iota_move_natives_latest/

test_scenario.rs

// Copyright (c) Mysten Labs, Inc.
// Modifications Copyright (c) 2024 IOTA Stiftung
// SPDX-License-Identifier: Apache-2.0

use std::{
    borrow::Borrow,
    cell::RefCell,
    collections::{BTreeMap, BTreeSet, VecDeque},
    thread::LocalKey,
};

use better_any::{Tid, TidAble};
use indexmap::{IndexMap, IndexSet};
use iota_types::{
    TypeTag,
    base_types::{IotaAddress, ObjectID, SequenceNumber},
    config,
    digests::{ObjectDigest, TransactionDigest},
    dynamic_field::DynamicFieldInfo,
    execution::DynamicallyLoadedObjectMetadata,
    id::UID,
    in_memory_storage::InMemoryStorage,
    object::{MoveObject, Object, Owner},
    storage::ChildObjectResolver,
};
use move_binary_format::errors::{PartialVMError, PartialVMResult};
use move_core_types::{
    account_address::AccountAddress,
    annotated_value::{MoveFieldLayout, MoveStructLayout, MoveTypeLayout, MoveValue},
    annotated_visitor as AV,
    language_storage::StructTag,
    vm_status::StatusCode,
};
use move_vm_runtime::native_functions::NativeContext;
use move_vm_types::{
    loaded_data::runtime_types::Type,
    natives::function::NativeResult,
    pop_arg,
    values::{self, StructRef, Value},
};
use smallvec::smallvec;

use crate::{
    get_nth_struct_field, get_tag_and_layouts, legacy_test_cost,
    object_runtime::{ObjectRuntime, RuntimeResults},
};

const E_COULD_NOT_GENERATE_EFFECTS: u64 = 0;
const E_INVALID_SHARED_OR_IMMUTABLE_USAGE: u64 = 1;
const E_OBJECT_NOT_FOUND_CODE: u64 = 4;
const E_UNABLE_TO_ALLOCATE_RECEIVING_TICKET: u64 = 5;
const E_RECEIVING_TICKET_ALREADY_ALLOCATED: u64 = 6;
const E_UNABLE_TO_DEALLOCATE_RECEIVING_TICKET: u64 = 7;

type Set<K> = IndexSet<K>;

/// An in-memory test store is a thin wrapper around the in-memory storage in a
/// mutex. The mutex allows this to be used by both the object runtime (for
/// reading) and the test scenario (for writing) while hiding mutability.
#[derive(Tid)]
pub struct InMemoryTestStore(pub &'static LocalKey<RefCell<InMemoryStorage>>);

impl ChildObjectResolver for InMemoryTestStore {
    fn read_child_object(
        &self,
        parent: &ObjectID,
        child: &ObjectID,
        child_version_upper_bound: SequenceNumber,
    ) -> iota_types::error::IotaResult<Option<Object>> {
        let l: &'static LocalKey<RefCell<InMemoryStorage>> = self.0;
        l.with_borrow(|store| store.read_child_object(parent, child, child_version_upper_bound))
    }

    fn get_object_received_at_version(
        &self,
        owner: &ObjectID,
        receiving_object_id: &ObjectID,
        receive_object_at_version: SequenceNumber,
        epoch_id: iota_types::committee::EpochId,
    ) -> iota_types::error::IotaResult<Option<Object>> {
        self.0.with_borrow(|store| {
            store.get_object_received_at_version(
                owner,
                receiving_object_id,
                receive_object_at_version,
                epoch_id,
            )
        })
    }
}

// This function updates the inventories based on the transfers and deletes that
// occurred in the transaction
// native fun end_transaction(): TransactionResult;
pub fn end_transaction(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    assert!(ty_args.is_empty());
    assert!(args.is_empty());
    let object_runtime_ref: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let taken_shared_or_imm: BTreeMap<_, _> = object_runtime_ref
        .test_inventories
        .taken
        .iter()
        .filter(|(_id, owner)| matches!(owner, Owner::Shared { .. } | Owner::Immutable))
        .map(|(id, owner)| (*id, *owner))
        .collect();
    // set to true if a shared or imm object was:
    // - transferred in a way that changes it from its original shared/imm state
    // - wraps the object
    // if true, we will "abort"
    let mut incorrect_shared_or_imm_handling = false;

