src/sys/component_manager/src/model/resolver.rs - fuchsia - Git at Google

 // Copyright 2019 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 use {
     crate::{
         capability::EnvironmentCapability,
         model::{
             error::ModelError,
             realm::{Realm, WeakRealm},
             routing,
         },
     },
     anyhow::Error,
     clonable_error::ClonableError,
     cm_rust::{CapabilityName, RegistrationSource, ResolverRegistration},
     fidl_fuchsia_io as fio, fidl_fuchsia_sys2 as fsys,
     fuchsia_zircon::Status,
     futures::future::{self, BoxFuture},
     std::{collections::HashMap, sync::Arc},
     thiserror::Error,
     url::Url,
 };

 /// Resolves a component URL to its content.
 /// TODO: Consider defining an internal representation for `fsys::Component` so as to
 /// further isolate the `Model` from FIDL interfacting concerns.
 pub trait Resolver {
     fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a>;
 }

 pub type ResolverFut<'a> = BoxFuture<'a, Result<fsys::Component, ResolverError>>;

 #[derive(Error, Debug, Clone)]
 pub enum ResolverRegistrationError {
     #[error("a resolver is already registered with the URL scheme \"{}\"", 0)]
     SchemeAlreadyRegistered(String),
 }

 /// Resolves a component URL using a resolver selected based on the URL's scheme.
 #[derive(Default)]
 pub struct ResolverRegistry {
     resolvers: HashMap<String, Box<dyn Resolver + Send + Sync + 'static>>,
 }

 impl ResolverRegistry {
     pub fn new() -> ResolverRegistry {
         Default::default()
     }

     pub fn register(
         &mut self,
         scheme: String,
         resolver: Box<dyn Resolver + Send + Sync + 'static>,
     ) -> Result<(), ResolverRegistrationError> {
         if self.resolvers.contains_key(&scheme) {
             Err(ResolverRegistrationError::SchemeAlreadyRegistered(scheme.clone()))
         } else {
             self.resolvers.insert(scheme, resolver);
             Ok(())
         }
     }

     /// Creates and populates a `ResolverRegistry` with `RemoteResolvers` that
     /// have been registered with an environment.
     pub fn from_decl(
         decl: &[ResolverRegistration],
         parent: &Arc<Realm>,
     ) -> Result<Self, ResolverRegistrationError> {
         let mut registry = ResolverRegistry::new();
         for resolver in decl {
             registry.register(
                 resolver.scheme.clone().into(),
                 Box::new(RemoteResolver::new(
                     resolver.resolver.clone(),
                     resolver.source.clone(),
                     parent.as_weak(),
                 )),
             )?;
         }
         Ok(registry)
     }
 }

 impl Resolver for ResolverRegistry {
     fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
         match Url::parse(component_url) {
             Ok(parsed_url) => {
                 if let Some(ref resolver) = self.resolvers.get(parsed_url.scheme()) {
                     resolver.resolve(component_url)
                 } else {
                     Box::pin(future::err(ResolverError::SchemeNotRegistered))
                 }
             }
             Err(e) => Box::pin(future::err(ResolverError::url_parse_error(component_url, e))),
         }
     }
 }

 /// A resolver whose implementation lives in an external component. The source
 /// of the resolver is determined through capability routing.
 pub struct RemoteResolver {
     capability_name: CapabilityName,
     source: RegistrationSource,
     realm: WeakRealm,
 }

 impl RemoteResolver {
     pub fn new(name: CapabilityName, source: RegistrationSource, realm: WeakRealm) -> Self {
         RemoteResolver { capability_name: name, source, realm }
     }
 }

