencyPackageName::try_from(export.to_string())?;
    let Some(export_itf_name) = export_qname.interface.as_ref() else {
        anyhow::bail!(
            "the export name should be a qualified interface name - {export_qname} doesn't specify interface"
        );
    };
    let export_pkg_name = wit_parser::PackageName {
        namespace: export_qname.package.namespace().to_string(),
        name: export_qname.package.name().to_string(),
        version: export_qname.version,
    };

    let DependencyName::Package(new_name) = new_name else {
        anyhow::bail!(
            "the dependency name should be a qualified interface name - {new_name} not qualified"
        );
    };
    let Some(new_itf_name) = new_name.interface.as_ref() else {
        anyhow::bail!(
            "the dependency name should be a qualified interface name - {new_name} doesn't specify an interface"
        );
    };
    let new_pkg_name = wit_parser::PackageName {
        namespace: new_name.package.namespace().to_string(),
        name: new_name.package.name().to_string(),
        version: new_name.version.clone(),
    };

    let (mut resolve, decode_id) = match decoded {
        DecodedWasm::WitPackage(resolve, id) => (resolve, WorldOrPackageId::Package(id)),
        DecodedWasm::Component(resolve, id) => (resolve, WorldOrPackageId::World(id)),
    };

    // Two scenarios:
    // 1. The new name is in a package that is already in the Resolve
    //    1a. The package already contains an interface with the right name
    //    1b. The package does not already contain an interface with the right name
    // 2. The new name is in a package that is NOT already in the Resolve

    let existing_pkg = resolve
        .packages
        .iter()
        .find(|(_pkg_id, pkg)| pkg.name == new_pkg_name);

    // We address the first level by creating the new-name package if it doesn't exist
    let (inserting_into_pkg_id, inserting_into_pkg) = match existing_pkg {
        Some(tuple) => tuple,
        None => {
            // insert the needed package
            let package_wit = format!("package {new_pkg_name};");
            let pkg_id = resolve
                .push_str(
                    std::env::current_dir().context("no current dir")?, // unused
                    &package_wit,
                )
                .with_context(|| format!("failed to create import alias package {new_pkg_name}"))?;
            let pkg = resolve
                .packages
                .get(pkg_id)
                .context("export alias package created but doesn't exist")?; // shouldn't happen
            (pkg_id, pkg)
        }
    };

    // Second level asks if the new-name package already contains the interface
    let existing_itf = inserting_into_pkg.interfaces.get(new_itf_name.as_ref());
    if existing_itf.is_some() {
        // This makes the questionable assumption that the matchingly interface already
        // in the package is the same as the export. E.g. given "a:b/i" = { export = "c:d/i" }
        // where the dep contains an `a:b` package with an interface named `i`, we will generate
        // from that rather than emitting the `c:d/i` WIT for `a:b/i`. We could be smarter about
        // this but we don't know if other things depend on `a:b/i` so replacing it could result
        // in a bad WIT. If this becomes a problem we could maybe try emitting it as something
        // like `a:b/i-from-c-d` but I'd prefer to cross that bridge when we come to it.
        return Ok(decode_id.make_decoded_wasm(resolve));
    }

    // The new-name package does not contain the interface: we need to slurp the EXPORTED itf into the `inserting_into`
    // package under the NEW (importing) interface name
    let Some(export_pkg_id) = resolve.package_names.get(&export_pkg_name) else {
        anyhow::bail!(
            "export is from a package ({}) that doesn't exist (name lookup failed)",
            export_pkg_name
        );
    };
    let Some(export_pkg) = resolve.packages.get(*export_pkg_id) else {
        anyhow::bail!(
            "export is from a package ({}) that doesn't exist (id lookup failed)",
            export_pkg_name
        );
    };
    let Some(export_itf_id) = export_pkg.interfaces.get(export_itf_name.as_ref()) else {
        anyhow::bail!(
            "export package ({}) doesn't contain interface {} (name lookup failed)",
            export_pkg_name,
            export_itf_name
        );
    };
    let Some(export_itf) = resolve.interfaces.get(*export_itf_id) else {
        anyhow::bail!(
            "export package ({}) doesn't contain interface {} (id lookup failed)",
            export_pkg_name,
            export_itf_name
        );
    };

    // Create the new-name interface by cloning the export interface
    let mut export_itf = export_itf.clone();
    export_itf.package = Some(inserting_into_pkg_id);
    export_itf.name = Some(new_itf_name.to_string());

    // Add the new-name interface to the resolve and to the new-name package
    let export_itf_id_new = resolve.interfaces.alloc(export_itf);
    let inserting_into_pkg_mut = resolve
        .packages
        .get_mut(inserting_into_pkg_id)
        .context("package id lookup that succeeded before failed now")?; // we re-lookup to get around a "mutable borrow at the same time as immutable borrow" woe
    inserting_into_pkg_mut
        .interfaces
        .insert(new_itf_name.to_string(), export_itf_id_new);

    let decoded = decode_id.make_decoded_wasm(resolve);

    Ok(decoded)
}

enum WorldOrPackageId {
    Package(wit_parser::PackageId),
    World(wit_parser::WorldId),
}

impl WorldOrPackageId {
    pub fn make_decoded_wasm(&self, resolve: wit_parser::Resolve) -> DecodedWasm {
        match self {
            Self::Package(id) => DecodedWasm::WitPackage(resolve, *id),
            Self::World(id) => DecodedWasm::Component(resolve, *id),
        }
    }
}

fn all_imports(wasm: &DecodedWasm) -> Vec<wit_parser::InterfaceId> {
    wasm.resolve()
        .worlds
        .iter()
        .flat_map(|(_wid, w)| w.imports.values())
        .flat_map(as_interface)
        .collect()
}

fn as_interface(wi: &wit_parser::WorldItem) -> Option<wit_parser::InterfaceId> {
    match wi {
        wit_parser::WorldItem::Interface { id, .. } => Some(*id),
        _ => None,
    }
}

fn as_func(wi: &wit_parser::WorldItem) -> Option<&wit_parser::Function> {
    match wi {
        wit_parser::WorldItem::Function(func) => Some(func),
        _ => None,
    }
}

fn one_import(wasm: &DecodedWasm, name: &str) -> anyhow::Result<Vec<wit_parser::InterfaceId>> {
    fn find_interface(
        resolve: &wit_parser::Resolve,
        iid: wit_parser::InterfaceId,
    ) -> Option<(wit_parser::InterfaceId, &wit_parser::Interface)> {
        resolve.interfaces.get(iid).map(|itf| (iid, itf))
    }

    let id = wasm
        .resolve()
        .worlds
        .iter()
        .flat_map(|(_wid, w)| w.imports.values())
        .flat_map(as_interface)
        .flat_map(|iid| find_interface(wasm.resolve(), iid))
        .find(|itf| itf.1.name.as_deref() == Some(name))
        .map(|t| t.0)
        .with_context(|| format!("interface {name} not found in component binary"))?;
    Ok(vec![id])
}

fn world_type_imports(wasm: &DecodedWasm) -> Vec<(String, wit_parser::TypeId)> {
    wasm.resolve()
        .worlds
        .iter()
        .flat_map(|(_wid, w)| {
            w.imports.iter().filter_map(|(wk, wi)| {
                if let wit_parser::WorldItem::Type { id, .. } = wi {
                    let name = match wk {
                        wit_parser::WorldKey::Name(n) => n.clone(),
                        wit_parser::WorldKey::Interface(_) => return None,
                    };
                    Some((name, *id))
                } else {
                    None
                }
            })
        })
        .collect()
}

fn one_func_import(wasm: &DecodedWasm, name: &str) -> anyhow::Result<Option<wit_parser::Function>> {
    let funcs = wasm
        .resolve()
        .worlds
        .iter()
        .flat_map(|w| {
            w.1.imports
                .iter()
                .flat_map(|(_wk, wi)| as_func(wi))
                .filter(|f| f.name == name)
        })
        .collect::<Vec<_>>();

