//! Compile here; execute only in the designated remote validation environment.
use endor_core::{
    AnnotationType as T, CallEffect, CallSignature, CallType, CodeLayout, ContextNativeFunction,
    EndorCode, Instruction, NativeCallable, NativeContext, NativeResult, ObjectRef, Opcode,
    SourceSignature, TypeConstructor, Value, Vm, VmError,
};
use std::collections::BTreeMap;

fn source(
    vm: &mut Vm,
    globals: ObjectRef,
    owner: &str,
    parameters: &[&str],
    returns: &str,
    result: Value,
) -> ObjectRef {
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadConst, 0),
            Instruction::new(Opcode::StoreGlobal, 0),
            Instruction::new(Opcode::LoadConst, 1),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![Value::Number(42.into()), result],
        CodeLayout {
            parameters: (0..parameters.len()).map(|i| format!("p{i}")).collect(),
            locals: (0..parameters.len()).map(|i| format!("p{i}")).collect(),
            names: vec!["ran".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap()
    .with_source_signature(SourceSignature {
        parameters: parameters.iter().map(|s| (*s).into()).collect(),
        return_type: returns.into(),
        method_owner: Some(owner.into()),
    })
    .unwrap();
    let code = vm.new_code(code).unwrap();
    let function = vm
        .new_function("check", code, globals, vec![], vec![])
        .unwrap();
    vm.release(code).unwrap();
    function
}
fn class(
    vm: &mut Vm,
    name: &str,
    base: ObjectRef,
    function: ObjectRef,
) -> Result<ObjectRef, VmError> {
    vm.new_class(
        name,
        base,
        vec![],
        BTreeMap::from([("check".into(), function)]),
    )
}

#[test]
fn source_parameters_are_contravariant_and_returns_covariant_at_class_creation() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let globals = vm.new_dict().unwrap();
    let base_fn = source(
        &mut vm,
        globals,
        "Base",
        &["Base", "Number"],
        "Object",
        Value::Nil,
    );
    let base = class(&mut vm, "Base", roots.object, base_fn).unwrap();
    let good_fn = source(
        &mut vm,
        globals,
        "Good",
        &["Good", "Object"],
        "Number",
        Value::Number(7.into()),
    );
    let good = class(&mut vm, "Good", base, good_fn).unwrap();
    let narrow = source(
        &mut vm,
        globals,
        "Narrow",
        &["Narrow", "String"],
        "Number",
        Value::Nil,
    );
    assert!(matches!(
        class(&mut vm, "Narrow", base, narrow),
        Err(VmError::OverrideViolation {
            reason: "override narrows a parameter type",
            ..
        })
    ));
    let numeric = source(
        &mut vm,
        globals,
        "Numeric",
        &["Numeric", "Object"],
        "Number",
        Value::Number(0.into()),
    );
    let numeric_type = class(&mut vm, "Numeric", roots.object, numeric).unwrap();
    let broad = source(
        &mut vm,
        globals,
        "Broad",
        &["Broad", "Object"],
        "Object",
        Value::Nil,
    );
    assert!(matches!(
        class(&mut vm, "Broad", numeric_type, broad),
        Err(VmError::OverrideViolation {
            reason: "override widens the return type",
            ..
