项目目录结构

calcs.go源文件

package main

import (
    "fmt"
    "os"
    "strconv"
    "myapp/simplemath"
)

var Usage = func() {
    fmt.Println("USAGE: calcs command [arguments] ...")
    fmt.Println("\nThe commands are:\n\tadd\tAddition of two values.\n\tsqrt\tSquare root of a ono-negative value.")
}

func main()  {
    args := os.Args//接受命令行参数
    if args == nil || len(args) < 3 {
        Usage()
        return
    }

    switch args[1] {
    case "add":
        if len(args) != 4{
            fmt.Println("USAGE:calcs add <integer1> <interger2>")
            return
        }
        v1,err1 := strconv.Atoi(args[2])
        v2,err2 := strconv.Atoi(args[3])
        if err1 != nil || err2 != nil {
            fmt.Println("USAGE: calcs add <integer1> <integer2>")
            return
        }
        ret := simplemath.Add(v1,v2)
        fmt.Println("Result: ",ret)
    case "sqrt":
        if len(args) != 3 {
            fmt.Println("USAGE: calcs sqrt <integer>")
        }
        v , err := strconv.Atoi(args[2])
        if err != nil {
            fmt.Println("USAGE: calcs sqrt <integer>")
            return
        }
        ret := simplemath.Sqrt(v)
        fmt.Println("Result: ",ret)
    default:
        Usage()
    }
}

add.go源文件

package simplemath

func Add (a int,b int) int {
    return a + b
}

add_test.go源文件，测试程序

package simplemath

import "testing"

func TestAdd(t *testing.T) {
    r := Add(1,2)
    if r != 3 {
        t.Errorf("Add(1,2) failed. Got %d,expected 3.",r)
    }
    println(r)
}

sqrt.go源文件

package simplemath

import (
    "math"
)

func Sqrt(i int) int {
    v := math.Sqrt(float64(i))
    return int(v)
}

sqrt_test.go源文件，测试程序

package simplemath

import "testing"

func TestSqrt(t *testing.T) {
    v := Sqrt(16)
    if v != 4 {
        t.Errorf("Sqrt(16) failed. Got %v,expected 4.",v)
    }
    println(v)
}

然后编译calcs.go

测试结果