 // TODO(61288): Implement some sort of caching of the routed capability. Multiple
 // component URL resolutions should be possible on a single channel.
 impl Resolver for RemoteResolver {
     fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
         Box::pin(async move {
             let decl = EnvironmentCapability::Resolver {
                 source_name: self.capability_name.clone(),
                 source: self.source.clone(),
             };
             let flags = fio::OPEN_RIGHT_READABLE | fio::OPEN_RIGHT_WRITABLE;
             let open_mode = fio::MODE_TYPE_SERVICE;
             let (proxy, server_end) =
                 fidl::endpoints::create_proxy::<fsys::ComponentResolverMarker>()
                     .map_err(ResolverError::unknown_resolver_error)?;
             let realm = self.realm.upgrade().map_err(ResolverError::routing_error)?;
             routing::route_capability_from_environment(
                 flags,
                 open_mode,
                 String::new(),
                 decl,
                 &realm,
                 &mut server_end.into_channel(),
             )
             .await
             .map_err(ResolverError::routing_error)?;
             let (status, component) = proxy
                 .resolve(component_url)
                 .await
                 .map_err(ResolverError::unknown_resolver_error)?;
             let status = Status::from_raw(status);
             match status {
                 Status::OK => {
                     let decl = component.decl.as_ref().ok_or(ResolverError::RemoteInvalidData)?;
                     cm_fidl_validator::validate(decl)
                         .map_err(|e| ResolverError::manifest_invalid(component_url, e))?;
                     Ok(component)
                 }
                 Status::INVALID_ARGS => {
                     Err(ResolverError::url_parse_error(component_url, RemoteError(status)))
                 }
                 Status::NOT_FOUND => {
                     Err(ResolverError::component_not_available(component_url, RemoteError(status)))
                 }
                 Status::UNAVAILABLE => {
                     Err(ResolverError::manifest_invalid(component_url, RemoteError(status)))
                 }
                 _ => Err(ResolverError::unknown_resolver_error(RemoteError(status))),
             }
         })
     }
 }

 /// Errors produced by `Resolver`.
 #[derive(Debug, Error, Clone)]
 pub enum ResolverError {
     #[error("resolver is already registered for scheme \"{}\"", scheme)]
     DuplicateResolverError { scheme: String },
     #[error("component not available with url \"{}\": {}", url, err)]
     ComponentNotAvailable {
         url: String,
         #[source]
         err: ClonableError,
     },
     #[error("component manifest not available for url \"{}\": {}", url, err)]
     ManifestNotAvailable {
         url: String,
         #[source]
         err: ClonableError,
     },
     #[error("component manifest invalid for url \"{}\": {}", url, err)]
     ManifestInvalid {
         url: String,
         #[source]
         err: ClonableError,
     },
     #[error("Model not available.")]
     ModelAccessError,
     #[error("scheme not registered")]
     SchemeNotRegistered,
     #[error("failed to parse url \"{}\": {}", url, err)]
     UrlParseError {
         url: String,
         #[source]
         err: ClonableError,
     },
     #[error("url missing resource \"{}\"", url)]
     UrlMissingResourceError { url: String },
     #[error("failed to route resolver capability: {}", .0)]
     RoutingError(#[source] Box<ModelError>),
     #[error("the remote resolver returned invalid data")]
     RemoteInvalidData,
     #[error("an unknown error ocurred with the resolver: {}", .0)]
     UnknownResolverError(#[source] ClonableError),
 }

 impl ResolverError {
     pub fn component_not_available(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
         ResolverError::ComponentNotAvailable { url: url.into(), err: err.into().into() }
     }

     pub fn manifest_not_available(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
         ResolverError::ManifestNotAvailable { url: url.into(), err: err.into().into() }
     }

     pub fn manifest_invalid(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
         ResolverError::ManifestInvalid { url: url.into(), err: err.into().into() }
     }

     pub fn model_not_available() -> ResolverError {
         ResolverError::ModelAccessError
     }

     pub fn url_parse_error(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
         ResolverError::UrlParseError { url: url.into(), err: err.into().into() }
     }

     pub fn url_missing_resource_error(url: impl Into<String>) -> ResolverError {
         ResolverError::UrlMissingResourceError { url: url.into() }
     }

     pub fn routing_error(err: ModelError) -> ResolverError {
         ResolverError::RoutingError(Box::new(err))
     }

     pub fn unknown_resolver_error(err: impl Into<Error>) -> ResolverError {
         ResolverError::UnknownResolverError(err.into().into())
     }
 }

