[MM-22622] Add Ephemeral response when using mentions without permissions (#13902)

* MM-22282 Add Ephemeral response when using mentions without permission and add new prop to disable mention highlights on client

* MM-22622 Make test name test actually what it does and fix comment style

* MM-22622 Check ephemeral post created when post create with mentions on API

* MM-22622 More tests for App>CreatePost

* MM-22622 Make DisableMentionHighlights more concise and rename ephemeral post

* MM-22622 Dont send ephemeral message for system message created by user

* Trigger build

app/post_test.go

@@ -680,6 +680,56 @@ func TestCreatePost(t *testing.T) {
 		require.Nil(t, err)
 		assert.Equal(t, "![image]("+proxiedImageURL+")", rpost.Message)
 	})
+
+	t.Run("Sets prop MENTION_HIGHLIGHT_DISABLED when it should", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+		th.AddUserToChannel(th.BasicUser, th.BasicChannel)
+
+		t.Run("Does not set prop when user has USE_CHANNEL_MENTIONS", func(t *testing.T) {
+			postWithNoMention := &model.Post{
+				ChannelId: th.BasicChannel.Id,
+				Message:   "This post does not have mentions",
+				UserId:    th.BasicUser.Id,
+			}
+			rpost, err := th.App.CreatePost(postWithNoMention, th.BasicChannel, false)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+
+			postWithMention := &model.Post{
+				ChannelId: th.BasicChannel.Id,
+				Message:   "This post has @here mention @all",
+				UserId:    th.BasicUser.Id,
+			}
+			rpost, err = th.App.CreatePost(postWithMention, th.BasicChannel, false)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+		})
+
+		t.Run("Sets prop when post has mentions and user does not have USE_CHANNEL_MENTIONS", func(t *testing.T) {
+			th.RemovePermissionFromRole(model.PERMISSION_USE_CHANNEL_MENTIONS.Id, model.CHANNEL_USER_ROLE_ID)
+
+			postWithNoMention := &model.Post{
+				ChannelId: th.BasicChannel.Id,
+				Message:   "This post does not have mentions",
+				UserId:    th.BasicUser.Id,
+			}
+			rpost, err := th.App.CreatePost(postWithNoMention, th.BasicChannel, false)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+
+			postWithMention := &model.Post{
+				ChannelId: th.BasicChannel.Id,
+				Message:   "This post has @here mention @all",
+				UserId:    th.BasicUser.Id,
+			}
+			rpost, err = th.App.CreatePost(postWithMention, th.BasicChannel, false)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props[model.POST_PROPS_MENTION_HIGHLIGHT_DISABLED], true)
+
+			th.AddPermissionToRole(model.PERMISSION_USE_CHANNEL_MENTIONS.Id, model.CHANNEL_USER_ROLE_ID)
+		})
+	})
 }
 
 func TestPatchPost(t *testing.T) {
@@ -716,6 +766,53 @@ func TestPatchPost(t *testing.T) {
 		require.Nil(t, err)
 		assert.Equal(t, "![image]("+proxiedImageURL+")", rpost.Message)
 	})
+
+	t.Run("Sets Prop MENTION_HIGHLIGHT_DISABLED when it should", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+
+		th.AddUserToChannel(th.BasicUser, th.BasicChannel)
+
+		post := &model.Post{
+			ChannelId: th.BasicChannel.Id,
+			Message:   "This post does not have mentions",
+			UserId:    th.BasicUser.Id,
+		}
+
+		rpost, err := th.App.CreatePost(post, th.BasicChannel, false)
+		require.Nil(t, err)
+
+		t.Run("Does not set prop when user has USE_CHANNEL_MENTIONS", func(t *testing.T) {
+			patchWithNoMention := &model.PostPatch{Message: model.NewString("This patch has no channel mention")}
+
+			rpost, err = th.App.PatchPost(rpost.Id, patchWithNoMention)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+
+			patchWithMention := &model.PostPatch{Message: model.NewString("This patch has a mention now @here")}
+
+			rpost, err = th.App.PatchPost(rpost.Id, patchWithMention)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+		})
+
+		t.Run("Sets prop when user does not have USE_CHANNEL_MENTIONS", func(t *testing.T) {
+			th.RemovePermissionFromRole(model.PERMISSION_USE_CHANNEL_MENTIONS.Id, model.CHANNEL_USER_ROLE_ID)
+
+			patchWithNoMention := &model.PostPatch{Message: model.NewString("This patch still does not have a mention")}
+			rpost, err = th.App.PatchPost(rpost.Id, patchWithNoMention)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props, model.StringInterface{})
+
+			patchWithMention := &model.PostPatch{Message: model.NewString("This patch has a mention now @here")}
+
+			rpost, err = th.App.PatchPost(rpost.Id, patchWithMention)
+			require.Nil(t, err)
+			assert.Equal(t, rpost.Props[model.POST_PROPS_MENTION_HIGHLIGHT_DISABLED], true)
+
+			th.AddPermissionToRole(model.PERMISSION_USE_CHANNEL_MENTIONS.Id, model.CHANNEL_USER_ROLE_ID)
+		})
+	})
 }
 
 func TestPatchPostInArchivedChannel(t *testing.T) {