MM-53703 Add display-name for experimental default channel (#26191)

* [MM-53703] add displayname for experimental default channel (#24644)

* [MM-53703] add unit test for default experimental channel (#24644)

* Update server/channels/app/teams/teams_test.go

---------

Co-authored-by: Sazzad Hossain <sazzad.hossain@marginedge.com>
Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Harrison Healey <harrisonmhealey@gmail.com>

server/channels/app/teams/teams_test.go

@@ -31,6 +31,47 @@ func TestCreateTeam(t *testing.T) {
 	require.Error(t, err, "Should not create a new team - team already exist")
 }
 
+func TestCreateTeamWithExperimentalDefaultChannels(t *testing.T) {
+	th := Setup(t)
+	th.UpdateConfig(func(cfg *model.Config) {
+		cfg.TeamSettings.ExperimentalDefaultChannels = []string{"channel-1", "channel-2"}
+	})
+	defer th.TearDown()
+
+	id := model.NewId()
+	team := &model.Team{
+		DisplayName: "dn_" + id,
+		Name:        "name" + id,
+		Email:       "success+" + id + "@simulator.amazonses.com",
+		Type:        model.TeamOpen,
+	}
+
+	_, err := th.service.CreateTeam(th.Context, team)
+	require.NoError(t, err, "Should create a new team")
+
+	createdTeam, err := th.service.GetTeam(team.Id)
+	require.NoError(t, err)
+	require.Equal(t, createdTeam.Name, "name"+id)
+
+	channels, err := th.service.channelStore.GetAll(team.Id)
+	require.NoError(t, err)
+	require.Len(t, channels, 3)
+
+	ch, err := th.service.channelStore.GetByName(team.Id, "town-square", false)
+	require.NoError(t, err)
+	require.NotNil(t, ch)
+
+	ch, err = th.service.channelStore.GetByName(team.Id, "channel-1", false)
+	require.NoError(t, err)
+	require.NotNil(t, ch)
+	require.Equal(t, ch.DisplayName, "channel-1")
+
+	ch, err = th.service.channelStore.GetByName(team.Id, "channel-2", false)
+	require.NoError(t, err)
+	require.NotNil(t, ch)
+	require.Equal(t, ch.DisplayName, "channel-2")
+}
+
 func TestJoinUserToTeam(t *testing.T) {
 	th := Setup(t)
 	defer th.TearDown()