        })
    ));
    for object in [
        good,
        good_fn,
        narrow,
        broad,
        numeric_type,
        numeric,
        base,
        base_fn,
        globals,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn replacing_an_ancestor_validates_overriding_descendants_before_mutation() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let globals = vm.new_dict().unwrap();
    let base_fn = source(
        &mut vm,
        globals,
        "Base",
        &["Base", "Number"],
        "Object",
        Value::Nil,
    );
    let base = class(&mut vm, "Base", roots.object, base_fn).unwrap();
    let child_fn = source(
        &mut vm,
        globals,
        "Child",
        &["Child", "Number"],
        "Number",
        Value::Number(0.into()),
    );
    let child = class(&mut vm, "Child", base, child_fn).unwrap();
    let replacement = source(
        &mut vm,
        globals,
        "Base",
        &["Base", "Object"],
        "Object",
        Value::Nil,
    );
    let version = vm.change_version(base).unwrap();
    assert!(matches!(
        vm.define_method(base, "check", replacement),
        Err(VmError::OverrideViolation { .. })
    ));
    assert_eq!(vm.change_version(base).unwrap(), version);
    assert_eq!(
        vm.object_store().lookup_method(base, "check").unwrap(),
        Some(base_fn)
    );
    assert_eq!(
        vm.object_store().lookup_method(child, "check").unwrap(),
        Some(child_fn)
    );
    for object in [
        replacement,
        child,
        child_fn,
        base,
        base_fn,
        globals,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn global_rebinding_is_rechecked_before_the_source_body_and_recovers() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let parent = vm
        .new_type("Result", roots.object, TypeConstructor::Record)
        .unwrap();
    let result_type = vm
        .new_type("ResultChild", parent, TypeConstructor::Record)
        .unwrap();
    let other = vm
        .new_type("Other", roots.object, TypeConstructor::Record)
        .unwrap();
    let result = vm.new_object().unwrap();
    vm.attach_type(result, result_type).unwrap();
    let base_globals = vm.new_dict().unwrap();
    let globals = vm.new_dict().unwrap();
    vm.dict_set(
        base_globals,
        Value::Text("Result".into()),
        Value::Object(parent),
    )
    .unwrap();
    vm.dict_set(
        globals,
        Value::Text("Actual".into()),
        Value::Object(result_type),
    )
    .unwrap();
    vm.dict_set(globals, Value::Text("ran".into()), Value::Number(0.into()))
        .unwrap();
    let base_fn = source(
        &mut vm,
        base_globals,
        "Base",
        &["Base"],
        "Result",
        Value::Nil,
    );
    let base = class(&mut vm, "Base", roots.object, base_fn).unwrap();
    let child_fn = source(
        &mut vm,
        globals,
        "Child",
        &["Child"],
        "Actual",
        Value::Object(result),
    );
    let child = class(&mut vm, "Child", base, child_fn).unwrap();
    let receiver = vm.new_object().unwrap();
    vm.attach_type(receiver, child).unwrap();
    vm.dict_set(globals, Value::Text("Actual".into()), Value::Object(other))
        .unwrap();
    assert!(matches!(
        vm.call(child_fn, &[Value::Object(receiver)]),
        Err(VmError::OverrideViolation { .. })
    ));
    assert_eq!(
        vm.dict_get(globals, &Value::Text("ran".into())).unwrap(),
        Some(Value::Number(0.into()))
    );
    vm.dict_set(
        globals,
        Value::Text("Actual".into()),
        Value::Object(result_type),
    )
    .unwrap();
    let value = vm.call(child_fn, &[Value::Object(receiver)]).unwrap();
    assert_eq!(value, Value::Object(result));
    vm.release_value(value).unwrap();
    for object in [
        receiver,
        child,
        child_fn,
        base,
        base_fn,
        globals,
        base_globals,
        result,
        other,
        result_type,
        parent,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[derive(Debug)]
struct Native(CallSignature);
impl NativeCallable for Native {
    fn signature(&self) -> Option<CallSignature> {
        Some(self.0.clone())
    }
    fn invoke(&self, _: &mut NativeContext<'_>, _: &[Value]) -> Result<NativeResult, VmError> {
        Ok(NativeResult::Return(Value::Number(0.into())))
    }
}
#[test]
fn native_overrides_preserve_union_inputs_and_do_not_expand_effects() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let base = vm
        .new_type("Base", roots.object, TypeConstructor::Record)
        .unwrap();
    let mut signature = CallSignature::exact(
        vec![T::Nominal(base), T::Any],
        T::Number,
        CallEffect::ReadOnly,
    );
    signature.parameters[1] = CallType::Union(vec![T::Number, T::String]);
    let base_fn = vm
        .allocate(ContextNativeFunction::new(
            "check",
            Native(signature),
            vec![],
        ))
        .unwrap();
    vm.define_method(base, "check", base_fn).unwrap();
    let child = vm.new_type("Child", base, TypeConstructor::Record).unwrap();
    let effect_fn = vm
        .allocate(ContextNativeFunction::new(
            "effect",
            Native(CallSignature::exact(
                vec![T::Nominal(child), T::Any],
                T::Number,
                CallEffect::Mutating,
            )),
            vec![],
        ))
        .unwrap();
    assert!(matches!(
        vm.define_method(child, "check", effect_fn),
        Err(VmError::OverrideViolation {
            reason: "override expands known effects",
            ..
        })
    ));
    let narrow_fn = vm
        .allocate(ContextNativeFunction::new(
            "narrow",
            Native(CallSignature::exact(
                vec![T::Nominal(child), T::Number],
                T::Number,
                CallEffect::ReadOnly,
            )),
            vec![],
        ))
        .unwrap();
    assert!(matches!(
        vm.define_method(child, "check", narrow_fn),
        Err(VmError::OverrideViolation {
            reason: "override narrows a parameter type",
            ..