    // This shouldn't happen because we are using the compiled Wasm so there should
    // be only one world in play.  But belt and braces.
    if funcs.len() > 1 {
        anyhow::bail!("Dependency exports more than one function named {name}");
    }
    Ok(funcs.first().cloned().cloned())
}

fn read_wasm(wasm_bytes: &[u8]) -> anyhow::Result<DecodedWasm> {
    if wasmparser::Parser::is_component(wasm_bytes) {
        wit_component::decode(wasm_bytes)
    } else {
        let (wasm, bindgen) = wit_component::metadata::decode(wasm_bytes)?;
        if wasm.is_none() {
            anyhow::bail!(
                "input is a core wasm module with no `component-type*` \
                    custom sections meaning that there is no WIT information; \
                    is the information not embedded or is this supposed \
                    to be a component?"
            )
        }
        Ok(DecodedWasm::Component(bindgen.resolve, bindgen.world))
    }
}

fn importize(decoded: DecodedWasm, out_world_name: Option<&String>) -> anyhow::Result<DecodedWasm> {
    let (mut resolve, world_id) = match decoded {
        DecodedWasm::Component(resolve, world) => (resolve, world),
        DecodedWasm::WitPackage(resolve, id) => {
            let world = resolve.select_world(&[id], None)?;
            (resolve, world)
        }
    };

    resolve
        .importize(world_id, out_world_name.cloned())
        .context("failed to move world exports to imports")?;

    Ok(DecodedWasm::Component(resolve, world_id))
}

#[cfg(test)]
mod test {
    use super::*;

    fn parse_wit(wit: &str) -> anyhow::Result<wit_parser::Resolve> {
        let mut resolve = wit_parser::Resolve::new();
        resolve.push_str("dummy.wit", wit)?;
        Ok(resolve)
    }

    fn generate_dummy_component(wit: &str, world: &str) -> Vec<u8> {
        generate_dummy_component_dep_has_imports(wit, world, &[])
    }

    fn generate_dummy_component_dep_has_imports(
        wit: &str,
        world: &str,
        dep_imports_wits: &[&str],
    ) -> Vec<u8> {
        let mut resolve = wit_parser::Resolve::default();
        for (index, dep_import_wit) in dep_imports_wits.iter().enumerate() {
            resolve
                .push_str(format!("test{index}"), dep_import_wit)
                .expect("should parse dep import WIT");
        }
        let package_id = resolve.push_str("test", wit).expect("should parse WIT");
        let world_id = resolve
            .select_world(&[package_id], Some(world))
            .expect("should select world");

        let mut wasm = wit_component::dummy_module(
            &resolve,
            world_id,
            wit_parser::ManglingAndAbi::Legacy(wit_parser::LiftLowerAbi::Sync),
        );
        wit_component::embed_component_metadata(
            &mut wasm,
            &resolve,
            world_id,
            wit_component::StringEncoding::UTF8,
            false,
        )
        .expect("should embed component metadata");

        wit_component::ComponentEncoder::default()
            .validate(true)
            .module(&wasm)
            .expect("should set module")
            .encode()
            .expect("should encode component")
    }

    #[tokio::test]
    async fn if_no_dependencies_then_empty_valid_wit() -> anyhow::Result<()> {
        let wit = extract_wits(std::iter::empty(), ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        assert_eq!(1, resolve.packages.len());
        assert_eq!(
            "root:component",
            resolve.packages.iter().next().unwrap().1.name.to_string()
        );

        assert_eq!(0, resolve.interfaces.len());

        assert_eq!(1, resolve.worlds.len());

        let world = resolve.worlds.iter().next().unwrap().1;
        assert_eq!("root", world.name);
        assert_eq!(0, world.imports.len());

        Ok(())
    }

    #[tokio::test]
    async fn single_dep_wit_extracted() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("regex.wasm");

        let dep_wit = "package my:regex@1.0.0;\n\ninterface regex {\n  matches: func(s: string) -> bool;\n}\nworld matcher {\n  export regex;\n}";
        let dep_wasm = generate_dummy_component(dep_wit, "matcher");
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name =
            DependencyName::Package("my:regex/regex@1.0.0".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        assert_eq!(2, resolve.packages.len()); // root:component and my:regex
        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");
        let (_mr_pkg_id, _mr_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "my:regex@1.0.0")
            .expect("should have had `my:regex`");

