[GH-22254] check if bot user exists (#26545)

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/bot.go

@@ -33,15 +33,17 @@ func (a *App) EnsureBot(rctx request.CTX, pluginID string, bot *model.Bot) (stri
 		return "", errors.New("passed a bot with no username")
 	}
 
-	botIDBytes, err := a.GetPluginKey(pluginID, botUserKey)
+	botIDBytes, appErr := a.GetPluginKey(pluginID, botUserKey)
-	if err != nil {
+	if appErr != nil {
-		return "", err
+		return "", appErr
 	}
 
-	// If the bot has already been created, use it
+	// If the bot has already been created, check whether it still exists and use it
 	if botIDBytes != nil {
 		botID := string(botIDBytes)
-
+		if _, appErr = a.GetBot(rctx, botID, true); appErr != nil {
+			rctx.Logger().Debug("Unable to get bot.", mlog.String("bot_id", botID), mlog.Err(appErr))
+		} else {
 			// ensure existing bot is synced with what is being created
 			botPatch := &model.BotPatch{
 				Username:    &bot.Username,
@@ -49,18 +51,19 @@ func (a *App) EnsureBot(rctx request.CTX, pluginID string, bot *model.Bot) (stri
 				Description: &bot.Description,
 			}
 
-		if _, err = a.PatchBot(rctx, botID, botPatch); err != nil {
+			if _, appErr = a.PatchBot(rctx, botID, botPatch); appErr != nil {
-			return "", fmt.Errorf("failed to patch bot: %w", err)
+				return "", fmt.Errorf("failed to patch bot: %w", appErr)
 			}
 
 			return botID, nil
 		}
+	}
 
 	// Check for an existing bot user with that username. If one exists, then use that.
 	if user, appErr := a.GetUserByUsername(bot.Username); appErr == nil && user != nil {
 		if user.IsBot {
 			if appErr := a.SetPluginKey(pluginID, botUserKey, []byte(user.Id)); appErr != nil {
-				return "", fmt.Errorf("failed to set plugin key: %w", err)
+				return "", fmt.Errorf("failed to set plugin key: %w", appErr)
 			}
 		} else {
 			rctx.Logger().Error("Plugin attempted to use an account that already exists. Convert user to a bot "+
@@ -82,7 +85,7 @@ func (a *App) EnsureBot(rctx request.CTX, pluginID string, bot *model.Bot) (stri
 	}
 
 	if appErr := a.SetPluginKey(pluginID, botUserKey, []byte(createdBot.UserId)); appErr != nil {
-		return "", fmt.Errorf("failed to set plugin key: %w", err)
+		return "", fmt.Errorf("failed to set plugin key: %w", appErr)
 	}
 
 	return createdBot.UserId, nil

server/channels/app/bot_test.go

@@ -112,6 +112,80 @@ func TestCreateBot(t *testing.T) {
 	})
 }
 
+func TestEnsureBot(t *testing.T) {
+	t.Run("ensure bot should pass if already exist bot user", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+		pluginId := "pluginId"
+
+		appErr := th.App.SetPluginKey(pluginId, "key", []byte("test"))
+		require.Nil(t, appErr)
+
+		botID1, err := th.App.EnsureBot(th.Context, pluginId, &model.Bot{
+			Username:    "username",
+			Description: "a bot",
+			OwnerId:     th.BasicUser.Id,
+		})
+		require.NoError(t, err)
+
+		bot, appErr := th.App.GetBot(th.Context, botID1, true)
+		require.Nil(t, appErr)
+		assert.Equal(t, "username", bot.Username)
+		assert.Equal(t, "a bot", bot.Description)
+
+		botID2, err := th.App.EnsureBot(th.Context, pluginId, &model.Bot{
+			Username:    "another_username",
+			Description: "another bot",
+			OwnerId:     th.BasicUser.Id,
+		})
+		require.NoError(t, err)
+		assert.Equal(t, botID1, botID2)
+
+		bot, appErr = th.App.GetBot(th.Context, botID2, true)
+		require.Nil(t, appErr)
+		assert.Equal(t, "another_username", bot.Username)
+		assert.Equal(t, "another bot", bot.Description)
+	})
+
+	t.Run("ensure bot should pass even after delete bot user", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+		pluginId := "pluginId"
+
+		appErr := th.App.SetPluginKey(pluginId, "key", []byte("test"))
+		require.Nil(t, appErr)
+
+		initialBot := model.Bot{
+			Username:    "username",
+			Description: "a bot",
+			OwnerId:     th.BasicUser.Id,
+		}
+
+		botID1, err := th.App.EnsureBot(th.Context, pluginId, &initialBot)
+		require.NoError(t, err)
+
+		bot, appErr := th.App.GetBot(th.Context, botID1, true)
+		require.Nil(t, appErr)
+		assert.Equal(t, "username", bot.Username)
+		assert.Equal(t, "a bot", bot.Description)
+
+		err = th.App.Srv().Store().User().PermanentDelete(initialBot.UserId)
+		require.NoError(t, err)
+		botID2, err := th.App.EnsureBot(th.Context, pluginId, &model.Bot{
+			Username:    "another_username",
+			Description: "another bot",
+			OwnerId:     th.BasicUser.Id,
+		})
+		require.NoError(t, err)
+		assert.NotEqual(t, botID1, botID2)
+
+		bot, appErr = th.App.GetBot(th.Context, botID2, true)
+		require.Nil(t, appErr)
+		assert.Equal(t, "another_username", bot.Username)
+		assert.Equal(t, "another bot", bot.Description)
+	})
+}
+
 func TestPatchBot(t *testing.T) {
 	t.Run("invalid patch for user", func(t *testing.T) {
 		th := Setup(t).InitBasic()