Question

我正在编写单元测试，并且我想编写一个单元测试来断言结构（Foo.Start）上的公共方法正确处理了结构（{{1}）上来自内部方法的错误响应}。

基本上，我想对我的代码这一部分进行测试：

Foo.internal

这是一个不起作用的代码和相关测试的示例（但在Python中会起作用）

if err != nil {
    return err
}

# example.go

package example

import "fmt"

type FooAPI interface {
    Start() error
    internal(string) (string, error)
}

type Foo struct {
    FooAPI
}

func (foo Foo) Start() (err error) {

    data, err := foo.internal("bar")
    if err != nil {
        return err
    }

    fmt.Println(data)
    return err
}

func (foo Foo) internal(input string) (output string, err error) {
    return output, err
}

我对更正特定示例的兴趣不大，因此我的目标是对# example_test.go package example import ( "testing" "github.com/pkg/errors" ) type MockFoo struct { FooAPI } func (foo MockFoo) internal(input string) (output string, err error) { return output, errors.New("big error") } func TestStart(t *testing.T) { tdata := []struct { testCase string expectedAnError bool foo FooAPI }{ { testCase: "standard_case", expectedAnError: false, foo: Foo{}, }, { testCase: "error_case", expectedAnError: true, foo: MockFoo{}, }, } for _, test := range tdata { t.Run(test.testCase, func(t *testing.T) { // The function under test test.foo.Start = Foo.Start // <= this doesn't work err := test.foo.Start() // Assertion 1 if test.expectedAnError == false && err != nil { t.Error(err.Error()) } // Assertion 2 if test.expectedAnError == true && err == nil { t.Error("expected an error, but there was none!") } }) } }的错误处理进行测试。我觉得接口或指针有一些技巧可以使我在终点线？

Answer 1

我想出了一个受https://stackoverflow.com/a/48206430/3055558启发的解决方案

使用internal{{ your struct }}结构和关联的接口，并对其进行模拟。

# example.go

package example

import "fmt"

type internalFooAPI interface {
    internalBehavior(string) (string, error)
}

type Foo struct {
    internal internalFooAPI
}

type internalFoo struct{}

func NewFoo(internal internalFooAPI) Foo {
    return Foo{
        internal: internal,
    }
}

func (foo Foo) Start() (err error) {

    data, err := foo.internal.internalBehavior("bar")
    if err != nil {
        return err
    }

    fmt.Println(data)
    return err
}

func (foo internalFoo) internalBehavior(input string) (output string, err error) {
    return output, err
}

# example_test.go

package example

import (
    "testing"

    "github.com/pkg/errors"
)

type mockInternalFoo struct{}

type mockInternalFooWithErrors struct{}

func (foo mockInternalFoo) internalBehavior(input string) (output string, err error) {
    return output, err
}

func (foo mockInternalFooWithErrors) internalBehavior(input string) (output string, err error) {
    return output, errors.New("big error")
}

func TestStart(t *testing.T) {
    tdata := []struct {
        testCase        string
        expectedAnError bool
        foo             Foo
    }{
        {
            testCase:        "standard_case",
            expectedAnError: false,
            foo:             NewFoo(internalFoo{}),
        },
        {
            testCase:        "mock_case",
            expectedAnError: false,
            foo:             NewFoo(mockInternalFoo{}),
        },
        {
            testCase:        "error_case",
            expectedAnError: true,
            foo:             NewFoo(mockInternalFooWithErrors{}),
        },
    }
    for _, test := range tdata {
        t.Run(test.testCase, func(t *testing.T) {
            // The function under test
            err := test.foo.Start()

            // Assertion 1
            if test.expectedAnError == false && err != nil {
                t.Error(err.Error())
            }

            // Assertion 2
            if test.expectedAnError == true && err == nil {
                t.Error("expected an error, but there was none!")
            }
        })
    }
}

用结构内部的方法测试错误响应

1 个答案: