pdk_unit/tester/

unit_test.rs

// Copyright (c) 2026, Salesforce, Inc.,
// All rights reserved.
// For full license text, see the LICENSE.txt file
#[cfg(feature = "pdk")]
use crate::backends::{anypoint::AnypointBackend, ldap::LdapBackend, os::OSBackend};
use crate::host::implementation::{Call, FlowType};
use crate::host::{facade::HostFacade, implementation::ProxyWasmStub};
use crate::tester::io::UnitLogLevel;
use crate::tester::io::{RequestResponse, UnitHttpRequest, UnitHttpResponse};
use crate::tester::unit_test_request::InnerUnitTestRequest;
use crate::tester::websocket::{
    ConnectionInner, Direction, InnerUnitUpgrade, UnitTestUpgrade, UpgradeConnection,
};
use crate::{Backend, GrpcBackend, UnitGrpcRequest};
#[cfg(feature = "pdk")]
use classy::Entrypoint;
#[cfg(feature = "pdk")]
use non_exhaustive::non_exhaustive;
#[cfg(feature = "pdk")]
use pdk_core::host::context::root::RootContextAdapter;
#[cfg(feature = "pdk")]
use pdk_core::init::configure;
#[cfg(feature = "pdk")]
use pdk_core::policy_context::api::{
    ApiMetadata, FlexMetadata, Metadata, PlatformMetadata, PolicyMetadata,
};
#[cfg(feature = "pdk")]
use pdk_core::policy_context::metadata::{
    AnypointContext, Api, ApiContext, ApiSla as CoreApiSla, EnvironmentContext,
    IdentityManagementContext, Tier as CoreTier,
};
use proxy_wasm_stub::stub::set_host;
use proxy_wasm_stub::traits::{Context, RootContext};
use proxy_wasm_stub::types::{BufferType, MapType};
use std::backtrace::Backtrace;
use std::cell::RefCell;
use std::collections::HashMap;
use std::panic;
use std::rc::Rc;
use std::rc::Weak;
use std::task::Poll;
use std::thread;
use std::time::Duration;

#[cfg(feature = "pdk")]
pub(super) const IDENTITY_MANAGEMENT_SVC: &str = "__identity_management_svc";
const CHUNK_SIZE: usize = 30_000;

/// The main test orchestrator for running PDK policy unit tests.
///
/// This struct manages the Proxy-Wasm host stub, handles request lifecycles,
/// and coordinates interactions between the policy under test and mock backends.
///
/// Created via [`UnitTestBuilder`](crate::UnitTestBuilder).
pub struct UnitTest {
    host: Rc<RefCell<ProxyWasmStub>>,
    context: Option<Box<dyn RootContext>>,
    context_count: u32,
    requests: Vec<UnitTestRequest>,
    upgrades: Vec<UnitTestUpgrade>,
    connections: Vec<Weak<RefCell<ConnectionInner>>>,
    backends: Rc<RefCell<Backends>>,
    #[cfg(feature = "pdk")]
    anypoint: Rc<AnypointBackend>,
    #[cfg(feature = "pdk")]
    ldap: Rc<LdapBackend>,
    stop_mode: Option<StopIterationMode>,
    chunk_size: usize,
    log_level: UnitLogLevel,
    config: UnitTestConfig,
    factory: Box<dyn Fn() -> Box<dyn RootContext>>,
}

pub(crate) struct Backends {
    pub backend: Box<dyn Backend>,
    pub upstreams: HashMap<String, Rc<dyn Backend>>,
    pub grpc_upstreams: HashMap<String, Rc<dyn GrpcBackend>>,
}

