Tweak the testcontainers setup (#1460)

* Allow skipping port validation in tests.

* Add more test coverage.

* Fix linter.

* Fix DSN string generation.

* Add a `Migrator` test.

* Add a tmp folder.

* Make the linter happy.

* Add tests for `Streamer`.

* Close the `Streamer`.

* Fix linter issue.

* ignore contextcheck linter

---------

Co-authored-by: meiji163 <meiji163@github.com>

Author: arthurschreiber

Diff for: go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/stretchr/testify v1.9.0
 	github.com/testcontainers/testcontainers-go v0.34.0
 	golang.org/x/net v0.24.0
+	golang.org/x/sync v0.8.0
 	golang.org/x/term v0.19.0
 	golang.org/x/text v0.14.0
 )

Diff for: go.sum

@@ -199,6 +199,8 @@ golang.org/x/net v0.24.0/go.mod h1:2Q7sJY5mzlzWjKtYUEXSlBWCdyaioyXzRB2RtU8KVE8=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

Diff for: go/base/context.go

@@ -103,6 +103,11 @@ type MigrationContext struct {
 	AzureMySQL               bool
 	AttemptInstantDDL        bool
 
+	// SkipPortValidation allows skipping the port validation in `ValidateConnection`
+	// This is useful when connecting to a MySQL instance where the external port
+	// may not match the internal port.
+	SkipPortValidation bool
+
 	config            ContextConfig
 	configMutex       *sync.Mutex
 	ConfigFile        string

Diff for: go/base/utils.go

@@ -63,18 +63,27 @@ func StringContainsAll(s string, substrings ...string) bool {
 
 func ValidateConnection(db *gosql.DB, connectionConfig *mysql.ConnectionConfig, migrationContext *MigrationContext, name string) (string, error) {
 	versionQuery := `select @@global.version`
-	var port, extraPort int
+
 	var version string
 	if err := db.QueryRow(versionQuery).Scan(&version); err != nil {
 		return "", err
 	}
+
+	if migrationContext.SkipPortValidation {
+		return version, nil
+	}
+
+	var extraPort int
+
 	extraPortQuery := `select @@global.extra_port`
 	if err := db.QueryRow(extraPortQuery).Scan(&extraPort); err != nil { //nolint:staticcheck
 		// swallow this error. not all servers support extra_port
 	}
+
 	// AliyunRDS set users port to "NULL", replace it by gh-ost param
 	// GCP set users port to "NULL", replace it by gh-ost param
 	// Azure MySQL set users port to a different value by design, replace it by gh-ost para
+	var port int
 	if migrationContext.AliyunRDS || migrationContext.GoogleCloudPlatform || migrationContext.AzureMySQL {
 		port = connectionConfig.Key.Port
 	} else {