    // Handle the allocated tickets:
    // * Remove all allocated_tickets in the test inventories.
    // * For each allocated ticket, if the ticket's object ID is loaded, move it to
    //   `received`.
    // * Otherwise re-insert the allocated ticket into the objects inventory, and
    //   mark it to be removed from the backing storage (deferred due to needing to
    //   have access to `context` which has outstanding references at this point).
    let allocated_tickets =
        std::mem::take(&mut object_runtime_ref.test_inventories.allocated_tickets);
    let mut received = BTreeMap::new();
    let mut unreceived = BTreeSet::new();
    let loaded_runtime_objects = object_runtime_ref.loaded_runtime_objects();
    for (id, (metadata, value)) in allocated_tickets {
        if loaded_runtime_objects.contains_key(&id) {
            received.insert(id, metadata);
        } else {
            unreceived.insert(id);
            // This must be untouched since the allocated ticket is still live, so ok to
            // re-insert.
            object_runtime_ref
                .test_inventories
                .objects
                .insert(id, value);
        }
    }

    let object_runtime_state = object_runtime_ref.take_state();
    // Determine writes and deletes
    // We pass the received objects since they should be viewed as "loaded" for the
    // purposes of of calculating the effects of the transaction.
    let results = object_runtime_state.finish(received, BTreeMap::new());
    let RuntimeResults {
        writes,
        user_events,
        loaded_child_objects: _,
        created_object_ids,
        deleted_object_ids,
    } = match results {
        Ok(res) => res,
        Err(_) => {
            return Ok(NativeResult::err(
                legacy_test_cost(),
                E_COULD_NOT_GENERATE_EFFECTS,
            ));
        }
    };
    let object_runtime_ref: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let all_active_child_objects_with_values = object_runtime_ref
        .all_active_child_objects()
        .filter(|child| child.copied_value.is_some())
        .map(|child| *child.id)
        .collect::<BTreeSet<_>>();
    let inventories = &mut object_runtime_ref.test_inventories;
    let mut new_object_values = IndexMap::new();
    let mut transferred = vec![];
    // cleanup inventories
    // we will remove all changed objects
    // - deleted objects need to be removed to mark deletions
    // - written objects are removed and later replaced to mark new values and new
    //   owners
    // - child objects will not be reflected in transfers, but need to be no longer
    //   retrievable
    for id in deleted_object_ids
        .iter()
        .chain(writes.keys())
        .chain(&all_active_child_objects_with_values)
    {
        for addr_inventory in inventories.address_inventories.values_mut() {
            for s in addr_inventory.values_mut() {
                s.shift_remove(id);
            }
        }
        for s in &mut inventories.shared_inventory.values_mut() {
            s.shift_remove(id);
        }
        for s in &mut inventories.immutable_inventory.values_mut() {
            s.shift_remove(id);
        }
        inventories.taken.remove(id);
    }

    // handle transfers, inserting transferred/written objects into their respective
    // inventory
    let mut created = vec![];
    let mut written = vec![];
    for (id, (owner, ty, value)) in writes {
        // write configs to cache
        new_object_values.insert(id, (ty.clone(), value.copy_value().unwrap()));
        transferred.push((id, owner));
        incorrect_shared_or_imm_handling = incorrect_shared_or_imm_handling
            || taken_shared_or_imm
                .get(&id)
                .map(|shared_or_imm_owner| shared_or_imm_owner != &owner)
                .unwrap_or(/* not incorrect */ false);
        if created_object_ids.contains(&id) {
            created.push(id);
        } else {
            written.push(id);
        }
        match owner {
            Owner::AddressOwner(a) => {
                inventories
                    .address_inventories
                    .entry(a)
                    .or_default()
                    .entry(ty)
                    .or_default()
                    .insert(id);
            }
            Owner::ObjectOwner(_) => (),
            Owner::Shared { .. } => {
                inventories
                    .shared_inventory
                    .entry(ty)
                    .or_default()
                    .insert(id);
            }
            Owner::Immutable => {
                inventories
                    .immutable_inventory
                    .entry(ty)
                    .or_default()
                    .insert(id);
            }
        }
    }

