make x.Parsed() return true after AddGoFlagSet(x) and pflag.Parse() (#162)

* make GoFlagSets.Parsed() true after pflag.Parse

some third part lib such as glog use go flag package, and its some
actions depends on if goflag.Parsed().

* add test case for goflag.CommandLine.Parsed()

* add comment to goflag.CommandLine.Parsed test case

3 files changed, 20 insertions, 0 deletions

diff --git a/flag.go b/flag.go
index f0acbb8..e4e0c94 100644
--- a/flag.go
+++ b/flag.go
@@ -101,6 +101,7 @@ package pflag
 import (
 	"bytes"
 	"errors"
+	goflag "flag"
 	"fmt"
 	"io"
 	"os"
@@ -162,6 +163,8 @@ type FlagSet struct {
 	output            io.Writer // nil means stderr; use out() accessor
 	interspersed      bool      // allow interspersed option/non-option args
 	normalizeNameFunc func(f *FlagSet, name string) NormalizedName
+
+	addedGoFlagSets []*goflag.FlagSet
 }
 
 // A Flag represents the state of a flag.
@@ -1098,6 +1101,11 @@ func (f *FlagSet) parseArgs(args []string, fn parseFunc) (err error) {
 // are defined and before flags are accessed by the program.
 // The return value will be ErrHelp if -help was set but not defined.
 func (f *FlagSet) Parse(arguments []string) error {
+	if f.addedGoFlagSets != nil {
+		for _, goFlagSet := range f.addedGoFlagSets {
+			goFlagSet.Parse(nil)
+		}
+	}
 	f.parsed = true
 
 	if len(arguments) < 0 {
diff --git a/golangflag.go b/golangflag.go
index c4f47eb..d3dd72b 100644
--- a/golangflag.go
+++ b/golangflag.go
@@ -98,4 +98,8 @@ func (f *FlagSet) AddGoFlagSet(newSet *goflag.FlagSet) {
 	newSet.VisitAll(func(goflag *goflag.Flag) {
 		f.AddGoFlag(goflag)
 	})
+	if f.addedGoFlagSets == nil {
+		f.addedGoFlagSets = make([]*goflag.FlagSet, 0)
+	}
+	f.addedGoFlagSets = append(f.addedGoFlagSets, newSet)
 }
diff --git a/golangflag_test.go b/golangflag_test.go
index 77e2d7d..5bd831b 100644
--- a/golangflag_test.go
+++ b/golangflag_test.go
@@ -36,4 +36,12 @@ func TestGoflags(t *testing.T) {
 	if getBool != true {
 		t.Fatalf("expected getBool=true but got getBool=%v", getBool)
 	}
+	if !f.Parsed() {
+		t.Fatal("f.Parsed() return false after f.Parse() called")
+	}
+
+	// in fact it is useless. because `go test` called flag.Parse()
+	if !goflag.CommandLine.Parsed() {
+		t.Fatal("goflag.CommandLine.Parsed() return false after f.Parse() called")
+	}
 }