 #[derive(Error, Clone, Debug)]
 #[error("remote resolver returned status {}", .0)]
 struct RemoteError(Status);

 #[cfg(test)]
 mod tests {
     use {super::*, anyhow::format_err, matches::assert_matches};

     struct MockOkResolver {
         pub expected_url: String,
         pub resolved_url: String,
     }

     impl Resolver for MockOkResolver {
         fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
             assert_eq!(self.expected_url, component_url);
             Box::pin(future::ok(fsys::Component {
                 resolved_url: Some(self.resolved_url.clone()),
                 decl: Some(fsys::ComponentDecl {
                     program: None,
                     uses: None,
                     exposes: None,
                     offers: None,
                     facets: None,
                     capabilities: None,
                     children: None,
                     collections: None,
                     environments: None,
                     ..fsys::ComponentDecl::EMPTY
                 }),
                 package: None,
                 ..fsys::Component::EMPTY
             }))
         }
     }

     struct MockErrorResolver {
         pub expected_url: String,
         pub error: Box<dyn Fn(&str) -> ResolverError + Send + Sync + 'static>,
     }

     impl Resolver for MockErrorResolver {
         fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
             assert_eq!(self.expected_url, component_url);
             Box::pin(future::err((self.error)(component_url)))
         }
     }

     #[fuchsia_async::run_until_stalled(test)]
     async fn register_and_resolve() {
         let mut registry = ResolverRegistry::new();
         registry
             .register(
                 "foo".to_string(),
                 Box::new(MockOkResolver {
                     expected_url: "foo://url".to_string(),
                     resolved_url: "foo://resolved".to_string(),
                 }),
             )
             .unwrap();
         registry
             .register(
                 "bar".to_string(),
                 Box::new(MockErrorResolver {
                     expected_url: "bar://url".to_string(),
                     error: Box::new(|url| {
                         ResolverError::component_not_available(url, format_err!("not available"))
                     }),
                 }),
             )
             .unwrap();

         // Resolve known scheme that returns success.
         let component = registry.resolve("foo://url").await.unwrap();
         assert_eq!("foo://resolved", component.resolved_url.unwrap());

         // Resolve a different scheme that produces an error.
         let expected_res: Result<fsys::Component, ResolverError> =
             Err(ResolverError::component_not_available("bar://url", format_err!("not available")));
         assert_eq!(
             format!("{:?}", expected_res),
             format!("{:?}", registry.resolve("bar://url").await)
         );

         // Resolve an unknown scheme
         let expected_res: Result<fsys::Component, ResolverError> =
             Err(ResolverError::SchemeNotRegistered);
         assert_eq!(
             format!("{:?}", expected_res),
             format!("{:?}", registry.resolve("unknown://url").await),
         );

         // Resolve an URL lacking a scheme.
         let expected_res: Result<fsys::Component, ResolverError> =
             Err(ResolverError::url_parse_error("xxx", url::ParseError::RelativeUrlWithoutBase));
         assert_eq!(format!("{:?}", expected_res), format!("{:?}", registry.resolve("xxx").await),);
     }

     #[test]
     fn test_duplicate_registration() {
         let mut registry = ResolverRegistry::new();
         let resolver_a =
             MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
         let resolver_b =
             MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
         assert_matches!(registry.register("fuchsia-pkg".to_string(), Box::new(resolver_a)), Ok(()));
         assert_matches!(registry.register("fuchsia-pkg".to_string(), Box::new(resolver_b)), Err(ResolverRegistrationError::SchemeAlreadyRegistered(scheme)) if scheme == "fuchsia-pkg");
     }