    // For any unused allocated tickets, remove them from the store.
    let store: &&InMemoryTestStore = context.extensions().get();
    for id in unreceived {
        if store
            .0
            .with_borrow_mut(|store| store.remove_object(id).is_none())
        {
            return Ok(NativeResult::err(
                context.gas_used(),
                E_UNABLE_TO_DEALLOCATE_RECEIVING_TICKET,
            ));
        }
    }

    // deletions already handled above, but we drop the delete kind for the effects
    let mut deleted = vec![];
    for id in deleted_object_ids {
        // Mark as "incorrect" if a imm object was deleted. Allow shared objects to be
        // deleted though.
        incorrect_shared_or_imm_handling = incorrect_shared_or_imm_handling
            || taken_shared_or_imm
                .get(&id)
                .is_some_and(|owner| matches!(owner, Owner::Immutable));
        deleted.push(id);
    }
    // find all wrapped objects
    let mut all_wrapped = BTreeSet::new();
    let object_runtime_ref: &ObjectRuntime = context.extensions().get();
    find_all_wrapped_objects(
        context,
        &mut all_wrapped,
        new_object_values
            .iter()
            .map(|(id, (ty, value))| (id, ty, value)),
    );
    find_all_wrapped_objects(
        context,
        &mut all_wrapped,
        object_runtime_ref
            .all_active_child_objects()
            .filter_map(|child| Some((child.id, child.ty, child.copied_value?))),
    );
    // mark as "incorrect" if a shared/imm object was wrapped or is a child object
    incorrect_shared_or_imm_handling = incorrect_shared_or_imm_handling
        || taken_shared_or_imm.keys().any(|id| {
            all_wrapped.contains(id) || all_active_child_objects_with_values.contains(id)
        });
    // if incorrect handling, return with an 'abort'
    if incorrect_shared_or_imm_handling {
        return Ok(NativeResult::err(
            legacy_test_cost(),
            E_INVALID_SHARED_OR_IMMUTABLE_USAGE,
        ));
    }

    // mark all wrapped as deleted
    for wrapped in all_wrapped {
        deleted.push(wrapped)
    }

    // new input objects are remaining taken objects not written/deleted
    let object_runtime_ref: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let mut config_settings = vec![];
    for child in object_runtime_ref.all_active_child_objects() {
        let s: StructTag = child.move_type.clone().into();
        let is_setting = DynamicFieldInfo::is_dynamic_field(&s)
            && matches!(&s.type_params[1], TypeTag::Struct(s) if config::is_setting(s));
        if is_setting {
            config_settings.push((
                *child.owner,
                *child.id,
                child.move_type.clone(),
                child.copied_value,
            ));
        }
    }
    for (config, setting, ty, value) in config_settings {
        object_runtime_ref.config_setting_cache_update(config, setting, ty, value)
    }
    object_runtime_ref.state.input_objects = object_runtime_ref
        .test_inventories
        .taken
        .iter()
        .map(|(id, owner)| (*id, *owner))
        .collect::<BTreeMap<_, _>>();
    // update inventories
    // check for bad updates to immutable values
    for (id, (ty, value)) in new_object_values {
        debug_assert!(!all_active_child_objects_with_values.contains(&id));
        if let Some(prev_value) = object_runtime_ref
            .test_inventories
            .taken_immutable_values
            .get(&ty)
            .and_then(|values| values.get(&id))
        {
            if !value.equals(prev_value)? {
                return Ok(NativeResult::err(
                    legacy_test_cost(),
                    E_INVALID_SHARED_OR_IMMUTABLE_USAGE,
                ));
            }
        }
        object_runtime_ref
            .test_inventories
            .objects
            .insert(id, value);
    }
    // remove deleted
    for id in &deleted {
        object_runtime_ref.test_inventories.objects.remove(id);
    }
    // remove active child objects
    for id in all_active_child_objects_with_values {
        object_runtime_ref.test_inventories.objects.remove(&id);
    }

    let effects = transaction_effects(
        created,
        written,
        deleted,
        transferred,
        user_events.len() as u64,
    );
    Ok(NativeResult::ok(legacy_test_cost(), smallvec![effects]))
}