/// Controls in which order how the test framework handles forwarding call responses and body processing
/// when using the stop_iteration mode.
///
/// This is only available when the `enable_stop_iteration` feature is enabled.
#[derive(PartialOrd, PartialEq, Copy, Clone, Debug)]
pub enum StopIterationMode {
    /// Process the call responses first and then the event body.
    RequestsThenBody,
    /// Process the event body first and then the call responses.
    BodyThenRequests,
}

pub(crate) struct UnitTestConfig {
    pub(crate) policy_config: String,
    #[cfg(feature = "pdk")]
    pub(crate) metadata: Metadata,
    #[cfg(feature = "pdk")]
    pub(crate) identity_management: Option<String>,
    #[cfg(feature = "pdk")]
    pub(crate) local_mode: bool,
}

impl Default for UnitTestConfig {
    fn default() -> Self {
        #[cfg(feature = "pdk")]
        {
            let policy_name = "test_policy_id".to_string();
            let policy_namespace = "test_policy_namespace".to_string();
            let api_name = "test_api_id".to_string();
            let filter_name = format!("{policy_name}.{policy_namespace}.{api_name}");

            Self {
                policy_config: "{}".to_string(),
                metadata: non_exhaustive!(Metadata {
                    flex_metadata: non_exhaustive!(FlexMetadata {
                        flex_name: "test_flex_name".to_string(),
                        flex_version: "1.0.0".to_string(),
                    }),
                    policy_metadata: non_exhaustive!(PolicyMetadata {
                        policy_name: policy_name,
                        policy_namespace: policy_namespace,
                        filter_name: filter_name,
                    }),
                    api_metadata: non_exhaustive!(ApiMetadata {
                        id: Some("1".to_string()),
                        name: Some(api_name),
                        version: Some("1.0.0".to_string()),
                        base_path: Some("/".to_string()),
                        slas: None,
                    }),
                    platform_metadata: non_exhaustive!(PlatformMetadata {
                        organization_id: "test-org-id".to_string(),
                        environment_id: "test-env-id".to_string(),
                        root_organization_id: "test-root-org-id".to_string(),
                    }),
                }),
                identity_management: None,
                local_mode: false,
            }
        }

        #[cfg(not(feature = "pdk"))]
        Self {
            policy_config: "{}".to_string(),
        }
    }
}

impl UnitTest {
    #[cfg(feature = "pdk")]
    pub(crate) fn new<C, T, E: Entrypoint<C, T> + Clone + 'static>(
        entrypoint: E,
        config: UnitTestConfig,
        mut backends: Backends,
    ) -> Self {
        let host = Rc::new(RefCell::new(ProxyWasmStub::default()));
        set_host(HostFacade::new(Rc::clone(&host)));

        let factory: Box<dyn Fn() -> Box<dyn RootContext>> = Box::new(move || {
            Box::new(RootContextAdapter::new(
                configure(0)
                    .entrypoint(entrypoint.clone())
                    .create_root_context(0),
            ))
        });

        // Register the upstreams before on_configure to be able to fire request from on_configure.
        let anypoint = Rc::new(AnypointBackend::default());
        let anypoint_ref = Rc::clone(&anypoint);
        backends
            .upstreams
            .entry("anypoint_service_name".to_string())
            .or_insert(anypoint_ref);

        let ldap = Rc::new(LdapBackend::default());
        let ldap_ref = Rc::clone(&ldap);
        backends
            .upstreams
            .entry("x-flex-services".to_string())
            .or_insert(ldap_ref);

        backends
            .upstreams
            .entry("x-flex-keyvalue-store".to_string())
            .or_insert(Rc::new(OSBackend::default()));

        let mut test = Self {
            host,
            context: None,
            context_count: 0,
            requests: Vec::new(),
            upgrades: Vec::new(),
            connections: Vec::new(),
            backends: Rc::new(RefCell::new(backends)),
            anypoint,
            ldap,
            #[cfg(feature = "enable_stop_iteration")]
            stop_mode: Some(StopIterationMode::BodyThenRequests),
            #[cfg(not(feature = "enable_stop_iteration"))]
            stop_mode: None,
            chunk_size: CHUNK_SIZE,
            log_level: UnitLogLevel::Trace,
            config,
            factory,
        };

