Fix master/slave bug (#1601)

fix test

Fix master/slave bug

Reviewed-on: https://gitea.com/xorm/xorm/pulls/1601

engine.go

@@ -32,7 +32,6 @@ import (
 // Commonly, an application only need one engine
 type Engine struct {
 	cacherMgr      *caches.Manager
-	db             *core.DB
 	defaultContext context.Context
 	dialect        dialects.Dialect
 	engineGroup    *EngineGroup

engine_group.go

@@ -161,17 +161,17 @@ func (eg *EngineGroup) SetMapper(mapper names.Mapper) {
 
 // SetMaxIdleConns set the max idle connections on pool, default is 2
 func (eg *EngineGroup) SetMaxIdleConns(conns int) {
-	eg.Engine.db.SetMaxIdleConns(conns)
+	eg.Engine.dialect.DB().SetMaxIdleConns(conns)
 	for i := 0; i < len(eg.slaves); i++ {
-		eg.slaves[i].db.SetMaxIdleConns(conns)
+		eg.slaves[i].dialect.DB().SetMaxIdleConns(conns)
 	}
 }
 
 // SetMaxOpenConns is only available for go 1.2+
 func (eg *EngineGroup) SetMaxOpenConns(conns int) {
-	eg.Engine.db.SetMaxOpenConns(conns)
+	eg.Engine.dialect.DB().SetMaxOpenConns(conns)
 	for i := 0; i < len(eg.slaves); i++ {
-		eg.slaves[i].db.SetMaxOpenConns(conns)
+		eg.slaves[i].dialect.DB().SetMaxOpenConns(conns)
 	}
 }
 

engine_group_test.go

@@ -0,0 +1,33 @@
+// Copyright 2020 The Xorm Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package xorm
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"xorm.io/xorm/log"
+	"xorm.io/xorm/schemas"
+)
+
+func TestEngineGroup(t *testing.T) {
+	assert.NoError(t, prepareEngine())
+
+	master := testEngine.(*Engine)
+	if master.Dialect().URI().DBType == schemas.SQLITE {
+		t.Skip()
+		return
+	}
+
+	eg, err := NewEngineGroup(master, []*Engine{master})
+	assert.NoError(t, err)
+
+	eg.SetMaxIdleConns(10)
+	eg.SetMaxOpenConns(100)
+	eg.SetTableMapper(master.GetTableMapper())
+	eg.SetColumnMapper(master.GetColumnMapper())
+	eg.SetLogLevel(log.LOG_INFO)
+	eg.ShowSQL(true)
+}