describe('exchangeRateUpdate functionality', function() {
    const axios = require('axios');
    const models = require('vn-loopback/server/server').models;

    beforeEach(function() {
        spyOn(axios, 'get').and.returnValue(Promise.resolve({
            data: `<Cube>
                    <Cube time='2024-04-12'>
                        <Cube currency='USD' rate='1.1'/>
                        <Cube currency='CNY' rate='1.2'/>
                    </Cube>
                </Cube>`
        }));
    });

    it('should process XML data and update or create rates in the database', async function() {
        spyOn(models.ReferenceRate, 'findOne').and.returnValue(Promise.resolve(null));
        spyOn(models.ReferenceRate, 'create').and.returnValue(Promise.resolve());

        await models.InvoiceIn.exchangeRateUpdate();

        expect(models.ReferenceRate.create).toHaveBeenCalledTimes(2);
    });

    it('should not create or update rates when no XML data is available', async function() {
        axios.get.and.returnValue(Promise.resolve({}));
        spyOn(models.ReferenceRate, 'create');

        let thrownError = null;
        try {
            await models.InvoiceIn.exchangeRateUpdate();
        } catch (error) {
            thrownError = error;
        }

        expect(thrownError.message).toBe('No cubes found. Exiting the method.');
    });

    it('should handle errors gracefully', async function() {
        axios.get.and.returnValue(Promise.reject(new Error('Network error')));
        let error;

        try {
            await models.InvoiceIn.exchangeRateUpdate();
        } catch (e) {
            error = e;
        }

        expect(error).toBeDefined();
        expect(error.message).toBe('Network error');
    });
});