MM-47228 - restrict guest invitation flow if subscription plan does n… (#21195)

* MM-47228 - restrict guest invitation flow if subscription plan does not support it

* fix i18n texts and add unit test

* test the scenario where guest invites are blocked by subscription

* cover the success scenarios for cloud free trial and paid subscription

* fix go vet

* use the cloud prefix for the sku

* fix unit tests

* check the licence value to determine if the guest accounts are enabled

* remove unnecessary changes for getting the subscription information

* restrict user demotion if guestAccounts is not available in license

Co-authored-by: Pablo Velez Vidal <pablo.velez@mattermost.com>

api4/team_test.go

@@ -3361,6 +3361,52 @@ func TestInviteGuestsToTeam(t *testing.T) {
 	})
 }
 
+func TestInviteGuest(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+	guest1 := th.GenerateTestEmail()
+	guest2 := th.GenerateTestEmail()
+
+	emailList := []string{guest1, guest2}
+	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.GuestAccountsSettings.Enable = true })
+	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.ServiceSettings.EnableEmailInvitations = true })
+
+	t.Run("Guest Account not available in license returns forbidden", func(t *testing.T) {
+		th.App.Srv().SetLicense(model.NewTestLicenseWithFalseDefaults("guest_accounts"))
+
+		guestsInvite := model.GuestsInvite{
+			Emails:   emailList,
+			Channels: []string{th.BasicChannel.Id},
+			Message:  "test message",
+		}
+		buf, err := json.Marshal(guestsInvite)
+		require.NoError(t, err)
+
+		res, err := th.SystemAdminClient.DoAPIPost("/teams/"+th.BasicTeam.Id+"/invite-guests/email", string(buf))
+
+		require.Equal(t, http.StatusForbidden, res.StatusCode)
+		require.True(t, strings.Contains(err.Error(), "Guest accounts are disabled"))
+		require.Error(t, err)
+	})
+
+	t.Run("Guest Account available in license returns OK", func(t *testing.T) {
+		th.App.Srv().SetLicense(model.NewTestLicense("guest_accounts"))
+
+		guestsInvite := model.GuestsInvite{
+			Emails:   emailList,
+			Channels: []string{th.BasicChannel.Id},
+			Message:  "test message",
+		}
+		buf, err := json.Marshal(guestsInvite)
+		require.NoError(t, err)
+
+		res, err := th.SystemAdminClient.DoAPIPost("/teams/"+th.BasicTeam.Id+"/invite-guests/email", string(buf))
+
+		require.Equal(t, http.StatusOK, res.StatusCode)
+		require.NoError(t, err)
+	})
+}
+
 func TestGetTeamInviteInfo(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()