How to resolve Mirage mocking HasMany relationship error for Ember JS

Ember JS framework.

I am trying to test my route.js . I created route-test.js as below which is running fine but I need to use mirage mocking to mock foo model in route-test.js.

When I tried mocking, I got below error: Mirage: Error: You're trying to create a foo model and you passed in "[object Object],[object Object],[object Object]" under the boo key, but that key is a HasMany relationship. You must pass in a Collection, PolymorphicCollection, array of Models, or null.

Below are my code files:

// mirage/factories/foo.js

import { Factory, association } from 'ember-cli-mirage';

export default Factory.extend({
    isActive: true,
    user: association(),
});

// route-test.js:

test('model should return expected structure', async function (assert) {
        const foo = {
            boo: [
                { code: 'USD' },
                { code: 'EUR' },
                { code: 'USD' },
            ],
        };

        sinon
            .stub(this.route, 'modelFor')
            .withArgs('admin.foo.edit')
            .returns({ foo });

        const productClasses = [{ id: '1', name: 'class1' }];

        sinon
            .stub(this.store, 'query')
            .withArgs('product-class')
            .resolves(productClasses);

        const model = await this.route.model();

        assert.deepEqual(model.foo, foo, 'foo data is correct');
    });

// route.js:

async model() {
        const { foo } = this.modelFor('admin.foo.edit');
        const { foo } = this.modelFor(
            'admin.foo.edit'
        );

        let currencies = [];
        foo.boo.forEach(boo => {
            if (boo.code) {
                currencies = currencies.concat(
                    boo.code
                );
            }
        });
        uniqueCurrencies = [...new Set(currencies)];
        uniqueCurrencies.sort();

        const productClasses = await this.store.query('product-class');
        return hash({
            foo,
            productClasses,
            uniqueCurrencies,
        });
    }

I tried creating factory for boo as below, but got same error.

// mirage/factories/boo.js

import { Factory, association } from 'ember-cli-mirage';

export default Factory.extend({
    currencyCode(i) {
        return i % 2 === 0 ? 'USD' : 'EUR';
    },
    foo: association(),
});

Note: I am not using mirage models in my project so cannot use that.

Is there any other way to resolve this?