// native fun take_from_address_by_id<T: key>(account: address, id: ID): T;
pub fn take_from_address_by_id(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    let id = pop_id(&mut args)?;
    let account: IotaAddress = pop_arg!(args, AccountAddress).into();
    pop_arg!(args, StructRef);
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let res = take_from_inventory(
        |x| {
            inventories
                .address_inventories
                .get(&account)
                .and_then(|inv| inv.get(&specified_ty))
                .map(|s| s.contains(x))
                .unwrap_or(false)
        },
        &inventories.objects,
        &mut inventories.taken,
        &mut object_runtime.state.input_objects,
        id,
        Owner::AddressOwner(account),
    );
    Ok(match res {
        Ok(value) => NativeResult::ok(legacy_test_cost(), smallvec![value]),
        Err(native_err) => native_err,
    })
}

// native fun ids_for_address<T: key>(account: address): vector<ID>;
pub fn ids_for_address(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    let account: IotaAddress = pop_arg!(args, AccountAddress).into();
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let ids = inventories
        .address_inventories
        .get(&account)
        .and_then(|inv| inv.get(&specified_ty))
        .map(|s| s.iter().map(|id| pack_id(*id)).collect::<Vec<Value>>())
        .unwrap_or_default();
    let ids_vector = Value::vector_for_testing_only(ids);
    Ok(NativeResult::ok(legacy_test_cost(), smallvec![ids_vector]))
}

// native fun most_recent_id_for_address<T: key>(account: address): Option<ID>;
pub fn most_recent_id_for_address(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    let account: IotaAddress = pop_arg!(args, AccountAddress).into();
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let most_recent_id = match inventories.address_inventories.get(&account) {
        None => pack_option(None),
        Some(inv) => most_recent_at_ty(&inventories.taken, inv, specified_ty),
    };
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![most_recent_id],
    ))
}

// native fun was_taken_from_address(account: address, id: ID): bool;
pub fn was_taken_from_address(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    assert!(ty_args.is_empty());
    let id = pop_id(&mut args)?;
    let account: IotaAddress = pop_arg!(args, AccountAddress).into();
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let was_taken = inventories
        .taken
        .get(&id)
        .map(|owner| owner == &Owner::AddressOwner(account))
        .unwrap_or(false);
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![Value::bool(was_taken)],
    ))
}

// native fun take_immutable_by_id<T: key>(id: ID): T;
pub fn take_immutable_by_id(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    let id = pop_id(&mut args)?;
    pop_arg!(args, StructRef);
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let res = take_from_inventory(
        |x| {
            inventories
                .immutable_inventory
                .get(&specified_ty)
                .map(|s| s.contains(x))
                .unwrap_or(false)
        },
        &inventories.objects,
        &mut inventories.taken,
        &mut object_runtime.state.input_objects,
        id,
        Owner::Immutable,
    );
    Ok(match res {
        Ok(value) => {
            inventories
                .taken_immutable_values
                .entry(specified_ty)
                .or_default()
                .insert(id, value.copy_value().unwrap());
            NativeResult::ok(legacy_test_cost(), smallvec![value])
        }
        Err(native_err) => native_err,
    })
}

// native fun most_recent_immutable_id<T: key>(): Option<ID>;
pub fn most_recent_immutable_id(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let most_recent_id = most_recent_at_ty(
        &inventories.taken,
        &inventories.immutable_inventory,
        specified_ty,
    );
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![most_recent_id],
    ))
}

// native fun was_taken_immutable(id: ID): bool;
pub fn was_taken_immutable(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    assert!(ty_args.is_empty());
    let id = pop_id(&mut args)?;
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let was_taken = inventories
        .taken
        .get(&id)
        .map(|owner| owner == &Owner::Immutable)
        .unwrap_or(false);
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![Value::bool(was_taken)],
    ))
}

