I'm writing a small CLI application in Golang using urfave/cli framework and I'd like to write tests for it, but I can't find any useful information on how to test CLI applications, specifically written with the urfave/cli library. I have a lot of flags in the application and some of them are mutually exclusive and I'd like a proper test to stay on top of them - does anyone have an idea how to do it the right way?
EDIT: Consider the following minimal example of application with several flags and restrictions around them. How would you test these flags usage (requirements, exclusivity, etc.) and how they influence the functions when they're set or not?
package main
import (
"errors"
"fmt"
"os"
"github.com/urfave/cli"
)
func doSomething(flag1 string, flag2 string, flag3 bool, flag4 bool) error {
err := errors.New("something")
return err
}
func main() {
app := cli.NewApp()
app.Name = "greet"
app.Usage = "fight the loneliness!"
var flag1, flag2 string
var flag3, flag4 bool
app.Flags = []cli.Flag{
cli.StringFlag{
Name: "flag1",
Value: "",
Usage: "flag1",
Destination: &flag1,
},
cli.StringFlag{
Name: "flag2",
Value: "",
Usage: "flag2",
Destination: &flag2,
},
cli.BoolFlag{
Name: "flag3",
Usage: "flag3",
Destination: &flag3,
},
cli.BoolFlag{
Name: "flag4",
Usage: "flag4",
Destination: &flag4,
},
}
app.Action = func(c *cli.Context) error {
if flag1 != "" && c.NumFlags() > 1 {
fmt.Println("--flag1 flag cannot be used with any other flags")
cli.ShowAppHelp(c)
os.Exit(1)
}
if flag1 == "" && flag2 == "" || c.NumFlags() < 1 {
fmt.Println("--flag2 is required")
cli.ShowAppHelp(c)
os.Exit(1)
}
if flag3 && flag4 {
fmt.Println("--flag3 and --flag4 flags are mutually exclusive")
cli.ShowAppHelp(c)
os.Exit(1)
}
err := doSomething(flag1, flag2, flag3, flag4)
return err
}
}