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//go:build go1.21
// +build go1.21
package pflag
import (
"errors"
"flag"
"io"
"strings"
"testing"
)
func TestFuncCompat(t *testing.T) {
// compare behavior with the stdlib 'flag' package
type FuncFlagSet interface {
Func(name string, usage string, fn func(string) error)
Parse([]string) error
}
unitTestErr := errors.New("unit test error")
runCase := func(f FuncFlagSet, name string, args []string) (values []string, err error) {
fn := func(s string) error {
values = append(values, s)
if s == "err" {
return unitTestErr
}
return nil
}
f.Func(name, "Callback function", fn)
err = f.Parse(args)
return values, err
}
t.Run("regular parsing", func(t *testing.T) {
flagName := "fnflag"
args := []string{"--fnflag=xx", "--fnflag", "yy", "--fnflag=zz"}
stdFSet := flag.NewFlagSet("std test", flag.ContinueOnError)
stdValues, err := runCase(stdFSet, flagName, args)
if err != nil {
t.Fatalf("std flag: expected no error, got %v", err)
}
expected := []string{"xx", "yy", "zz"}
if !cmpLists(expected, stdValues) {
t.Fatalf("std flag: expected %v, got %v", expected, stdValues)
}
fset := NewFlagSet("pflag test", ContinueOnError)
pflagValues, err := runCase(fset, flagName, args)
if err != nil {
t.Fatalf("pflag: expected no error, got %v", err)
}
if !cmpLists(stdValues, pflagValues) {
t.Fatalf("pflag: expected %v, got %v", stdValues, pflagValues)
}
})
t.Run("error triggered by callback", func(t *testing.T) {
flagName := "fnflag"
args := []string{"--fnflag", "before", "--fnflag", "err", "--fnflag", "after"}
// test behavior of standard flag.Fset with an error triggered by the callback:
// (note: as can be seen in 'runCase()', if the callback sees "err" as a value
// for the flag, it will return an error)
stdFSet := flag.NewFlagSet("std test", flag.ContinueOnError)
stdFSet.SetOutput(io.Discard) // suppress output
// run test case with standard flag.Fset
stdValues, err := runCase(stdFSet, flagName, args)
// double check the standard behavior:
// - .Parse() should return an error, which contains the error message
if err == nil {
t.Fatalf("std flag: expected an error triggered by callback, got no error instead")
}
if !strings.HasSuffix(err.Error(), unitTestErr.Error()) {
t.Fatalf("std flag: expected unittest error, got unexpected error value: %T %v", err, err)
}
// - the function should have been called twice, with the first two values,
// the final "=after" should not be recorded
expected := []string{"before", "err"}
if !cmpLists(expected, stdValues) {
t.Fatalf("std flag: expected %v, got %v", expected, stdValues)
}
// now run the test case on a pflag FlagSet:
fset := NewFlagSet("pflag test", ContinueOnError)
pflagValues, err := runCase(fset, flagName, args)
// check that there is a similar error (note: pflag will _wrap_ the error, while the stdlib
// currently keeps the original message but creates a flat errors.Error)
if !errors.Is(err, unitTestErr) {
t.Fatalf("pflag: got unexpected error value: %T %v", err, err)
}
// the callback should be called the same number of times, with the same values:
if !cmpLists(stdValues, pflagValues) {
t.Fatalf("pflag: expected %v, got %v", stdValues, pflagValues)
}
})
}
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