        test.init();

        test
    }

    /// Creates a [`UnitTest`] from a raw proxy-wasm [`RootContext`] factory.
    ///
    /// Use this when the policy under test does not use the PDK framework and instead
    /// implements the proxy-wasm traits directly.
    #[cfg(feature = "proxy-wasm-rust-sdk")]
    pub(crate) fn new_with_context<F>(
        factory: F,
        config: UnitTestConfig,
        backends: Backends,
    ) -> Self
    where
        F: Fn() -> Box<dyn RootContext> + 'static,
    {
        let host = Rc::new(RefCell::new(ProxyWasmStub::default()));
        set_host(HostFacade::new(Rc::clone(&host)));

        let mut test = Self {
            host,
            context: None,
            context_count: 0,
            requests: Vec::new(),
            upgrades: Vec::new(),
            connections: Vec::new(),
            backends: Rc::new(RefCell::new(backends)),
            #[cfg(feature = "pdk")]
            anypoint: Rc::new(AnypointBackend::default()),
            #[cfg(feature = "pdk")]
            ldap: Rc::new(LdapBackend::default()),
            #[cfg(feature = "enable_stop_iteration")]
            stop_mode: Some(StopIterationMode::BodyThenRequests),
            #[cfg(not(feature = "enable_stop_iteration"))]
            stop_mode: None,
            chunk_size: CHUNK_SIZE,
            log_level: UnitLogLevel::Trace,
            config,
            factory: Box::new(factory),
        };

        test.init();

        test
    }

    fn init(&mut self) {
        let host = &self.host;

        host.borrow_mut().set_log_level(self.log_level);

        // Create factory context
        self.context_count = 1;
        host.borrow_mut().create_context(0);
        host.borrow_mut().create_buffer(
            0,
            BufferType::PluginConfiguration,
            self.config.policy_config.as_bytes().to_vec(),
        );
        host.borrow_mut().set_context(0);

        #[cfg(feature = "pdk")]
        setup_metadata(host, &self.config);

        // Create & initialize factory
        let factory = &self.factory;
        self.context = Some(factory());

        enrich_panic_hook();

        self.backends
            .borrow()
            .upstreams
            .keys()
            .for_each(|key| host.borrow_mut().add_upstream(key.to_string()));
        self.backends
            .borrow()
            .grpc_upstreams
            .keys()
            .for_each(|key| host.borrow_mut().add_upstream(key.to_string()));

        self.context
            .as_mut()
            .unwrap()
            .on_configure(self.config.policy_config.len());

        // Respond to any pending calls triggered during on_configure.
        self.respond_calls();
    }

    /// Simulate a system restart by cleaning all contexts and keeping the configured upstreams.
    pub fn restart(&mut self) {
        // Clear pending requests
        self.requests.clear();
        self.upgrades.clear();
        self.connections.clear();

        // Create a new host
        let mut host = ProxyWasmStub::default();
        host.clock = self.host.borrow().clock;
        let host = Rc::new(RefCell::new(host));
        set_host(HostFacade::new(Rc::clone(&host)));
        self.host = host;

        self.init();
    }

    /// Sets the minimum log level. Log messages below this level are suppressed.
    pub fn set_log_level(&mut self, level: UnitLogLevel) {
        self.log_level = level;
        self.host.borrow_mut().set_log_level(level);
    }

    /// Sets the stop iteration mode for handling paused requests.
    ///
    /// Only available when the `enable_stop_iteration` feature is enabled.
    #[cfg(feature = "enable_stop_iteration")]
    pub fn set_host_mode(&mut self, mode: StopIterationMode) {
        self.stop_mode = Some(mode);
    }

    #[cfg(feature = "experimental")]
    pub fn get_metrics(&mut self) -> HashMap<String, u64> {
        self.host
            .borrow()
            .get_metrics()
            .into_iter()
            .map(|(_id, (name, value))| (name, value))
            .collect()
    }

