feat: add PFlagSetProvider interface to access underlying pflag.FlagS…

…et (#18)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

flag_set.go

@@ -20,13 +20,20 @@ type FlagSet interface {
 	StringArrayVarP(p *[]string, name, shorthand, usage string)
 }
 
+type PFlagSetProvider interface {
+	PFlagSet() *pflag.FlagSet
+}
+
 type pflagSet struct {
 	ignoreDuplicates bool
 	log              logger.Logger
 	flagSet          *pflag.FlagSet
 }
 
-var _ FlagSet = (*pflagSet)(nil)
+var _ interface {
+	FlagSet
+	PFlagSetProvider
+} = (*pflagSet)(nil)
 
 func NewPFlagSet(log logger.Logger, flags *pflag.FlagSet) FlagSet {
 	return &pflagSet{
@@ -36,6 +43,10 @@ func NewPFlagSet(log logger.Logger, flags *pflag.FlagSet) FlagSet {
 	}
 }
 
+func (f *pflagSet) PFlagSet() *pflag.FlagSet {
+	return f.flagSet
+}
+
 func (f *pflagSet) exists(name, shorthand string) bool {
 	if !f.ignoreDuplicates {
 		return false

flags_test.go

@@ -4,11 +4,19 @@ import (
 	"testing"
 
 	"github.com/spf13/pflag"
-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/anchore/go-logger/adapter/discard"
 )
 
+func Test_PFlagSetProvider(t *testing.T) {
+	flags := pflag.NewFlagSet("set", pflag.ContinueOnError)
+	flagSet := NewPFlagSet(discard.New(), flags)
+	prov, ok := flagSet.(PFlagSetProvider)
+	require.True(t, ok)
+	require.Equal(t, flags, prov.PFlagSet())
+}
+
 func Test_EmbeddedAddFlags(t *testing.T) {
 	type ty1 struct {
 		Something string
@@ -25,7 +33,7 @@ func Test_EmbeddedAddFlags(t *testing.T) {
 		flagNames = append(flagNames, flag.Name)
 	})
 
-	assert.Equal(t, flagNames, []string{"sub2-flag"})
+	require.Equal(t, flagNames, []string{"sub2-flag"})
 }
 
 func Test_AddFlags(t *testing.T) {
@@ -38,10 +46,10 @@ func Test_AddFlags(t *testing.T) {
 		flagNames = append(flagNames, flag.Name)
 	})
 
-	assert.Len(t, flagNames, 3)
-	assert.Contains(t, flagNames, "t1-flag")
-	assert.Contains(t, flagNames, "sub2-flag")
-	assert.Contains(t, flagNames, "sub3-flag")
+	require.Len(t, flagNames, 3)
+	require.Contains(t, flagNames, "t1-flag")
+	require.Contains(t, flagNames, "sub2-flag")
+	require.Contains(t, flagNames, "sub3-flag")
 }
 
 type Sub2 struct {