        assert_eq!(1, resolve.interfaces.len());
        assert_eq!(
            "regex",
            resolve
                .interfaces
                .iter()
                .next()
                .unwrap()
                .1
                .name
                .as_ref()
                .unwrap()
        );
        let regex_itf_id = resolve.interfaces.iter().next().unwrap().0;

        assert_eq!(2, rc_pkg.worlds.len()); // root and synthetic "impo*" wart
        let root_world_id = rc_pkg
            .worlds
            .iter()
            .find(|w| w.0 == "root")
            .expect("should have had `root` world")
            .1;

        let world = resolve.worlds.get(*root_world_id).unwrap();
        assert_eq!(1, world.imports.len());
        let expected_import = wit_parser::WorldItem::Interface {
            id: regex_itf_id,
            stability: wit_parser::Stability::Unknown,
            span: Span::default(),
            docs: Default::default(),
            external_id: None,
        };
        let import = world.imports.values().next().unwrap();
        assert_eq!(&expected_import, import);

        Ok(())
    }

    #[tokio::test]
    async fn world_level_func_extracted() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("crimes.wasm");

        let dep_wit = "package my:crimes@1.0.0;\n\nworld crimes {\n  export is-curse: func(s: string) -> bool;\n}";
        let dep_wasm = generate_dummy_component(dep_wit, "crimes");
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name = DependencyName::Plain("is-curse".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        assert_eq!(1, resolve.packages.len()); // root:component - world-level funcs don't retain their package when importised
        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");

        let root_world_id = rc_pkg
            .worlds
            .get("root")
            .expect("should have had root world");
        let root_world = resolve
            .worlds
            .get(*root_world_id)
            .expect("should have had root world at that id");

        let func = root_world
            .imports
            .iter()
            .filter_map(|(_, wi)| as_func(wi))
            .find(|f| f.name == "is-curse")
            .expect("is-curse function does not appear in root imports");

        assert_eq!(1, func.params.len());
        assert_eq!(wit_parser::Type::String, func.params.first().unwrap().ty);
        assert_eq!(wit_parser::Type::Bool, func.result.unwrap());

        Ok(())
    }

    #[tokio::test]
    async fn world_level_func_with_record_param() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("greeter.wasm");

        let dep_wit = r#"package my:greeter@1.0.0;

world greeter {
  record person {
    name: string,
    age: u32,
  }
  export greet: func(who: person) -> string;
}"#;
        let dep_wasm = generate_dummy_component(dep_wit, "greeter");
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name = DependencyName::Plain("greet".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");

        let root_world_id = rc_pkg
            .worlds
            .get("root")
            .expect("should have had root world");
        let root_world = resolve
            .worlds
            .get(*root_world_id)
            .expect("should have had root world at that id");

        let func = root_world
            .imports
            .iter()
            .filter_map(|(_, wi)| as_func(wi))
            .find(|f| f.name == "greet")
            .expect("greet function does not appear in root imports");

        assert_eq!(1, func.params.len());
        // The param should be a user-defined type (record)
        assert!(
            matches!(func.params.first().unwrap().ty, wit_parser::Type::Id(_)),
            "expected record param to be Type::Id"
        );
        assert_eq!(wit_parser::Type::String, func.result.unwrap());

        Ok(())
    }

    #[tokio::test]
    async fn world_level_func_with_record_result() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("lookup.wasm");

        let dep_wit = r#"package my:lookup@1.0.0;

world lookup {
  record info {
    value: string,
    found: bool,
  }
  export lookup: func(key: string) -> info;
}"#;
        let dep_wasm = generate_dummy_component(dep_wit, "lookup");
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name = DependencyName::Plain("lookup".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");

        let root_world_id = rc_pkg
            .worlds
            .get("root")
            .expect("should have had root world");
        let root_world = resolve
            .worlds
            .get(*root_world_id)
            .expect("should have had root world at that id");

        let func = root_world
            .imports
            .iter()
            .filter_map(|(_, wi)| as_func(wi))
            .find(|f| f.name == "lookup")
            .expect("lookup function does not appear in root imports");

        assert_eq!(1, func.params.len());
        assert_eq!(wit_parser::Type::String, func.params.first().unwrap().ty);
        // The result should be a user-defined type (record)
        assert!(
            matches!(func.result, Some(wit_parser::Type::Id(_))),
            "expected record result to be Type::Id"
        );

