Fix instance account not being created (#310)

* Rework 'CreateInstanceAccount' with better checking logic

* add test for create instance account

internal/db/bundb/admin.go

@@ -178,18 +178,19 @@ func (a *adminDB) NewSignup(ctx context.Context, username string, reason string,
 func (a *adminDB) CreateInstanceAccount(ctx context.Context) db.Error {
 	username := a.config.Host
 
-	// check if instance account already exists
-	existsQ := a.conn.
+	q := a.conn.
 		NewSelect().
 		Model(&gtsmodel.Account{}).
 		Where("username = ?", username).
 		WhereGroup(" AND ", whereEmptyOrNull("domain"))
-	count, err := existsQ.Count(ctx)
-	if err != nil && count == 1 {
+
+	exists, err := a.conn.Exists(ctx, q)
+	if err != nil {
+		return err
+	}
+	if exists {
 		logrus.Infof("instance account %s already exists", username)
 		return nil
-	} else if err != sql.ErrNoRows {
-		return a.conn.ProcessError(err)
 	}
 
 	key, err := rsa.GenerateKey(rand.Reader, 2048)

internal/db/bundb/admin_test.go

@@ -0,0 +1,56 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package bundb_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/testrig"
+)
+
+type AdminTestSuite struct {
+	BunDBStandardTestSuite
+}
+
+func (suite *AdminTestSuite) TestCreateInstanceAccount() {
+	// we need to take an empty db for this...
+	testrig.StandardDBTeardown(suite.db)
+	// ...with tables created but no data
+	testrig.CreateTestTables(suite.db)
+
+	// make sure there's no instance account in the db yet
+	acct, err := suite.db.GetInstanceAccount(context.Background(), suite.config.Host)
+	suite.Error(err)
+	suite.Nil(acct)
+
+	// create it
+	err = suite.db.CreateInstanceAccount(context.Background())
+	suite.NoError(err)
+
+	// and now check it exists
+	acct, err = suite.db.GetInstanceAccount(context.Background(), suite.config.Host)
+	suite.NoError(err)
+	suite.NotNil(acct)
+}
+
+func TestAdminTestSuite(t *testing.T) {
+	suite.Run(t, new(AdminTestSuite))
+}