MM-31713 Server/API: GetUserThread method (#16659)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/user_test.go

@@ -5668,6 +5668,45 @@ func TestThreadCounts(t *testing.T) {
 	})
 }
 
+func TestSingleThreadGet(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+	os.Setenv("MM_FEATUREFLAGS_COLLAPSEDTHREADS", "true")
+	defer os.Unsetenv("MM_FEATUREFLAGS_COLLAPSEDTHREADS")
+	th.App.UpdateConfig(func(cfg *model.Config) {
+		*cfg.ServiceSettings.ThreadAutoFollow = true
+		*cfg.ServiceSettings.CollapsedThreads = model.COLLAPSED_THREADS_DEFAULT_ON
+	})
+
+	Client := th.Client
+	defer th.App.Srv().Store.Post().PermanentDeleteByUser(th.BasicUser.Id)
+	defer th.App.Srv().Store.Post().PermanentDeleteByUser(th.SystemAdminUser.Id)
+
+	// create a post by regular user
+	rpost, _ := postAndCheck(t, Client, &model.Post{ChannelId: th.BasicChannel.Id, Message: "testMsg"})
+	// reply with another
+	time.Sleep(1)
+	postAndCheck(t, th.SystemAdminClient, &model.Post{ChannelId: th.BasicChannel.Id, Message: "testReply", RootId: rpost.Id})
+
+	// create another thread to check that we are not returning it by mistake
+	rpost2, _ := postAndCheck(t, Client, &model.Post{ChannelId: th.BasicChannel2.Id, Message: "testMsg2"})
+	time.Sleep(1)
+	postAndCheck(t, th.SystemAdminClient, &model.Post{ChannelId: th.BasicChannel2.Id, Message: "testReply", RootId: rpost2.Id})
+
+	// regular user should have two threads with 3 replies total
+	threads, _ := checkThreadListReplies(t, th, th.Client, th.BasicUser.Id, 2, 2, nil)
+
+	tr, resp := th.Client.GetUserThread(th.BasicUser.Id, th.BasicTeam.Id, threads.Threads[0].PostId, false)
+	CheckNoError(t, resp)
+	require.NotNil(t, tr)
+	require.Equal(t, threads.Threads[0].PostId, tr.PostId)
+	require.Empty(t, tr.Participants[0].Username)
+
+	tr, resp = th.Client.GetUserThread(th.BasicUser.Id, th.BasicTeam.Id, threads.Threads[0].PostId, true)
+	CheckNoError(t, resp)
+	require.NotEmpty(t, tr.Participants[0].Username)
+}
+
 func TestMaintainUnreadMentionsInThread(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()