MM-23596: Ability to list private channels for team (#14925)

Summary:
store, app, api and go driver support for listing private channels

Ticket Link:
https://mattermost.atlassian.net/browse/MM-23596

app/app_iface.go

@@ -611,6 +611,7 @@ type AppIface interface {
 	GetPreferenceByCategoryForUser(userId string, category string) (model.Preferences, *model.AppError)
 	GetPreferencesForUser(userId string) (model.Preferences, *model.AppError)
 	GetPrevPostIdFromPostList(postList *model.PostList) string
+	GetPrivateChannelsForTeam(teamId string, offset int, limit int) (*model.ChannelList, *model.AppError)
 	GetProfileImage(user *model.User) ([]byte, bool, *model.AppError)
 	GetPublicChannelsByIdsForTeam(teamId string, channelIds []string) (*model.ChannelList, *model.AppError)
 	GetPublicChannelsForTeam(teamId string, offset int, limit int) (*model.ChannelList, *model.AppError)

app/channel.go

@@ -1635,6 +1635,10 @@ func (a *App) GetPublicChannelsForTeam(teamId string, offset int, limit int) (*m
 	return a.Srv().Store.Channel().GetPublicChannelsForTeam(teamId, offset, limit)
 }
 
+func (a *App) GetPrivateChannelsForTeam(teamId string, offset int, limit int) (*model.ChannelList, *model.AppError) {
+	return a.Srv().Store.Channel().GetPrivateChannelsForTeam(teamId, offset, limit)
+}
+
 func (a *App) GetChannelMember(channelId string, userId string) (*model.ChannelMember, *model.AppError) {
 	return a.Srv().Store.Channel().GetMember(channelId, userId)
 }

app/channel_test.go

@@ -924,6 +924,39 @@ func TestGetPublicChannelsForTeam(t *testing.T) {
 	assert.ElementsMatch(t, expectedChannels, channels)
 }
 
+func TestGetPrivateChannelsForTeam(t *testing.T) {
+	th := Setup(t)
+	team := th.CreateTeam()
+	defer th.TearDown()
+
+	var expectedChannels []*model.Channel
+	for i := 0; i < 8; i++ {
+		channel := model.Channel{
+			DisplayName: fmt.Sprintf("Private %v", i),
+			Name:        fmt.Sprintf("private_%v", i),
+			Type:        model.CHANNEL_PRIVATE,
+			TeamId:      team.Id,
+		}
+		var rchannel *model.Channel
+		rchannel, err := th.App.CreateChannel(&channel, false)
+		require.Nil(t, err)
+		require.NotNil(t, rchannel)
+		defer th.App.PermanentDeleteChannel(rchannel)
+
+		// Store the user ids for comparison later
+		expectedChannels = append(expectedChannels, rchannel)
+	}
+
+	// Fetch private channels multipile times
+	channelList, err := th.App.GetPrivateChannelsForTeam(team.Id, 0, 5)
+	require.Nil(t, err)
+	channelList2, err := th.App.GetPrivateChannelsForTeam(team.Id, 5, 5)
+	require.Nil(t, err)
+
+	channels := append(*channelList, *channelList2...)
+	assert.ElementsMatch(t, expectedChannels, channels)
+}
+
 func TestUpdateChannelMemberRolesChangingGuest(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()

app/opentracing_layer.go

@@ -6987,6 +6987,28 @@ func (a *OpenTracingAppLayer) GetPrevPostIdFromPostList(postList *model.PostList
 	return resultVar0
 }
 
+func (a *OpenTracingAppLayer) GetPrivateChannelsForTeam(teamId string, offset int, limit int) (*model.ChannelList, *model.AppError) {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetPrivateChannelsForTeam")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0, resultVar1 := a.app.GetPrivateChannelsForTeam(teamId, offset, limit)
+
+	if resultVar1 != nil {
+		span.LogFields(spanlog.Error(resultVar1))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0, resultVar1
+}
+
 func (a *OpenTracingAppLayer) GetProfileImage(user *model.User) ([]byte, bool, *model.AppError) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetProfileImage")