internal/framework/flex: support set of enum expansion

internal/framework/flex/auto_expand.go

@@ -539,7 +539,13 @@ func (expander autoExpander) setOfString(ctx context.Context, vFrom basetypes.Se
 				return diags
 			}
 
-			vTo.Set(reflect.ValueOf(to))
+			// Copy elements individually to enable expansion of lists of
+			// custom string types (AWS enums)
+			vals := reflect.MakeSlice(vTo.Type(), len(to), len(to))
+			for i := 0; i < len(to); i++ {
+				vals.Index(i).SetString(to[i])
+			}
+			vTo.Set(vals)
 			return diags
 
 		case reflect.Ptr:

internal/framework/flex/auto_expand_test.go

@@ -731,6 +731,80 @@ func TestExpandStringEnum(t *testing.T) {
 	runAutoExpandTestCases(ctx, t, testCases)
 }
 
+func TestExpandListOfStringEnum(t *testing.T) {
+	t.Parallel()
+
+	type testEnum string
+	var testEnumFoo testEnum = "foo"
+	var testEnumBar testEnum = "bar"
+
+	var testEnums []testEnum
+	testEnumsWant := []testEnum{testEnumFoo, testEnumBar}
+
+	ctx := context.Background()
+	testCases := autoFlexTestCases{
+		{
+			TestName: "valid value",
+			Source: types.ListValueMust(types.StringType, []attr.Value{
+				types.StringValue(string(testEnumFoo)),
+				types.StringValue(string(testEnumBar)),
+			}),
+			Target:     &testEnums,
+			WantTarget: &testEnumsWant,
+		},
+		{
+			TestName:   "empty value",
+			Source:     types.ListValueMust(types.StringType, []attr.Value{}),
+			Target:     &testEnums,
+			WantTarget: &testEnums,
+		},
+		{
+			TestName:   "null value",
+			Source:     types.ListNull(types.StringType),
+			Target:     &testEnums,
+			WantTarget: &testEnums,
+		},
+	}
+	runAutoExpandTestCases(ctx, t, testCases)
+}
+
+func TestExpandSetOfStringEnum(t *testing.T) {
+	t.Parallel()
+
+	type testEnum string
+	var testEnumFoo testEnum = "foo"
+	var testEnumBar testEnum = "bar"
+
+	var testEnums []testEnum
+	testEnumsWant := []testEnum{testEnumFoo, testEnumBar}
+
+	ctx := context.Background()
+	testCases := autoFlexTestCases{
+		{
+			TestName: "valid value",
+			Source: types.SetValueMust(types.StringType, []attr.Value{
+				types.StringValue(string(testEnumFoo)),
+				types.StringValue(string(testEnumBar)),
+			}),
+			Target:     &testEnums,
+			WantTarget: &testEnumsWant,
+		},
+		{
+			TestName:   "empty value",
+			Source:     types.SetValueMust(types.StringType, []attr.Value{}),
+			Target:     &testEnums,
+			WantTarget: &testEnums,
+		},
+		{
+			TestName:   "null value",
+			Source:     types.SetNull(types.StringType),
+			Target:     &testEnums,
+			WantTarget: &testEnums,
+		},
+	}
+	runAutoExpandTestCases(ctx, t, testCases)
+}
+
 func TestExpandSimpleNestedBlockWithStringEnum(t *testing.T) {
 	t.Parallel()