Merge pull request #2477 from allenflux/fix/initialize-constructor-values

fix: initialize parsers in collection value constructors

Reviewed-by: Naveen Gogineni <dear.chap@gmail.com>
Reviewed-by: Eng Zer Jun <engzerjun@gmail.com>
Tested-by: Eng Zer Jun <engzerjun@gmail.com>

Author: Juneezee

flag_map_impl.go

@@ -40,8 +40,12 @@ func (i MapBase[T, C, VC]) Create(val map[string]T, p *map[string]T, c C) Value
 
 // NewMapBase makes a *MapBase with default values
 func NewMapBase[T any, C any, VC ValueCreator[T, C]](defaults map[string]T) *MapBase[T, C, VC] {
+	var t T
+	var c C
+	var vc VC
 	return &MapBase[T, C, VC]{
-		dict: &defaults,
+		dict:  &defaults,
+		value: vc.Create(t, new(T), c),
 	}
 }
 

flag_slice_base.go

@@ -30,8 +30,12 @@ func (i SliceBase[T, C, VC]) Create(val []T, p *[]T, c C) Value {
 
 // NewSliceBase makes a *SliceBase with default values
 func NewSliceBase[T any, C any, VC ValueCreator[T, C]](defaults ...T) *SliceBase[T, C, VC] {
+	var t T
+	var c C
+	var vc VC
 	return &SliceBase[T, C, VC]{
 		slice: &defaults,
+		value: vc.Create(t, new(T), c),
 	}
 }
 

flag_test.go

@@ -2580,6 +2580,27 @@ func TestStringMap_Serialized_Set(t *testing.T) {
 	require.Equal(t, m0.String(), m1.String(), "pre and post serialization do not match")
 }
 
+func TestSliceAndMapConstructorsSet(t *testing.T) {
+	tests := []struct {
+		name  string
+		value Value
+		input string
+		want  any
+	}{
+		{"string slice", NewStringSlice("old"), "a,b", []string{"a", "b"}},
+		{"int slice", NewIntSlice(1), "2,3", []int{2, 3}},
+		{"uint slice", NewUintSlice(1), "2,3", []uint{2, 3}},
+		{"float slice", NewFloatSlice(1), "2.5,3.5", []float64{2.5, 3.5}},
+		{"string map", NewStringMap(map[string]string{"old": "v"}), "k=v", map[string]string{"k": "v"}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.NoError(t, tt.value.Set(tt.input))
+			require.Equal(t, tt.want, tt.value.Get())
+		})
+	}
+}
+
 var timestampFlagTests = []struct {
 	name     string
 	aliases  []string