// native fun take_shared_by_id<T: key>(id: ID): T;
pub fn take_shared_by_id(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    let id = pop_id(&mut args)?;
    pop_arg!(args, StructRef);
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let res = take_from_inventory(
        |x| {
            inventories
                .shared_inventory
                .get(&specified_ty)
                .map(|s| s.contains(x))
                .unwrap_or(false)
        },
        &inventories.objects,
        &mut inventories.taken,
        &mut object_runtime.state.input_objects,
        id,
        Owner::Shared { initial_shared_version: /* dummy */ SequenceNumber::new() },
    );
    Ok(match res {
        Ok(value) => NativeResult::ok(legacy_test_cost(), smallvec![value]),
        Err(native_err) => native_err,
    })
}

// native fun most_recent_id_shared<T: key>(): Option<ID>;
pub fn most_recent_id_shared(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let specified_ty = get_specified_ty(ty_args);
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let most_recent_id = most_recent_at_ty(
        &inventories.taken,
        &inventories.shared_inventory,
        specified_ty,
    );
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![most_recent_id],
    ))
}

// native fun was_taken_shared(id: ID): bool;
pub fn was_taken_shared(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    assert!(ty_args.is_empty());
    let id = pop_id(&mut args)?;
    assert!(args.is_empty());
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    let was_taken = inventories
        .taken
        .get(&id)
        .map(|owner| matches!(owner, Owner::Shared { .. }))
        .unwrap_or(false);
    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![Value::bool(was_taken)],
    ))
}

pub fn allocate_receiving_ticket_for_object(
    context: &mut NativeContext,
    ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let ty = get_specified_ty(ty_args);
    let id = pop_id(&mut args)?;

    let Some((tag, layout, _)) = get_tag_and_layouts(context, &ty)? else {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_UNABLE_TO_ALLOCATE_RECEIVING_TICKET,
        ));
    };
    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let object_version = SequenceNumber::new();
    let inventories = &mut object_runtime.test_inventories;
    if inventories.allocated_tickets.contains_key(&id) {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_RECEIVING_TICKET_ALREADY_ALLOCATED,
        ));
    }

    let obj_value = inventories.objects.remove(&id).unwrap();
    let Some(bytes) = obj_value.simple_serialize(&layout) else {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_UNABLE_TO_ALLOCATE_RECEIVING_TICKET,
        ));
    };
    let move_object = {
        MoveObject::new_from_execution_with_limit(tag.into(), object_version, bytes, 250 * 1024)
    }
    .unwrap();

    let Some((owner, _)) = inventories
        .address_inventories
        .iter()
        .find(|(_addr, objs)| objs.iter().any(|(_, ids)| ids.contains(&id)))
    else {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_OBJECT_NOT_FOUND_CODE,
        ));
    };

    inventories.allocated_tickets.insert(
        id,
        (
            DynamicallyLoadedObjectMetadata {
                version: SequenceNumber::new(),
                digest: ObjectDigest::MIN,
                owner: Owner::AddressOwner(*owner),
                storage_rebate: 0,
                previous_transaction: TransactionDigest::default(),
            },
            obj_value,
        ),
    );

    let object = Object::new_move(
        move_object,
        Owner::AddressOwner(*owner),
        TransactionDigest::default(),
    );

    // NB: Must be a `&&` reference since the extension stores a static ref to the
    // object storage.
    let store: &&InMemoryTestStore = context.extensions().get();
    store.0.with_borrow_mut(|store| store.insert_object(object));

    Ok(NativeResult::ok(
        legacy_test_cost(),
        smallvec![Value::u64(object_version.value())],
    ))
}

pub fn deallocate_receiving_ticket_for_object(
    context: &mut NativeContext,
    _ty_args: Vec<Type>,
    mut args: VecDeque<Value>,
) -> PartialVMResult<NativeResult> {
    let id = pop_id(&mut args)?;

    let object_runtime: &mut ObjectRuntime = context.extensions_mut().get_mut();
    let inventories = &mut object_runtime.test_inventories;
    // Deallocate the ticket -- we should never hit this scenario
    let Some((_, value)) = inventories.allocated_tickets.remove(&id) else {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_UNABLE_TO_DEALLOCATE_RECEIVING_TICKET,
        ));
    };

    // Insert the object value that we saved from earlier and put it back into the
    // object set. This is fine since it can't have been touched.
    inventories.objects.insert(id, value);