        Ok(())
    }

    #[tokio::test]
    async fn world_level_func_with_enum_param() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("color.wasm");

        let dep_wit = r#"package my:colors@1.0.0;

world colors {
  enum color {
    red,
    green,
    blue,
  }
  export color-name: func(c: color) -> string;
}"#;
        let dep_wasm = generate_dummy_component(dep_wit, "colors");
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name = DependencyName::Plain("color-name".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");

        let root_world_id = rc_pkg
            .worlds
            .get("root")
            .expect("should have had root world");
        let root_world = resolve
            .worlds
            .get(*root_world_id)
            .expect("should have had root world at that id");

        let func = root_world
            .imports
            .iter()
            .filter_map(|(_, wi)| as_func(wi))
            .find(|f| f.name == "color-name")
            .expect("color-name function does not appear in root imports");

        assert_eq!(1, func.params.len());
        assert!(
            matches!(func.params.first().unwrap().ty, wit_parser::Type::Id(_)),
            "expected enum param to be Type::Id"
        );
        assert_eq!(wit_parser::Type::String, func.result.unwrap());

        Ok(())
    }

    #[tokio::test]
    async fn we_do_not_mix_up_dep_exports_with_same_named_dep_imports() -> anyhow::Result<()> {
        let tempdir = tempfile::TempDir::new()?;
        let dep_file = tempdir.path().join("impexp.wasm");

        let dep_wit = r#"
            package my:impexp@1.0.0;

            interface zounds {
                fie: func() -> bool;
            }

            world tester {
                export zounds;
                import clever:clogs/zounds@1.2.3;
            }"#;

        let dep_imports_another_zounds = r#"
            package clever:clogs@1.2.3;

            interface zounds {
                pshaw: func() -> u32;
            }
        "#;

        let dep_wasm = generate_dummy_component_dep_has_imports(
            dep_wit,
            "tester",
            &[dep_imports_another_zounds],
        );
        tokio::fs::write(&dep_file, &dep_wasm).await?;

        let dep_name =
            DependencyName::Package("my:impexp/zounds@1.0.0".to_string().try_into().unwrap());
        let dep_src = ComponentDependency::Local {
            path: dep_file,
            export: None,
            inherit_configuration: None,
        };
        let deps = std::iter::once((&dep_name, &dep_src));

        let wit = extract_wits(deps, ".").await?;

        let resolve = parse_wit(&wit).expect("should have emitted valid WIT");

        assert_eq!(3, resolve.packages.len()); // root:component and my:regex
        let (_rc_pkg_id, rc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "root:component")
            .expect("should have had `root:component`");
        let (_mi_pkg_id, _mi_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "my:impexp@1.0.0")
            .expect("should have had `my:impexp`");
        let (_cc_pkg_id, _cc_pkg) = resolve
            .packages
            .iter()
            .find(|(_, p)| p.name.to_string() == "clever:clogs@1.2.3")
            .expect("should have had `clever:clogs`");

        assert_eq!(2, rc_pkg.worlds.len()); // root and synthetic "impo*" wart
        let root_world_id = rc_pkg
            .worlds
            .iter()
            .find(|w| w.0 == "root")
            .expect("should have had `root` world")
            .1;

        let world = resolve.worlds.get(*root_world_id).unwrap();
        assert_eq!(1, world.imports.len());
        let (_, the_import) = world.imports.iter().next().unwrap();
        let the_import = as_interface(the_import).expect("the import was not an interface");
        let the_import_itf = resolve
            .interfaces
            .get(the_import)
            .expect("the import id failed at get");
        assert_eq!("zounds", the_import_itf.name.as_ref().unwrap());
        let the_import_pkg = resolve
            .packages
            .get(the_import_itf.package.unwrap())
            .expect("the import package failed at get");
        assert_eq!("my", the_import_pkg.name.namespace);
        assert_eq!("impexp", the_import_pkg.name.name);

        Ok(())
    }
}