How to write test cases for golang functions?

Writing functional test cases in Go involves using the testing package, which provides functions for defining test cases (func Test) and reporting failures (t.Error). Unit tests test individual functions in isolation, while integration tests focus on interactions with other components. The sample test cases show how to use the testing package to define test functions, define input and output test cases, verify the results, and run them using the go test command.

Guidelines for writing function test cases in Go

When writing Go code, writing test cases is crucial to ensure that the code is robust and correct. Below is a guide to writing functional test cases, including practical examples using the Go language.

1. Unit Testing vs Integration Testing

When testing functions, there are two main types:

• Unit testing : Test the isolation behavior of a single function.
• Integration testing: Test how a function interacts with other components in the larger system.

2. Using Go’s testing package

The standard library in the Go language for writing test cases is testing Bag. This package provides some useful functions and types, such as:

• func Test(t *testing.T): Define a test case.
• t.Error(): Report test failure.
• t.Fail(): Fail the test immediately.
• t.Skip(): Skip the current test.

3. Write a test case

The following is an example of writing a function test case:

package main

import "testing"

// myFunc 是要测试的函数
func myFunc(x int) int {
    return x * x
}

// TestMyFunc 测试 myFunc 函数
func TestMyFunc(t *testing.T) {
    // 定义测试用例
    tests := []struct {
        input int
        expected int
    }{
        {0, 0},
        {1, 1},
        {2, 4},
        {3, 9},
        {-1, 1},
    }

    for _, tc := range tests {
        // 调用正在测试的函数
        result := myFunc(tc.input)

        // 验证结果
        if result != tc.expected {
            t.Errorf("Test failed. Expected: %d, Got: %d", tc.expected, result)
        }
    }
}

4. Run Test case

You can use the following command to run the test case:

go test

5. Practical case

Consider a calculation that calculates the sum of elements in a list Function:

func sum(nums []int) int {
    sum := 0
    for _, num := range nums {
        sum += num
    }
    return sum
}

The following are some test cases:

func TestSum(t *testing.T) {
    tests := []struct {
        input []int
        expected int
    }{
        {[]int{}, 0},
        {[]int{1}, 1},
        {[]int{1, 2}, 3},
        {[]int{1, 2, 3}, 6},
        {[]int{-1, 0, 1}, 0},
    }

    for _, tc := range tests {
        result := sum(tc.input)

        if result != tc.expected {
            t.Errorf("Test failed. Expected: %d, Got: %d", tc.expected, result)
        }
    }
}

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