    // Remove the object from storage. We should never hit this scenario either.
    let store: &&InMemoryTestStore = context.extensions().get();
    if store
        .0
        .with_borrow_mut(|store| store.remove_object(id).is_none())
    {
        return Ok(NativeResult::err(
            context.gas_used(),
            E_UNABLE_TO_DEALLOCATE_RECEIVING_TICKET,
        ));
    };

    Ok(NativeResult::ok(legacy_test_cost(), smallvec![]))
}

// impls

fn take_from_inventory(
    is_in_inventory: impl FnOnce(&ObjectID) -> bool,
    objects: &BTreeMap<ObjectID, Value>,
    taken: &mut BTreeMap<ObjectID, Owner>,
    input_objects: &mut BTreeMap<ObjectID, Owner>,
    id: ObjectID,
    owner: Owner,
) -> Result<Value, NativeResult> {
    let obj_opt = objects.get(&id);
    let is_taken = taken.contains_key(&id);
    if is_taken || !is_in_inventory(&id) || obj_opt.is_none() {
        return Err(NativeResult::err(
            legacy_test_cost(),
            E_OBJECT_NOT_FOUND_CODE,
        ));
    }
    taken.insert(id, owner);
    input_objects.insert(id, owner);
    let obj = obj_opt.unwrap();
    Ok(obj.copy_value().unwrap())
}

fn most_recent_at_ty(
    taken: &BTreeMap<ObjectID, Owner>,
    inv: &BTreeMap<Type, Set<ObjectID>>,
    ty: Type,
) -> Value {
    pack_option(most_recent_at_ty_opt(taken, inv, ty))
}

fn most_recent_at_ty_opt(
    taken: &BTreeMap<ObjectID, Owner>,
    inv: &BTreeMap<Type, Set<ObjectID>>,
    ty: Type,
) -> Option<Value> {
    let s = inv.get(&ty)?;
    let most_recent_id = s.iter().filter(|id| !taken.contains_key(id)).next_back()?;
    Some(pack_id(*most_recent_id))
}

fn get_specified_ty(mut ty_args: Vec<Type>) -> Type {
    assert!(ty_args.len() == 1);
    ty_args.pop().unwrap()
}

// helpers
fn pop_id(args: &mut VecDeque<Value>) -> PartialVMResult<ObjectID> {
    let v = match args.pop_back() {
        None => {
            return Err(PartialVMError::new(
                StatusCode::UNKNOWN_INVARIANT_VIOLATION_ERROR,
            ));
        }
        Some(v) => v,
    };
    Ok(get_nth_struct_field(v, 0)?
        .value_as::<AccountAddress>()?
        .into())
}

fn pack_id(a: impl Into<AccountAddress>) -> Value {
    Value::struct_(values::Struct::pack(vec![Value::address(a.into())]))
}

fn pack_ids(items: impl IntoIterator<Item = impl Into<AccountAddress>>) -> Value {
    Value::vector_for_testing_only(items.into_iter().map(pack_id))
}

fn pack_vec_map(items: impl IntoIterator<Item = (Value, Value)>) -> Value {
    Value::struct_(values::Struct::pack(vec![Value::vector_for_testing_only(
        items
            .into_iter()
            .map(|(k, v)| Value::struct_(values::Struct::pack(vec![k, v]))),
    )]))
}

fn transaction_effects(
    created: impl IntoIterator<Item = impl Into<AccountAddress>>,
    written: impl IntoIterator<Item = impl Into<AccountAddress>>,
    deleted: impl IntoIterator<Item = impl Into<AccountAddress>>,
    transferred: impl IntoIterator<Item = (ObjectID, Owner)>,
    num_events: u64,
) -> Value {
    let mut transferred_to_account = vec![];
    let mut transferred_to_object = vec![];
    let mut shared = vec![];
    let mut frozen = vec![];
    for (id, owner) in transferred {
        match owner {
            Owner::AddressOwner(a) => {
                transferred_to_account.push((pack_id(id), Value::address(a.into())))
            }
            Owner::ObjectOwner(o) => transferred_to_object.push((pack_id(id), pack_id(o))),
            Owner::Shared { .. } => shared.push(id),
            Owner::Immutable => frozen.push(id),
        }
    }