    /// Sets the chunk size in bytes for body processing.
    ///
    /// Bodies larger than this size will be processed in multiple chunks.
    pub fn set_chunk_size(&mut self, chunk_size: usize) {
        self.chunk_size = chunk_size;
    }

    /// Sends a request through the policy and returns a handle to track its progress.
    ///
    /// The returned [`UnitTestRequest`] can be polled to advance the request
    /// through the policy lifecycle and eventually retrieve the response.
    pub fn request_partial(&mut self, request: UnitHttpRequest) -> UnitTestRequest {
        // Create new request context
        let request = request.inner;
        let context_id = self.context_count;
        self.context_count += 1;

        self.host.borrow_mut().create_context(context_id);

        let request = add_request_properties(request, context_id);
        let props = request.properties();

        self.host.borrow_mut().set_properties(context_id, props);
        self.host.borrow_mut().set_context(context_id);

        let http_context = self
            .context
            .as_ref()
            .unwrap()
            .create_http_context(context_id)
            .unwrap();

        let mut inner = UnitTestRequest::new(InnerUnitTestRequest::new(
            context_id,
            request,
            http_context,
            Rc::clone(&self.backends),
            Rc::clone(&self.host),
            self.stop_mode,
            self.chunk_size,
        ));

        if !inner.poll().is_ready() {
            self.requests.push(inner.clone())
        }

        inner
    }

    fn forward_requests(&mut self) {
        self.requests.retain_mut(|req| !req.poll().is_ready());
        self.upgrades.retain_mut(|req| match req.poll() {
            Poll::Ready(Ok(conn)) => {
                self.connections.push(conn.weak_inner());
                false
            }
            Poll::Ready(Err(_)) => false,
            Poll::Pending => true,
        });
        self.connections.retain(|conn| {
            if let Some(conn) = conn.upgrade() {
                conn.borrow_mut().resume(Direction::Upstream);
                conn.borrow_mut().resume(Direction::Downstream);
                true
            } else {
                false
            }
        })
    }

    fn do_tick(&mut self) {
        self.host.borrow_mut().set_context(0);
        self.host.borrow_mut().set_flow_mode(FlowType::Async);
        self.context.as_mut().unwrap().on_tick();
        self.forward_requests();
        self.respond_calls();
    }

    /// Advances the simulated time by one tick interval.
    ///
    /// This triggers `on_tick` callbacks and processes any pending requests.
    pub fn tick(&mut self) {
        if !self.host.borrow_mut().tick().is_zero() {
            self.do_tick();
        }
    }

    /// Advances the simulated time by the specified duration.
    ///
    /// This will trigger multiple ticks if the duration spans multiple tick intervals.
    pub fn sleep(&mut self, duration: Duration) {
        let mut accumulated = Duration::new(0, 0);
        while accumulated < duration {
            let elapsed = self.host.borrow_mut().tick();
            if elapsed.is_zero() {
                self.host.borrow_mut().forward(duration - accumulated);
                return;
            }
            accumulated += elapsed;
            self.do_tick();
        }
    }

    /// Starts the WebSocket upgrade handshake and returns a handle to track its progress.
    ///
    /// The returned [`UnitTestUpgrade`] can be polled to advance the upgrade through
    /// `on_http_request_headers` and `on_http_response_headers`. Pending async call
    /// responses are resolved by [`tick`](Self::tick) / [`sleep`](Self::sleep) just like
    /// regular requests.
    pub fn upgrade_partial(&mut self, request: UnitHttpRequest) -> UnitTestUpgrade {
        let request = request.inner;
        let context_id = self.context_count;
        self.context_count += 1;

        self.host.borrow_mut().create_context(context_id);

        let request = add_request_properties(request, context_id);
        let props = request.properties();
        self.host.borrow_mut().set_properties(context_id, props);
        self.host.borrow_mut().set_context(context_id);

        let http_context = self
            .context
            .as_ref()
            .unwrap()
            .create_http_context(context_id)
            .unwrap();

