fix(requestflag): inspect underlying type in PostParse for empty string and bool env var handling

Author: Adityakk9031

internal/requestflag/requestflag.go

@@ -305,14 +305,16 @@ func (f *Flag[T]) PreParse() error {
 func (f *Flag[T]) PostParse() error {
 	if !f.hasBeenSet {
 		if val, source, found := f.Sources.LookupWithSource(); found {
-			if val != "" || reflect.TypeOf(f.value).Kind() == reflect.String {
+			tKind := reflect.TypeFor[T]().Kind()
+			isString := tKind == reflect.String || (tKind == reflect.Pointer && reflect.TypeFor[T]().Elem().Kind() == reflect.String)
+			if val != "" || isString {
 				if err := f.Set(f.Name, val); err != nil {
 					return fmt.Errorf(
 						"could not parse %[1]q as %[2]T value from %[3]s for flag %[4]s: %[5]s",
 						val, f.value, source, f.Name, err,
 					)
 				}
-			} else if val == "" && reflect.TypeOf(f.value).Kind() == reflect.Bool {
+			} else if val == "" && f.IsBoolFlag() {
 				_ = f.Set(f.Name, "false")
 			}
 

internal/requestflag/requestflag_test.go

@@ -1225,3 +1225,29 @@ func TestApplyStdinDataToFlags(t *testing.T) {
 		assert.False(t, flag.IsSet())
 	})
 }
+
+func TestFlagPostParse_EnvVars(t *testing.T) {
+	t.Run("string flag with empty env var", func(t *testing.T) {
+		t.Setenv("TEST_EMPTY_STR", "")
+		flag := &Flag[string]{
+			Name:    "str-flag",
+			Sources: cli.EnvVars("TEST_EMPTY_STR"),
+		}
+		assert.NoError(t, flag.PreParse())
+		assert.NoError(t, flag.PostParse())
+		assert.True(t, flag.IsSet())
+		assert.Equal(t, "", flag.Get())
+	})
+
+	t.Run("bool flag with empty env var", func(t *testing.T) {
+		t.Setenv("TEST_EMPTY_BOOL", "")
+		flag := &Flag[bool]{
+			Name:    "bool-flag",
+			Sources: cli.EnvVars("TEST_EMPTY_BOOL"),
+		}
+		assert.NoError(t, flag.PreParse())
+		assert.NoError(t, flag.PostParse())
+		assert.True(t, flag.IsSet())
+		assert.Equal(t, false, flag.Get())
+	})
+}