return ServerError when failed to get cancelation confirmation

Author: Eygin Semen Leonidovich

mssql.go

@@ -243,8 +243,6 @@ func (c *Conn) checkBadConn(ctx context.Context, err error, mayRetry bool) error
 		return nil
 	case io.EOF:
 		c.connectionGood = false
-	case ErrorCancelConfirmation:
-		c.connectionGood = false
 	case driver.ErrBadConn:
 		// It is an internal programming error if driver.ErrBadConn
 		// is ever passed to this function. driver.ErrBadConn should

mssql_test.go

@@ -127,10 +127,6 @@ func TestCheckBadConn(t *testing.T) {
 		{io.EOF, true, false, newRetryableError(io.EOF), false},
 		{io.EOF, false, true, io.EOF, false},
 		{io.EOF, true, true, io.EOF, false},
-		{ErrorCancelConfirmation, false, false, ErrorCancelConfirmation, false},
-		{ErrorCancelConfirmation, true, false, newRetryableError(ErrorCancelConfirmation), false},
-		{ErrorCancelConfirmation, false, true, ErrorCancelConfirmation, false},
-		{ErrorCancelConfirmation, true, true, ErrorCancelConfirmation, false},
 		{netErr, false, false, netErr, false},
 		{netErr, true, false, newRetryableError(netErr), false},
 		{netErr, false, true, netErr, false},

queries_test.go

@@ -1419,8 +1419,8 @@ func TestProcessQueryCancelConfirmationError(t *testing.T) {
 		t.Error("processQueryResponse expected to fail but it succeeded")
 	}
 	// should not fail with ErrBadConn because query was successfully sent to server
-	if err != ErrorCancelConfirmation {
-		t.Error("processQueryResponse expected to fail with ErrorCancelConfirmation error but failed with other error: ", err)
+	if !errors.As(err, &ServerError{}) {
+		t.Error("processQueryResponse expected to fail with ServerError error but failed with other error: ", err)
 	}
 
 	if conn.connectionGood {

token.go

@@ -3,7 +3,6 @@ package mssql
 import (
 	"context"
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -99,8 +98,6 @@ const (
 	// TODO implement more flags
 )
 
-var ErrorCancelConfirmation = errors.New("did not get cancellation confirmation from the server")
-
 // interface for all tokens
 type tokenStruct interface{}
 
@@ -961,7 +958,7 @@ func (t tokenProcessor) nextToken() (tokenStruct, error) {
 		}
 		// we did not get cancellation confirmation, something is not
 		// right, this connection is not usable anymore
-		return nil, ErrorCancelConfirmation
+		return nil, ServerError{Error{Message: "did not get cancellation confirmation from the server"}}
 	}
 }