        let upgrade = UnitTestUpgrade::new(InnerUnitUpgrade::new(
            context_id,
            request,
            http_context,
            Rc::clone(&self.backends),
            Rc::clone(&self.host),
            self.chunk_size,
        ));

        self.upgrades.push(upgrade.clone());

        upgrade
    }

    /// Drives an HTTP upgrade handshake through the policy and blocks until it completes.
    ///
    /// Returns `Ok(`[`UpgradeConnection`]`)` when the upgrade succeeds or
    /// `Err(`[`UnitHttpResponse`]`)` if the policy rejected the request. Ticks are run
    /// automatically while waiting, matching the behavior of [`request`](Self::request).
    pub fn upgrade(
        &mut self,
        request: UnitHttpRequest,
    ) -> Result<UpgradeConnection, UnitHttpResponse> {
        let mut handle = self.upgrade_partial(request);

        loop {
            match handle.poll() {
                Poll::Ready(res) => {
                    return res;
                }
                Poll::Pending => self.tick(),
            }
        }
    }

    /// Sends a request and blocks until the full response is received.
    ///
    /// This is a convenience method that combines `request_partial()` with polling
    /// until completion. Use this for simple synchronous test scenarios.
    pub fn request(&mut self, request: UnitHttpRequest) -> UnitHttpResponse {
        let mut response = self.request_partial(request);

        loop {
            if let Poll::Ready(value) = response.poll() {
                return value;
            } else {
                self.tick()
            }
        }
    }

    #[cfg(feature = "experimental_logs")]
    pub fn logs(&self) -> Vec<String> {
        self.host.borrow().logs.borrow().clone()
    }

    fn respond_calls(&mut self) {
        let mut pending_calls = self.host.borrow_mut().pending_calls(0);
        while !pending_calls.is_empty() {
            for (id, upstream, call) in pending_calls.into_iter() {
                respond_call(
                    self.context.as_deref_mut().unwrap(),
                    &self.host,
                    &self.backends,
                    0,
                    id,
                    upstream,
                    call,
                );
            }
            pending_calls = self.host.borrow_mut().pending_calls(0);
        }
    }
}

#[cfg(feature = "pdk")]
impl UnitTest {
    /// Adds contract data for client ID enforcement testing.
    ///
    /// This simulates registered API contracts in the Anypoint Platform.
    pub fn add_contract_data<I, N, S, Sla>(
        &mut self,
        id: I,
        name: N,
        secret: Option<S>,
        sla_id: Option<Sla>,
    ) where
        I: Into<String>,
        N: Into<String>,
        S: Into<String>,
        Sla: Into<String>,
    {
        self.anypoint.add_contract(
            id.into(),
            name.into(),
            secret.map(|s| s.into()),
            sla_id.map(|sla| sla.into()),
        );
    }

    /// Removes contract data for client ID enforcement testing.
    pub fn remove_contract_data<I>(&mut self, id: I)
    where
        I: Into<String>,
    {
        self.anypoint.remove_contract(id.into());
    }

    #[cfg(feature = "pdk")]
    /// Registers a valid LDAP credential pair for use during testing.
    ///
    /// If `config` is [`Some`], the pair is matched only when the policy uses
    /// LDAP connection parameters equal to that config. If `config` is [`None`],
    /// the pair acts as a wildcard and matches regardless of the LDAP config.
    ///
    /// # Arguments
    ///
    /// * `config` - Optional LDAP server configuration to scope this credential to.
    /// * `user` - The username that should be considered valid.
    /// * `pass` - The password that should be considered valid for `user`.
    pub fn add_ldap_data<U, P>(&mut self, config: Option<crate::UnitLdapConfig>, user: U, pass: P)
    where
        U: Into<String>,
        P: Into<String>,
    {
        self.ldap.add_data(config, user, pass);
    }
}

/// A handle to an in-flight request being processed by the policy.
///
/// Use `poll()` to advance the request through the policy lifecycle.
#[derive(Clone)]
pub struct UnitTestRequest {
    inner: Rc<RefCell<InnerUnitTestRequest>>,
}

impl UnitTestRequest {
    pub(crate) fn new(inner: InnerUnitTestRequest) -> Self {
        Self {
            inner: Rc::new(RefCell::new(inner)),
        }
    }

    /// Advances the request processing and returns the current state.
    ///
    /// Returns `Poll::Ready(response)` when the request is complete,
    /// or `Poll::Pending` if more processing is needed.
    pub fn poll(&mut self) -> Poll<UnitHttpResponse> {
        self.inner.borrow_mut().poll()
    }
}

#[cfg(feature = "pdk")]
fn setup_metadata(host: &Rc<RefCell<ProxyWasmStub>>, config: &UnitTestConfig) {
    let api_name = config
        .metadata
        .api_metadata
        .name
        .clone()
        .unwrap_or_default();
    let policy_name = &config.metadata.policy_metadata.policy_name;
    let policy_namespace = &config.metadata.policy_metadata.policy_namespace;

    let filter_name = format!("{policy_name}.{policy_namespace}.{api_name}");

    host.borrow_mut().create_property(
        0,
        vec!["node", "id"],
        Some(config.metadata.flex_metadata.flex_name.clone()),
    );
    host.borrow_mut()
        .create_property(0, vec!["plugin_name"], Some(filter_name));

    let context = match config.local_mode {
        true => local_context(config),
        false => connected_context(config),
    };

    let context = serde_json::to_string(&context).unwrap();

    host.borrow_mut().create_property(
        0,
        vec![
            "listener_metadata",
            "filter_metadata",
            config
                .metadata
                .api_metadata
                .name
                .as_deref()
                .unwrap_or_default(),
            "context",
        ],
        Some(context),
    )
}

#[cfg(feature = "pdk")]
fn local_context(config: &UnitTestConfig) -> ApiContext {
    let environment = EnvironmentContext::new(
        config.metadata.platform_metadata.organization_id.clone(),
        config.metadata.platform_metadata.environment_id.clone(),
        config
            .metadata
            .platform_metadata
            .root_organization_id
            .clone(),
        "test_cluster_id".to_string(),
        None,
        None,
    );

    ApiContext::new(None, None, None, None, Some(environment), None)
}

#[cfg(feature = "pdk")]
fn connected_context(config: &UnitTestConfig) -> ApiContext {
    let tiers = config
        .metadata
        .api_metadata
        .slas
        .as_ref()
        .map(|slas| {
            slas.iter()
                .map(|sla| {
                    CoreApiSla::new(
                        sla.id.clone(),
                        sla.name.clone(),
                        sla.tiers
                            .iter()
                            .map(|tier| CoreTier::new(tier.requests, tier.period_in_millis))
                            .collect(),
                    )
                })
                .collect::<Vec<_>>()
        })
        .unwrap_or_default();

    #[cfg(feature = "experimental")]
    let exchange_context = config.metadata.api_metadata.asset.as_ref().map(|ctx| {
        pdk_core::policy_context::metadata::ExchangeContext::new(
            ctx.service.cluster_name().to_string(),
            ctx.service.uri().to_string(),
        )
    });

    #[cfg(not(feature = "experimental"))]
    let exchange_context = None;

    let mut api = Api::new(
        config.metadata.api_metadata.id.clone().unwrap_or_default(),
        config
            .metadata
            .api_metadata
            .name
            .clone()
            .unwrap_or_default(),
        "v1".to_string(),
        config
            .metadata
            .api_metadata
            .version
            .clone()
            .unwrap_or_default(),
        exchange_context,
    );

    if let Some(path) = config.metadata.api_metadata.base_path.as_ref() {
        api.set_base_path(path.clone())
    }

    let anypoint = AnypointContext::new(
        "test_client".to_string(),
        "test_secret".to_string(),
        "anypoint_service_name".to_string(),
        "https://anypoint.mulesoft.com".to_string(),
    );

