你如何在 GoLang 的模拟中模拟错误返回值？

Posted 2023-03-25

【中文标题】你如何在 GoLang 的模拟中模拟错误返回值？

【英文标题】：How do you mock an error return value in mockery for GoLang?

【发布时间】：2020-02-20 22:40:46

【问题描述】：

我正在使用https://github.com/vektra/mockery 来生成我的模拟文件。

假设我对函数 GetQualifyingListOfBooks 进行了此测试。 （模拟的）客户端方法GetListOfBooks 的签名是：

func GetListOfBooks(ctx context.Context, in *GetListOfBooksRequest, opts ...grpc.CallOption) (*GetListOfBooksResponse, error)

目标：我想模拟GetListOfBooks返回错误的情况，所以我写了如下：

package whatever

import (
    "context"
    "testing"
    "github.com/stretchr/testify/assert"
    mock "github.com/stretchr/testify/mock"
    mockClients "github.com/MyOrg/MyApp/internal/app/myservice/mocks"
)

func TestGetQualifyingListOfBooks (t *testing.T) 
    client := &mockClients.BookClient
    client.On("GetListOfBooks", mock.Anything, mock.Anything).Return(nil, mock.AnythingOfType("error"))
    realInstance.bookClient = client
    b, err := GetQualifyingListOfBooks(realInstance, 10) // this calls `GetListOfBooks`
    assert.Nil(t, b)
    assert.NotNil(t, err)

但它对此感到恐慌：

--- FAIL: TestGetQualifyingListOfBooks (0.00s)
panic: assert: arguments: Error(1) failed because object wasn't correct type: Error(1) [recovered]
    panic: assert: arguments: Error(1) failed because object wasn't correct type: Error(1)

如何模拟错误的返回值？

【参考方案1】：

改变这一行

client.On("GetListOfBooks", mock.Anything, mock.Anything).Return(nil, mock.AnythingOfType("error"))

到这里

client.On("GetListOfBooks", mock.Anything, mock.Anything).Return(nil, errors.New("hello world"))

为我做的。

【讨论】：

似乎很单调