        })
    ));
    for object in [
        narrow_fn,
        effect_fn,
        child,
        base_fn,
        base,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn unknown_forward_names_defer_until_call_without_entering_the_body() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let globals = vm.new_dict().unwrap();
    vm.dict_set(globals, Value::Text("ran".into()), Value::Number(0.into()))
        .unwrap();
    let base_fn = source(
        &mut vm,
        globals,
        "Base",
        &["Base", "Number"],
        "Number",
        Value::Number(0.into()),
    );
    let base = class(&mut vm, "Base", roots.object, base_fn).unwrap();
    let child_fn = source(
        &mut vm,
        globals,
        "Child",
        &["Child", "Later"],
        "Number",
        Value::Number(0.into()),
    );
    let child = class(&mut vm, "Child", base, child_fn).unwrap();
    let receiver = vm.new_object().unwrap();
    vm.attach_type(receiver, child).unwrap();
    assert!(matches!(
        vm.call(
            child_fn,
            &[Value::Object(receiver), Value::Number(1.into())]
        ),
        Err(VmError::UnknownAnnotation(_))
    ));
    let later = vm
        .new_type("Later", roots.object, TypeConstructor::Record)
        .unwrap();
    vm.dict_set(globals, Value::Text("Later".into()), Value::Object(later))
        .unwrap();
    assert!(matches!(
        vm.call(
            child_fn,
            &[Value::Object(receiver), Value::Number(1.into())]
        ),
        Err(VmError::OverrideViolation { .. })
    ));
    assert_eq!(
        vm.dict_get(globals, &Value::Text("ran".into())).unwrap(),
        Some(Value::Number(0.into()))
    );
    for object in [
        receiver,
        child,
        child_fn,
        base,
        base_fn,
        later,
        globals,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn verified_source_read_only_effects_constrain_native_overrides() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    vm.set_source_type_checks(true).unwrap();
    let globals = vm.new_dict().unwrap();
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadFast, 1),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            parameters: vec!["self".into(), "value".into()],
            locals: vec!["self".into(), "value".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap()
    .with_source_signature(SourceSignature {
        parameters: vec!["PureBase".into(), "Number".into()],
        return_type: "Number".into(),
        method_owner: Some("PureBase".into()),
    })
    .unwrap();
    assert!(code.is_statically_read_only());
    let code = vm.new_code(code).unwrap();
    let source = vm
        .new_function("check", code, globals, vec![], vec![])
        .unwrap();
    let base = class(&mut vm, "PureBase", roots.object, source).unwrap();
    let child = vm.new_type("Child", base, TypeConstructor::Record).unwrap();
    assert_eq!(vm.call_effect(source).unwrap(), Some(CallEffect::ReadOnly));
    let receiver = vm.new_object().unwrap();
    vm.attach_type(receiver, child).unwrap();
    let Value::Object(bound) = vm.bind_attr(receiver, "check").unwrap() else {
        panic!("bound method")
    };
    assert_eq!(vm.call_effect(bound).unwrap(), Some(CallEffect::ReadOnly));
    let mut functions = vec![];
    for effect in [
        CallEffect::Mutating,
        CallEffect::External,
        CallEffect::ReadOnly,
        CallEffect::Delegated,
    ] {
        let function = vm
            .allocate(ContextNativeFunction::new(
                "check",
                Native(CallSignature::exact(
                    vec![T::Any, T::Number],
                    T::Number,
                    effect,
                )),
                vec![],
            ))
            .unwrap();
        let version = vm.change_version(child).unwrap();
        let update = vm.define_method(child, "check", function);
        if matches!(effect, CallEffect::Mutating | CallEffect::External) {
            assert!(matches!(
                update,
                Err(VmError::OverrideViolation {
                    reason: "override expands known effects",
                    ..