    let environment = EnvironmentContext::new(
        config.metadata.platform_metadata.organization_id.clone(),
        config.metadata.platform_metadata.environment_id.clone(),
        config
            .metadata
            .platform_metadata
            .root_organization_id
            .clone(),
        "test_cluster_id".to_string(),
        Some(anypoint),
        None,
    );

    let identity = config.identity_management.as_ref().map(|url| {
        IdentityManagementContext::new(
            "client_id".to_string(),
            "client_secret".to_string(),
            url.clone(),
            IDENTITY_MANAGEMENT_SVC.to_string(),
        )
    });

    ApiContext::new(
        None,
        Some(api),
        Some(tiers),
        identity,
        Some(environment),
        None,
    )
}

fn enrich_panic_hook() {
    let hook = panic::take_hook();

    let thread_id = thread::current().id();
    panic::set_hook(Box::new(move |panic_info| {
        hook(panic_info);
        if thread::current().id() == thread_id {
            println!("{}", Backtrace::capture());
        }
    }));
}

pub(crate) fn add_request_properties(request: RequestResponse, context_id: u32) -> RequestResponse {
    let request = request
        .with_property_if_missing(&["request", "id"], context_id.to_string())
        .with_property_if_missing(&["source", "address"], "127.0.0.1")
        .with_property_if_missing(&["destination", "address"], "127.0.0.2")
        .with_property_if_missing(&["request", "scheme"], "http")
        .with_property_if_missing(&["request", "protocol"], "1.1");

    #[cfg(feature = "pdk")]
    let request =
        request.with_property_if_missing(&["anypoint/mulesoft/tracing_id"], context_id.to_string());

    request
}

pub(crate) fn respond_http<C: Context + ?Sized>(
    context: &mut C,
    host: &Rc<RefCell<ProxyWasmStub>>,
    backends: &Rc<RefCell<Backends>>,
    context_id: u32,
    id: u32,
    upstream: String,
    req: RequestResponse,
) {
    let response = backends
        .borrow()
        .upstreams
        .get(&upstream)
        .unwrap()
        .call(req.into())
        .inner;
    let response_headers = response.headers.len();
    let response_body = response.body.len();

    host.borrow_mut().create_map(
        context_id,
        MapType::HttpCallResponseHeaders,
        response
            .headers
            .into_iter()
            .map(|(k, v)| (k, v.into_bytes()))
            .collect(),
    );
    host.borrow_mut()
        .create_buffer(context_id, BufferType::HttpCallResponseBody, response.body);
    context.on_http_call_response(id, response_headers, response_body, 0);
}

pub(crate) fn respond_grpc<C: Context + ?Sized>(
    context: &mut C,
    host: &Rc<RefCell<ProxyWasmStub>>,
    backends: &Rc<RefCell<Backends>>,
    context_id: u32,
    id: u32,
    upstream: String,
    req: UnitGrpcRequest,
) {
    let response = backends
        .borrow()
        .grpc_upstreams
        .get(&upstream)
        .unwrap()
        .call(req);

    host.borrow_mut()
        .set_grpc_status((response.status_code, response.status));

    let body_len = response.message.len();
    host.borrow_mut()
        .create_buffer(context_id, BufferType::GrpcReceiveBuffer, response.message);

    context.on_grpc_call_response(id, response.status_code, body_len)
}

pub(crate) fn respond_call<C: Context + ?Sized>(
    context: &mut C,
    host: &Rc<RefCell<ProxyWasmStub>>,
    backends: &Rc<RefCell<Backends>>,
    context_id: u32,
    id: u32,
    upstream: String,
    call: Call,
) {
    match call {
        Call::Http(req) => respond_http(context, host, backends, context_id, id, upstream, req),
        Call::Grpc(req) => respond_grpc(context, host, backends, context_id, id, upstream, req),
    }
}