Unit testing of golang function types

Unit testing of function types in the Go language requires constructing a Mock function to simulate function parameters or return values, and then using assertions to verify whether the Mock function is called correctly and has the expected behavior: Construct a Mock function: Create a replacement function to simulate a specific function and replace it with the actual function. Test function type parameters: Use the Mock function to call a function with a function type as a parameter and assert that the incoming function parameters are called correctly. Test the return value of the function type: Write a helper function to call the function under test and return the function type it returns. Use the Mock function to verify whether the returned function type has the expected behavior.

Go language function type unit test

In Go language, function type refers to a function that can be used as a parameter or returned The function type of the value. When unit testing such functions, additional measures need to be taken.

Constructing Mock function

Mock function is a substitute function used to simulate a specific function or behavior. When testing function types, we can create a Mock function to simulate the parameters passed into or returned from the function.

package function_test

import (
    "testing"
)

// 定义要测试的函数类型
type Greeter func(name string) string

// 创建 Mock Greeter 函数
func MockGreeter(name string) string {
    return "你好，" + name + "！"
}

Testing parameters of function type

To test a function with a function type as a parameter, you need to use a Mock function to replace the actual function and assert that the incoming function parameters are called correctly .

func TestGreet(t *testing.T) {
    // 创建一个函数类型，使用 Mock Greeter 函数
    greet := func(greeter Greeter) string {
        return greeter("Alice")
    }

    // 调用 greet 函数并断言返回的文本正确
    result := greet(MockGreeter)
    if result != "你好，Alice！" {
        t.Errorf("Expected '你好，Alice！' but got '%s'", result)
    }
}

Testing the return value of a function type

To test a function with a function type as a return value, you need to write a helper function that calls the function under test and returns the function type. You can then use the Mock function to verify that the returned function type has the expected behavior.

func TestGetGreeter(t *testing.T) {
    // 创建一个函数类型，返回一个 Greeter 函数
    getGreeter := func() Greeter {
        return func(name string) string {
            return "你好，" + name + "！"
        }
    }

    // 获取返回的 Greeter 函数并将其传递给 Mock 函数
    greeter := getGreeter()
    result := MockGreeter(greeter("Bob"))

    // 断言 MockGreeter 调用时返回了预期的文本
    if result != "你好，Bob！" {
        t.Errorf("Expected '你好，Bob！' but got '%s'", result)
    }
}

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