     #[test]
     fn test_multiple_scheme_registration() {
         let mut registry = ResolverRegistry::new();
         let resolver_a =
             MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
         let resolver_b =
             MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
         registry.register("fuchsia-pkg".to_string(), Box::new(resolver_a)).unwrap();
         registry.register("fuchsia-boot".to_string(), Box::new(resolver_b)).unwrap();
     }
 }
	// Copyright 2019 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	use {
	crate::{
	capability::EnvironmentCapability,
	model::{
	error::ModelError,
	realm::{Realm, WeakRealm},
	routing,
	},
	},
	anyhow::Error,
	clonable_error::ClonableError,
	cm_rust::{CapabilityName, RegistrationSource, ResolverRegistration},
	fidl_fuchsia_io as fio, fidl_fuchsia_sys2 as fsys,
	fuchsia_zircon::Status,
	futures::future::{self, BoxFuture},
	std::{collections::HashMap, sync::Arc},
	thiserror::Error,
	url::Url,
	};

	/// Resolves a component URL to its content.
	/// TODO: Consider defining an internal representation for `fsys::Component` so as to
	/// further isolate the `Model` from FIDL interfacting concerns.
	pub trait Resolver {
	fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a>;
	}

	pub type ResolverFut<'a> = BoxFuture<'a, Result<fsys::Component, ResolverError>>;

	#[derive(Error, Debug, Clone)]
	pub enum ResolverRegistrationError {
	#[error("a resolver is already registered with the URL scheme \"{}\"", 0)]
	SchemeAlreadyRegistered(String),
	}

	/// Resolves a component URL using a resolver selected based on the URL's scheme.
	#[derive(Default)]
	pub struct ResolverRegistry {
	resolvers: HashMap<String, Box<dyn Resolver + Send + Sync + 'static>>,
	}

	impl ResolverRegistry {
	pub fn new() -> ResolverRegistry {
	Default::default()
	}

	pub fn register(
	&mut self,
	scheme: String,
	resolver: Box<dyn Resolver + Send + Sync + 'static>,
	) -> Result<(), ResolverRegistrationError> {
	if self.resolvers.contains_key(&scheme) {
	Err(ResolverRegistrationError::SchemeAlreadyRegistered(scheme.clone()))
	} else {
	self.resolvers.insert(scheme, resolver);
	Ok(())
	}
	}

	/// Creates and populates a `ResolverRegistry` with `RemoteResolvers` that
	/// have been registered with an environment.
	pub fn from_decl(
	decl: &[ResolverRegistration],
	parent: &Arc<Realm>,
	) -> Result<Self, ResolverRegistrationError> {
	let mut registry = ResolverRegistry::new();
	for resolver in decl {
	registry.register(
	resolver.scheme.clone().into(),
	Box::new(RemoteResolver::new(
	resolver.resolver.clone(),
	resolver.source.clone(),
	parent.as_weak(),
	)),
	)?;
	}
	Ok(registry)
	}
	}

	impl Resolver for ResolverRegistry {
	fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
	match Url::parse(component_url) {
	Ok(parsed_url) => {
	if let Some(ref resolver) = self.resolvers.get(parsed_url.scheme()) {
	resolver.resolve(component_url)
	} else {
	Box::pin(future::err(ResolverError::SchemeNotRegistered))
	}
	}
	Err(e) => Box::pin(future::err(ResolverError::url_parse_error(component_url, e))),
	}
	}
	}

	/// A resolver whose implementation lives in an external component. The source
	/// of the resolver is determined through capability routing.
	pub struct RemoteResolver {
	capability_name: CapabilityName,
	source: RegistrationSource,
	realm: WeakRealm,
	}

	impl RemoteResolver {
	pub fn new(name: CapabilityName, source: RegistrationSource, realm: WeakRealm) -> Self {
	RemoteResolver { capability_name: name, source, realm }
	}
	}

	// TODO(61288): Implement some sort of caching of the routed capability. Multiple
	// component URL resolutions should be possible on a single channel.
	impl Resolver for RemoteResolver {
	fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
	Box::pin(async move {
	let decl = EnvironmentCapability::Resolver {
	source_name: self.capability_name.clone(),
	source: self.source.clone(),
	};
	let flags = fio::OPEN_RIGHT_READABLE \| fio::OPEN_RIGHT_WRITABLE;
	let open_mode = fio::MODE_TYPE_SERVICE;
	let (proxy, server_end) =
	fidl::endpoints::create_proxy::<fsys::ComponentResolverMarker>()
	.map_err(ResolverError::unknown_resolver_error)?;
	let realm = self.realm.upgrade().map_err(ResolverError::routing_error)?;
	routing::route_capability_from_environment(
	flags,
	open_mode,
	String::new(),
	decl,
	&realm,
	&mut server_end.into_channel(),
	)
	.await
	.map_err(ResolverError::routing_error)?;
	let (status, component) = proxy
	.resolve(component_url)
	.await
	.map_err(ResolverError::unknown_resolver_error)?;
	let status = Status::from_raw(status);
	match status {
	Status::OK => {
	let decl = component.decl.as_ref().ok_or(ResolverError::RemoteInvalidData)?;
	cm_fidl_validator::validate(decl)
	.map_err(\|e\| ResolverError::manifest_invalid(component_url, e))?;
	Ok(component)
	}
	Status::INVALID_ARGS => {
	Err(ResolverError::url_parse_error(component_url, RemoteError(status)))
	}
	Status::NOT_FOUND => {
	Err(ResolverError::component_not_available(component_url, RemoteError(status)))
	}
	Status::UNAVAILABLE => {
	Err(ResolverError::manifest_invalid(component_url, RemoteError(status)))
	}
	_ => Err(ResolverError::unknown_resolver_error(RemoteError(status))),
	}
	})
	}
	}

	/// Errors produced by `Resolver`.
	#[derive(Debug, Error, Clone)]
	pub enum ResolverError {
	#[error("resolver is already registered for scheme \"{}\"", scheme)]
	DuplicateResolverError { scheme: String },
	#[error("component not available with url \"{}\": {}", url, err)]
	ComponentNotAvailable {
	url: String,
	#[source]
	err: ClonableError,
	},
	#[error("component manifest not available for url \"{}\": {}", url, err)]
	ManifestNotAvailable {
	url: String,
	#[source]
	err: ClonableError,
	},
	#[error("component manifest invalid for url \"{}\": {}", url, err)]
	ManifestInvalid {
	url: String,
	#[source]
	err: ClonableError,
	},
	#[error("Model not available.")]
	ModelAccessError,
	#[error("scheme not registered")]
	SchemeNotRegistered,
	#[error("failed to parse url \"{}\": {}", url, err)]
	UrlParseError {
	url: String,
	#[source]
	err: ClonableError,
	},
	#[error("url missing resource \"{}\"", url)]
	UrlMissingResourceError { url: String },
	#[error("failed to route resolver capability: {}", .0)]
	RoutingError(#[source] Box<ModelError>),
	#[error("the remote resolver returned invalid data")]
	RemoteInvalidData,
	#[error("an unknown error ocurred with the resolver: {}", .0)]
	UnknownResolverError(#[source] ClonableError),
	}

	impl ResolverError {
	pub fn component_not_available(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
	ResolverError::ComponentNotAvailable { url: url.into(), err: err.into().into() }
	}

	pub fn manifest_not_available(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
	ResolverError::ManifestNotAvailable { url: url.into(), err: err.into().into() }
	}

	pub fn manifest_invalid(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
	ResolverError::ManifestInvalid { url: url.into(), err: err.into().into() }
	}

	pub fn model_not_available() -> ResolverError {
	ResolverError::ModelAccessError
	}

	pub fn url_parse_error(url: impl Into<String>, err: impl Into<Error>) -> ResolverError {
	ResolverError::UrlParseError { url: url.into(), err: err.into().into() }
	}

	pub fn url_missing_resource_error(url: impl Into<String>) -> ResolverError {
	ResolverError::UrlMissingResourceError { url: url.into() }
	}

	pub fn routing_error(err: ModelError) -> ResolverError {
	ResolverError::RoutingError(Box::new(err))
	}

	pub fn unknown_resolver_error(err: impl Into<Error>) -> ResolverError {
	ResolverError::UnknownResolverError(err.into().into())
	}
	}

