@ModelAttribute("product")
    public Product product(@PathVariable("productId") int productId) {
        return this.productsRestClient.findProduct(productId)
                .orElseThrow(() -> new NoSuchElementException("catalogue.errors.product.not_found"));
    }
@Test
    void product_ProductExists_ReturnsProduct() {
        // given
        var product = new Product(1, "Товар №1", "Описание товара №1");

        doReturn(Optional.of(product)).when(this.productsRestClient).findProduct(1);

        // when
        var result = this.controller.product(1);

        // then
        assertEquals(product, result);

        verify(this.productsRestClient).findProduct(1);
        verifyNoMoreInteractions(this.productsRestClient);
    }