fix: Don't use meaningless slice pointers and reflect package

usergroups.go

@@ -3,7 +3,6 @@ package slack
 import (
 	"context"
 	"net/url"
-	"reflect"
 	"strings"
 )
 
@@ -208,10 +207,10 @@ func UpdateUserGroupsOptionDescription(description *string) UpdateUserGroupsOpti
 	}
 }
 
-// UpdateUserGroupsOptionChannels change the default channels of the User Group. (default: nil, so it's no-op)
-func UpdateUserGroupsOptionChannels(channels *[]string) UpdateUserGroupsOption {
+// UpdateUserGroupsOptionChannels change the default channels of the User Group. (default: unspecified, so it's no-op)
+func UpdateUserGroupsOptionChannels(channels []string) UpdateUserGroupsOption {
 	return func(params *UpdateUserGroupsParams) {
-		params.Channels = channels
+		params.Channels = &channels
 	}
 }
 
@@ -249,11 +248,11 @@ func (api *Client) UpdateUserGroupContext(ctx context.Context, userGroupID strin
 		values["handle"] = []string{params.Handle}
 	}
 
-	if !reflect.ValueOf(params.Description).IsNil() {
+	if params.Description != nil {
 		values["description"] = []string{*params.Description}
 	}
 
-	if !reflect.ValueOf(params.Channels).IsNil() {
+	if params.Channels != nil {
 		values["channels"] = []string{strings.Join(*params.Channels, ",")}
 	}
 

usergroups_test.go

@@ -222,9 +222,6 @@ func TestUpdateUserGroup(t *testing.T) {
 	emptyDescription := ""
 	presenceDescription := "Marketing gurus, PR experts and product advocates."
 
-	emptyChannels := []string{}
-	presenceChannels := []string{"channel1", "channel2"}
-
 	tests := []struct {
 		options    []UpdateUserGroupsOption
 		wantParams map[string]string
@@ -244,7 +241,7 @@ func TestUpdateUserGroup(t *testing.T) {
 		{
 			[]UpdateUserGroupsOption{
 				UpdateUserGroupsOptionDescription(&presenceDescription),
-				UpdateUserGroupsOptionChannels(&presenceChannels),
+				UpdateUserGroupsOptionChannels([]string{"channel1", "channel2"}),
 			},
 			map[string]string{
 				"token":       "testing-token",
@@ -256,7 +253,7 @@ func TestUpdateUserGroup(t *testing.T) {
 		{
 			[]UpdateUserGroupsOption{
 				UpdateUserGroupsOptionDescription(&emptyDescription),
-				UpdateUserGroupsOptionChannels(&emptyChannels),
+				UpdateUserGroupsOptionChannels([]string{}),
 			},
 			map[string]string{
 				"token":       "testing-token",