	#[derive(Error, Clone, Debug)]
	#[error("remote resolver returned status {}", .0)]
	struct RemoteError(Status);

	#[cfg(test)]
	mod tests {
	use {super::*, anyhow::format_err, matches::assert_matches};

	struct MockOkResolver {
	pub expected_url: String,
	pub resolved_url: String,
	}

	impl Resolver for MockOkResolver {
	fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
	assert_eq!(self.expected_url, component_url);
	Box::pin(future::ok(fsys::Component {
	resolved_url: Some(self.resolved_url.clone()),
	decl: Some(fsys::ComponentDecl {
	program: None,
	uses: None,
	exposes: None,
	offers: None,
	facets: None,
	capabilities: None,
	children: None,
	collections: None,
	environments: None,
	..fsys::ComponentDecl::EMPTY
	}),
	package: None,
	..fsys::Component::EMPTY
	}))
	}
	}

	struct MockErrorResolver {
	pub expected_url: String,
	pub error: Box<dyn Fn(&str) -> ResolverError + Send + Sync + 'static>,
	}

	impl Resolver for MockErrorResolver {
	fn resolve<'a>(&'a self, component_url: &'a str) -> ResolverFut<'a> {
	assert_eq!(self.expected_url, component_url);
	Box::pin(future::err((self.error)(component_url)))
	}
	}

	#[fuchsia_async::run_until_stalled(test)]
	async fn register_and_resolve() {
	let mut registry = ResolverRegistry::new();
	registry
	.register(
	"foo".to_string(),
	Box::new(MockOkResolver {
	expected_url: "foo://url".to_string(),
	resolved_url: "foo://resolved".to_string(),
	}),
	)
	.unwrap();
	registry
	.register(
	"bar".to_string(),
	Box::new(MockErrorResolver {
	expected_url: "bar://url".to_string(),
	error: Box::new(\|url\| {
	ResolverError::component_not_available(url, format_err!("not available"))
	}),
	}),
	)
	.unwrap();

	// Resolve known scheme that returns success.
	let component = registry.resolve("foo://url").await.unwrap();
	assert_eq!("foo://resolved", component.resolved_url.unwrap());

	// Resolve a different scheme that produces an error.
	let expected_res: Result<fsys::Component, ResolverError> =
	Err(ResolverError::component_not_available("bar://url", format_err!("not available")));
	assert_eq!(
	format!("{:?}", expected_res),
	format!("{:?}", registry.resolve("bar://url").await)
	);

	// Resolve an unknown scheme
	let expected_res: Result<fsys::Component, ResolverError> =
	Err(ResolverError::SchemeNotRegistered);
	assert_eq!(
	format!("{:?}", expected_res),
	format!("{:?}", registry.resolve("unknown://url").await),
	);

	// Resolve an URL lacking a scheme.
	let expected_res: Result<fsys::Component, ResolverError> =
	Err(ResolverError::url_parse_error("xxx", url::ParseError::RelativeUrlWithoutBase));
	assert_eq!(format!("{:?}", expected_res), format!("{:?}", registry.resolve("xxx").await),);
	}

	#[test]
	fn test_duplicate_registration() {
	let mut registry = ResolverRegistry::new();
	let resolver_a =
	MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
	let resolver_b =
	MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
	assert_matches!(registry.register("fuchsia-pkg".to_string(), Box::new(resolver_a)), Ok(()));
	assert_matches!(registry.register("fuchsia-pkg".to_string(), Box::new(resolver_b)), Err(ResolverRegistrationError::SchemeAlreadyRegistered(scheme)) if scheme == "fuchsia-pkg");
	}

	#[test]
	fn test_multiple_scheme_registration() {
	let mut registry = ResolverRegistry::new();
	let resolver_a =
	MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
	let resolver_b =
	MockOkResolver { expected_url: "".to_string(), resolved_url: "".to_string() };
	registry.register("fuchsia-pkg".to_string(), Box::new(resolver_a)).unwrap();
	registry.register("fuchsia-boot".to_string(), Box::new(resolver_b)).unwrap();
	}
	}