                })
            ));
            assert_eq!(vm.change_version(child).unwrap(), version);
        } else {
            update.unwrap();
        }
        assert_eq!(
            vm.call_effect(function).unwrap(),
            (effect != CallEffect::Delegated).then_some(effect)
        );
        functions.push(function);
    }
    for object in functions.into_iter().chain([
        bound,
        receiver,
        child,
        base,
        source,
        code,
        globals,
        roots.object,
        roots.type_type,
    ]) {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn shared_local_assignment_and_dynamic_calls_are_not_inferred_pure() {
    let assignment = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadFast, 1),
            Instruction::new(Opcode::StoreFast, 0),
            Instruction::new(Opcode::LoadFast, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            parameters: vec!["target".into(), "value".into()],
            locals: vec!["target".into(), "value".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    assert!(!assignment.is_statically_read_only());
    let captured = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadConst, 0),
            Instruction::new(Opcode::StoreDeref, 0),
            Instruction::new(Opcode::LoadConst, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![Value::Nil],
        CodeLayout {
            free_variables: vec!["captured".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    assert!(!captured.is_statically_read_only());
    let call = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadGlobal, 0),
            Instruction::simple(Opcode::PushNull),
            Instruction::new(Opcode::Call, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            names: vec!["dynamic".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    assert!(!call.is_statically_read_only());
}

fn global_caller(vm: &mut Vm, globals: ObjectRef, name: &str) -> ObjectRef {
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadGlobal, 0),
            Instruction::simple(Opcode::PushNull),
            Instruction::new(Opcode::Call, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            names: vec![name.into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    let code = vm.new_code(code).unwrap();
    let function = vm
        .new_function("caller", code, globals, vec![], vec![])
        .unwrap();
    vm.release(code).unwrap();
    function
}

#[test]
fn transitive_effect_queries_follow_rebinding_closures_and_recursive_graphs() {
    let mut vm = Vm::new().unwrap();
    let globals = vm.new_dict().unwrap();
    let builtins = vm.new_dict().unwrap();
    vm.dict_set(
        globals,
        Value::Text("__builtins__".into()),
        Value::Object(builtins),
    )
    .unwrap();
    let pure = vm
        .allocate(ContextNativeFunction::new(
            "pure",
            Native(CallSignature::exact(
                vec![],
                T::Number,
                CallEffect::ReadOnly,
            )),
            vec![],
        ))
        .unwrap();
    let impure = vm
        .allocate(ContextNativeFunction::new(
            "impure",
            Native(CallSignature::exact(
                vec![],
                T::Number,
                CallEffect::Mutating,
            )),
            vec![],
        ))
        .unwrap();
    vm.dict_set(builtins, Value::Text("target".into()), Value::Object(pure))
        .unwrap();
    let wrapper = global_caller(&mut vm, globals, "target");
    let outer = global_caller(&mut vm, globals, "wrapper");
    vm.dict_set(
        globals,
        Value::Text("wrapper".into()),
        Value::Object(wrapper),
    )
    .unwrap();
    assert_eq!(vm.call_effect(outer).unwrap(), Some(CallEffect::ReadOnly));
    vm.dict_set(globals, Value::Text("target".into()), Value::Object(impure))
        .unwrap();
    assert_eq!(vm.call_effect(outer).unwrap(), None);
    vm.dict_delete(globals, &Value::Text("target".into()))
        .unwrap();
    assert_eq!(vm.call_effect(outer).unwrap(), Some(CallEffect::ReadOnly));
    let cell = vm.new_cell(Some(Value::Object(pure))).unwrap();
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadDeref, 0),
            Instruction::simple(Opcode::PushNull),
            Instruction::new(Opcode::Call, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            free_variables: vec!["target".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    let code = vm.new_code(code).unwrap();
    let closure = vm
        .new_function("closure", code, globals, vec![], vec![cell])
        .unwrap();
    assert_eq!(vm.call_effect(closure).unwrap(), Some(CallEffect::ReadOnly));
    vm.cell_set(cell, Value::Object(impure)).unwrap();
    assert_eq!(vm.call_effect(closure).unwrap(), None);
    vm.cell_set(cell, Value::Object(pure)).unwrap();
    assert_eq!(vm.call_effect(closure).unwrap(), Some(CallEffect::ReadOnly));
    let recursive = global_caller(&mut vm, globals, "recursive");
    vm.dict_set(
        globals,
        Value::Text("recursive".into()),
        Value::Object(recursive),
    )
    .unwrap();
    // No function body is executed, including this non-terminating call graph.
