如何在Kotlin对象单例类中测试add方法

Question

我试图在我的object kotlin类中做一些测试，但是当我试图传递对象时，我的thenReturn方法中可能会出现一个错误。我得到一个要求：单位！找到结账。有人能告诉我怎么可能测试它？？

如果移除enreturn方法，则会出现以下错误：

Hints:
 1. missing thenReturn()
 2. you are trying to stub a final method, which is not supported
 3: you are stubbing the behaviour of another mock inside before 'thenReturn' instruction if completed

我引用了这个链接，但我不能得到它。

object CheckoutRepository: CheckoutContract.Model {

    var checkout: MutableList<Checkout> = mutableListOf<Checkout>()

    override fun addProductToShoppingCart(checkoutProduct: Checkout){
        checkout.add(checkoutProduct)
    }

    override fun getProductsInShoppinCart() : List<Checkout>?{
        return checkout
    }

    override fun cleanCheckout(){
        checkout.clear()
    }
}



@Test
    fun test_with_mock() {
        val mock = mock<CheckoutContract.Model>()

        var checkout = Checkout("VOUCHER", "voucher", 35.0, 5)
        mock.addProductToShoppingCart(checkout)

        val answer = mock.getProductsInShoppinCart()
        `when`(mock.addProductToShoppingCart(checkout)).thenReturn(checkout)

        assertNotNull(checkout)
        assertEquals(checkout, answer)
    }

Answer 1

在函数addProductToShoppingCart中没有任何返回类型。

如果您想要check Checkout类在函数中进行更改，那么测试用例将通过

override fun addProductToShoppingCart(checkoutProduct: Checkout):Checkout{
    checkout.add(checkoutProduct)
return checkout
}