drsxzut183207938 2014-12-03 17:26
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您如何测试golang命令行输出

I'd like to test the output of a golang command line app, but I'm not quite sure how to do that with go's testing library.

Let's say I have a program like this:

package main

import (
    "flag"
    "fmt"
)

func main() {
    const (
        cityDefault = "San Francisco"
        cityDoc     = "the city you want the forecast for"
    )
    var city string
    flag.StringVar(&city, "city", cityDefault, cityDoc)
    flag.StringVar(&city, "c", cityDefault, cityDoc)
    flag.Parse()

    fmt.Println(city)
}

I'd like to test that both of these:

$ ./myapp -c "Los Angeles"
$ ./myapp -city "Los Angeles"

... output Lost Angeles. So, I guess the question is, how do you go about integration testing the output of a golang command line app?

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  • doupang9080 2017-03-08 21:29
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    This is a bad example of parsing command line args, but it shows the framework I use to test command line args in my apps.

    main.go

    package main
    
    import (
        "log"
        "os"
    )
    
    func main() {
        var city string
        parseFlags(&city, os.Args)
    
        log.Println(city)
    }
    
    func parseFlags(result *string, args []string) {
        cityDefault := "San Francisco"
    
        switch len(args) {
        case 3:
            *result = args[2]
        default:
            *result = cityDefault
        }
    }
    

    main_unit_test.go

    package main
    
    import (
        "log"
        "testing"
    )
    
    // TestParseFlags - test our command line flags
    func TestParseFlags(t *testing.T) {
        var parseFlagsTests = []struct {
            flags    []string // input flags to the command line
            expected string   // expected
        }{
            {[]string{"/fake/loc/main"}, "San Francisco"},
            {[]string{"/fake/loc/main", "-c", "Los Angeles"}, "Los Angeles"},
            {[]string{"/fake/loc/main", "--city", "Los Angeles"}, "Los Angeles"},
        }
    
        for _, tt := range parseFlagsTests {
            var output string
            parseFlags(&output, tt.flags)
            if output != tt.expected {
                t.Errorf("expected: %s, actual: %s", tt.expected, output)
            }
        }
    }
    

    I typically use this package to parse command line args in all of my apps. And I'll structure my code as follows (tests not shown, but they generally follow the gist of the test shown above):

    main.go

    package main
    
    import (
        "log"
        "os"
    
        "myDir/cli"
    )
    
    func main() {
        // Grab the user inputed CLI flags
        cliFlags := cli.FlagsStruct{}
        cliErr := cli.StartCLI(&cliFlags, os.Args)
        if cliErr != nil {
            log.Println("Error grabbing command line args")
            log.Fatal(cliErr)
        }
    
        // Do stuff ...
    }
    

    /myDir/cli.go

    package cli
    
    import "github.com/urfave/cli"
    
    // FlagsStruct - holds command line args
    type FlagsStruct struct {
        MyFlag string
    }
    
    // StartCLI - gathers command line args
    func StartCLI(cliFlags *FlagsStruct, args []string) error {
        app := cli.NewApp()
        app.Action = func(ctx *cli.Context) error {
            MyFlag := ctx.GlobalString("my-flag")
    
            // build the cli struct to send back to main
            cliFlags.MyFlag = MyFlag
            return nil
        }
        app.Authors = []cli.Author{
            {
                Email: "my@email.com",
                Name:  "Adam Hanna",
            },
        }
        app.Flags = []cli.Flag{
            cli.StringFlag{
                Name:  "my-flag, f",
                Usage: "My flag usage goes here",
                Value: "myDefault",
            },
        }
        app.Name = "myAppName"
        app.Usage = "My App's Usage"
        app.Version = "0.0.1"
        return app.Run(args)
    }
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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