    let created_field = pack_ids(created);
    let written_field = pack_ids(written);
    let deleted_field = pack_ids(deleted);
    let transferred_to_account_field = pack_vec_map(transferred_to_account);
    let transferred_to_object_field = pack_vec_map(transferred_to_object);
    let shared_field = pack_ids(shared);
    let frozen_field = pack_ids(frozen);
    let num_events_field = Value::u64(num_events);
    Value::struct_(values::Struct::pack(vec![
        created_field,
        written_field,
        deleted_field,
        transferred_to_account_field,
        transferred_to_object_field,
        shared_field,
        frozen_field,
        num_events_field,
    ]))
}

fn pack_option(opt: Option<Value>) -> Value {
    let item = match opt {
        Some(v) => vec![v],
        None => vec![],
    };
    Value::struct_(values::Struct::pack(vec![Value::vector_for_testing_only(
        item,
    )]))
}

fn find_all_wrapped_objects<'a, 'i>(
    context: &NativeContext,
    ids: &'i mut BTreeSet<ObjectID>,
    new_object_values: impl IntoIterator<Item = (&'a ObjectID, &'a Type, impl Borrow<Value>)>,
) {
    #[derive(Copy, Clone)]
    enum LookingFor {
        Wrapped,
        Uid,
        Address,
    }

    struct Traversal<'i, 'u> {
        state: LookingFor,
        ids: &'i mut BTreeSet<ObjectID>,
        uid: &'u MoveStructLayout,
    }

    impl<'b, 'l> AV::Traversal<'b, 'l> for Traversal<'_, '_> {
        type Error = AV::Error;

        fn traverse_struct(
            &mut self,
            driver: &mut AV::StructDriver<'_, 'b, 'l>,
        ) -> Result<(), Self::Error> {
            match self.state {
                // We're at the top-level of the traversal, looking for an object to recurse into.
                // We can unconditionally switch to looking for UID fields at the level below,
                // because we know that all the top-level values are objects.
                LookingFor::Wrapped => {
                    while driver
                        .next_field(&mut Traversal {
                            state: LookingFor::Uid,
                            ids: self.ids,
                            uid: self.uid,
                        })?
                        .is_some()
                    {}
                }

                // We are looking for UID fields. If we find one (which we confirm by checking its
                // layout), switch to looking for addresses in its sub-structure.
                LookingFor::Uid => {
                    while let Some(MoveFieldLayout { name: _, layout }) = driver.peek_field() {
                        if matches!(layout, MoveTypeLayout::Struct(s) if s.as_ref() == self.uid) {
                            driver.next_field(&mut Traversal {
                                state: LookingFor::Address,
                                ids: self.ids,
                                uid: self.uid,
                            })?;
                        } else {
                            driver.next_field(self)?;
                        }
                    }
                }

                // When looking for addresses, recurse through structs, as the address is nested
                // within the UID.
                LookingFor::Address => while driver.next_field(self)?.is_some() {},
            }

            Ok(())
        }

        fn traverse_address(
            &mut self,
            _: &AV::ValueDriver<'_, 'b, 'l>,
            address: AccountAddress,
        ) -> Result<(), Self::Error> {
            // If we're looking for addresses, and we found one, then save it.
            if matches!(self.state, LookingFor::Address) {
                self.ids.insert(address.into());
            }
            Ok(())
        }
    }

    let uid = UID::layout();
    for (_id, ty, value) in new_object_values {
        let Ok(Some(layout)) = context.type_to_type_layout(ty) else {
            debug_assert!(false);
            continue;
        };

        let Ok(Some(annotated_layout)) = context.type_to_fully_annotated_layout(ty) else {
            debug_assert!(false);
            continue;
        };

        let blob = value.borrow().simple_serialize(&layout).unwrap();
        MoveValue::visit_deserialize(
            &blob,
            &annotated_layout,
            &mut Traversal {
                state: LookingFor::Wrapped,
                ids,
                uid: &uid,
            },
        )
        .unwrap();
    }
}