fix: address review feedback and update doc

Author: somebadcode

flag_text.go

@@ -5,16 +5,16 @@ import (
 	"strings"
 )
 
-type TextMarshalUnmarshaller interface {
+type TextMarshalUnmarshaler interface {
 	encoding.TextMarshaler
 	encoding.TextUnmarshaler
 }
 
-// TextFlag enables you to set types that satisfies [TextMarshalUnmarshaller] using flags such as log levels.
-type TextFlag = FlagBase[TextMarshalUnmarshaller, StringConfig, TextValue]
+// TextFlag enables you to set types that satisfies [TextMarshalUnmarshaler] using flags such as log levels.
+type TextFlag = FlagBase[TextMarshalUnmarshaler, StringConfig, TextValue]
 
 type TextValue struct {
-	Value  *TextMarshalUnmarshaller
+	Value  *TextMarshalUnmarshaler
 	Config StringConfig
 }
 
@@ -39,9 +39,11 @@ func (f TextValue) Get() any {
 	return *f.Value
 }
 
-func (f TextValue) Create(v TextMarshalUnmarshaller, p *TextMarshalUnmarshaller, c StringConfig) Value {
+func (f TextValue) Create(v TextMarshalUnmarshaler, p *TextMarshalUnmarshaler, c StringConfig) Value {
 	if v != nil {
-		*p = v
+		b, _ := v.MarshalText()
+
+		_ = (*p).UnmarshalText(b)
 	}
 
 	return &TextValue{
@@ -50,7 +52,7 @@ func (f TextValue) Create(v TextMarshalUnmarshaller, p *TextMarshalUnmarshaller,
 	}
 }
 
-func (f TextValue) ToString(v TextMarshalUnmarshaller) string {
+func (f TextValue) ToString(v TextMarshalUnmarshaler) string {
 	text, err := v.MarshalText()
 	if err != nil {
 		return ""

flag_text_test.go

@@ -38,16 +38,18 @@ func TestTextFlag(t *testing.T) {
 			name: "empty",
 			flag: TextFlag{
 				Name:        "log-level",
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 			},
 			want: "INFO",
 		},
 		{
 			name: "info",
 			flag: TextFlag{
 				Name:        "log-level",
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
-				Validator: func(v TextMarshalUnmarshaller) error {
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+				Validator: func(v TextMarshalUnmarshaler) error {
 					text, err := v.MarshalText()
 					if err != nil {
 						return err
@@ -67,7 +69,8 @@ func TestTextFlag(t *testing.T) {
 			name: "debug",
 			flag: TextFlag{
 				Name:        "log-level",
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 			},
 			args: []string{"--log-level", "debug"},
 			want: "DEBUG",
@@ -76,7 +79,8 @@ func TestTextFlag(t *testing.T) {
 			name: "debug_with_trim",
 			flag: TextFlag{
 				Name:        "log-level",
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 				Config:      StringConfig{TrimSpace: true},
 			},
 			args: []string{"--log-level", " debug   "},
@@ -86,7 +90,8 @@ func TestTextFlag(t *testing.T) {
 			name: "invalid",
 			flag: TextFlag{
 				Name:        "log-level",
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 			},
 			args:    []string{"--log-level", "invalid"},
 			want:    "INFO",
@@ -97,7 +102,7 @@ func TestTextFlag(t *testing.T) {
 			flag: TextFlag{
 				Name:        "text",
 				Value:       &badMarshaller{},
-				Destination: ptr[TextMarshalUnmarshaller](&badMarshaller{}),
+				Destination: ptr[TextMarshalUnmarshaler](&badMarshaller{}),
 			},
 			args:    []string{"--text", "foo"},
 			wantErr: true,
@@ -113,7 +118,7 @@ func TestTextFlag(t *testing.T) {
 
 					return &l
 				}(),
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 			},
 			args: []string{},
 			want: "WARN",
@@ -129,7 +134,7 @@ func TestTextFlag(t *testing.T) {
 
 					return &l
 				}(),
-				Destination: ptr[TextMarshalUnmarshaller](&slog.LevelVar{}),
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
 			},
 			args: []string{"--log-level", "error"},
 			want: "ERROR",
@@ -141,6 +146,9 @@ func TestTextFlag(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			set := flag.NewFlagSet(tt.name, flag.ContinueOnError)
+
+			// If the test is expected to result in an error then the test needs to make sure that the test output is
+			// not littered with output that's expected but not relevant.
 			if tt.wantErr {
 				set.SetOutput(io.Discard)
 			}
@@ -149,12 +157,13 @@ func TestTextFlag(t *testing.T) {
 
 			err := set.Parse(tt.args)
 
-			require.False(t, (err != nil) && !tt.wantErr, tt.name)
+			// Ensure that there's only an error if we wanted an error.
+			require.False(t, (err != nil) && !tt.wantErr)
 
-			if tt.flag.Value != nil {
-				assert.Equal(t, tt.want, tt.flag.GetDefaultText())
-			}
+			assert.Equal(t, tt.flag.GetDefaultText(), set.Lookup(tt.flag.Name).DefValue)
 
+			// If the test is expected to fail and the code reaches this point then the test is successful and the test
+			// must therefore conclude.
 			if tt.wantErr {
 				return
 			}

godoc-current.txt

@@ -977,8 +977,8 @@ type SuggestCommandFunc func(commands []*Command, provided string) string
 
 type SuggestFlagFunc func(flags []Flag, provided string, hideHelp bool) string
 
-type TextFlag = FlagBase[TextMarshalUnMarshaller, StringConfig, TextValue]
-    TextFlag enables you to set types that satisfies TextMarshalUnMarshaller
+type TextFlag = FlagBase[TextMarshalUnmarshaler, StringConfig, TextValue]
+    TextFlag enables you to set types that satisfies TextMarshalUnmarshaler
     using flags such as log levels.
 
 type TextMarshalUnMarshaller interface {
@@ -987,19 +987,19 @@ type TextMarshalUnMarshaller interface {
 }
 
 type TextValue struct {
-	Value  TextMarshalUnMarshaller
+	Value  *TextMarshalUnmarshaler
 	Config StringConfig
 }
 
-func (v TextValue) Create(t TextMarshalUnMarshaller, _ *TextMarshalUnMarshaller, c StringConfig) Value
+func (v TextValue) Create(t TextMarshalUnmarshaler, p *TextMarshalUnmarshaler, c StringConfig) Value
 
 func (v TextValue) Get() any
 
 func (v TextValue) Set(s string) error
 
 func (v TextValue) String() string
 
-func (v TextValue) ToString(t TextMarshalUnMarshaller) string
+func (v TextValue) ToString(t TextMarshalUnmarshaler) string
 
 type TimestampArg = ArgumentBase[time.Time, TimestampConfig, timestampValue]