    assert_eq!(
        vm.call_effect(recursive).unwrap(),
        Some(CallEffect::ReadOnly)
    );
    vm.dict_set(
        globals,
        Value::Text("recursive".into()),
        Value::Object(impure),
    )
    .unwrap();
    assert_eq!(vm.call_effect(recursive).unwrap(), None);
    for object in [
        recursive, closure, code, cell, outer, wrapper, pure, impure, builtins, globals,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn effect_control_flow_joins_do_not_keep_a_stale_known_call_target() {
    let mut vm = Vm::new().unwrap();
    let globals = vm.new_dict().unwrap();
    let pure = vm
        .allocate(ContextNativeFunction::new(
            "pure",
            Native(CallSignature::exact(
                vec![],
                T::Number,
                CallEffect::ReadOnly,
            )),
            vec![],
        ))
        .unwrap();
    let impure = vm
        .allocate(ContextNativeFunction::new(
            "impure",
            Native(CallSignature::exact(
                vec![],
                T::Number,
                CallEffect::External,
            )),
            vec![],
        ))
        .unwrap();
    for name in ["left", "right"] {
        vm.dict_set(globals, Value::Text(name.into()), Value::Object(pure))
            .unwrap();
    }
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadFast, 0),
            Instruction::new(Opcode::PopJumpIfFalse, 2),
            Instruction::new(Opcode::LoadGlobal, 0),
            Instruction::new(Opcode::JumpForward, 1),
            Instruction::new(Opcode::LoadGlobal, 1),
            Instruction::simple(Opcode::PushNull),
            Instruction::new(Opcode::Call, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            parameters: vec!["condition".into()],
            locals: vec!["condition".into()],
            names: vec!["left".into(), "right".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    let code = vm.new_code(code).unwrap();
    let function = vm
        .new_function("choose", code, globals, vec![], vec![])
        .unwrap();
    assert_eq!(
        vm.call_effect(function).unwrap(),
        Some(CallEffect::ReadOnly)
    );
    vm.dict_set(globals, Value::Text("right".into()), Value::Object(impure))
        .unwrap();
    assert_eq!(vm.call_effect(function).unwrap(), None);
    vm.dict_set(globals, Value::Text("right".into()), Value::Object(pure))
        .unwrap();
    assert_eq!(
        vm.call_effect(function).unwrap(),
        Some(CallEffect::ReadOnly)
    );
    for object in [function, code, pure, impure, globals] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}

#[test]
fn bound_source_effects_follow_the_actual_receiver_method_and_instance_field() {
    let mut vm = Vm::new().unwrap();
    let roots = vm.bootstrap_types().unwrap();
    let globals = vm.new_dict().unwrap();
    let definition = vm
        .new_type("Receiver", roots.object, TypeConstructor::Record)
        .unwrap();
    let pure = vm
        .allocate(ContextNativeFunction::new(
            "helper",
            Native(CallSignature::exact(
                vec![T::Any],
                T::Number,
                CallEffect::ReadOnly,
            )),
            vec![],
        ))
        .unwrap();
    let impure = vm
        .allocate(ContextNativeFunction::new(
            "helper",
            Native(CallSignature::exact(
                vec![T::Any],
                T::Number,
                CallEffect::Mutating,
            )),
            vec![],
        ))
        .unwrap();
    let code = EndorCode::from_instructions(
        &[
            Instruction::new(Opcode::LoadFast, 0),
            Instruction::new(Opcode::LoadAttr, 0),
            Instruction::simple(Opcode::PushNull),
            Instruction::new(Opcode::Call, 0),
            Instruction::simple(Opcode::ReturnValue),
        ],
        vec![],
        CodeLayout {
            parameters: vec!["self".into()],
            locals: vec!["self".into()],
            names: vec!["helper".into()],
            ..CodeLayout::default()
        },
    )
    .unwrap();
    let code = vm.new_code(code).unwrap();
    let function = vm
        .new_function("check", code, globals, vec![], vec![])
        .unwrap();
    vm.define_method(definition, "helper", pure).unwrap();
    vm.define_method(definition, "check", function).unwrap();
    let receiver = vm.new_object().unwrap();
    vm.attach_type(receiver, definition).unwrap();
    let Value::Object(bound) = vm.bind_attr(receiver, "check").unwrap() else {
        panic!("bound")
    };
    assert_eq!(vm.call_effect(function).unwrap(), None);
    assert_eq!(vm.call_effect(bound).unwrap(), Some(CallEffect::ReadOnly));
    vm.define_method(definition, "helper", impure).unwrap();
    assert_eq!(vm.call_effect(bound).unwrap(), None);
    vm.define_method(definition, "helper", pure).unwrap();
    assert_eq!(vm.call_effect(bound).unwrap(), Some(CallEffect::ReadOnly));
    vm.set_attr(receiver, "helper", Value::Object(impure))
        .unwrap();
    assert_eq!(vm.call_effect(bound).unwrap(), None);
    vm.del_attr(receiver, "helper").unwrap();
    assert_eq!(vm.call_effect(bound).unwrap(), Some(CallEffect::ReadOnly));
    for object in [
        bound,
        receiver,
        function,
        code,
        pure,
        impure,
        definition,
        globals,
        roots.object,
        roots.type_type,
    ] {
        vm.release(object).unwrap();
    }
    vm.collect_cycles();
    assert_eq!(vm.object_count(), 0);
}