MM-63791: guest permissions to teams (#30789)

* improve th.CreateGuestAndClient

* test coverage for guest user access to teams

* restrict guest access to public teams unless a member

server/channels/api4/apitestlib.go

@@ -695,7 +695,8 @@ func (th *TestHelper) CreateUserWithAuth(authService string) *model.User {
 // CreateGuestAndClient creates a guest user, adds them to the basic
 // team, basic channel and basic private channel, and generates an API
 // client ready to use
-func (th *TestHelper) CreateGuestAndClient() (*model.User, *model.Client4) {
+func (th *TestHelper) CreateGuestAndClient(tb testing.TB) (*model.User, *model.Client4) {
+	tb.Helper()
 	id := model.NewId()
 
 	// create a guest user and add it to the basic team and public/private channels
@@ -706,23 +707,17 @@ func (th *TestHelper) CreateGuestAndClient() (*model.User, *model.Client4) {
 		Password:      "Password1",
 		EmailVerified: true,
 	})
-	if cgErr != nil {
-		panic(cgErr)
-	}
+	require.Nil(tb, cgErr)
 
-	_, _, tErr := th.App.AddUserToTeam(th.Context, th.BasicTeam.Id, guest.Id, th.SystemAdminUser.Id)
-	if tErr != nil {
-		panic(tErr)
-	}
+	_, _, appErr := th.App.AddUserToTeam(th.Context, th.BasicTeam.Id, guest.Id, th.SystemAdminUser.Id)
+	require.Nil(tb, appErr)
 	th.AddUserToChannel(guest, th.BasicChannel)
 	th.AddUserToChannel(guest, th.BasicPrivateChannel)
 
 	// create a client and login the guest
 	guestClient := th.CreateClient()
-	_, _, lErr := guestClient.Login(context.Background(), guest.Username, "Password1")
-	if lErr != nil {
-		panic(lErr)
-	}
+	_, _, err := guestClient.Login(context.Background(), guest.Email, "Password1")
+	require.NoError(tb, err)
 
 	return guest, guestClient
 }