test: add e2e test verifying the changes work as intended

Signed-off-by: Manan Gupta <manan@planetscale.com>

go/test/endtoend/transaction/twopc/twopc_test.go

@@ -19,8 +19,10 @@ package transaction
 import (
 	"context"
 	_ "embed"
+	"fmt"
 	"reflect"
 	"sort"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -849,6 +851,19 @@ func TestDTResolveAfterTransactionRecord(t *testing.T) {
 	_, err = conn.Execute(newCtx, "commit", nil)
 	require.ErrorContains(t, err, "Fail After TR created")
 
+	t.Run("ReadTransactionState", func(t *testing.T) {
+		errStr := err.Error()
+		indx := strings.Index(errStr, "Fail")
+		require.Greater(t, indx, 0)
+		dtid := errStr[0 : indx-2]
+		res, err := conn.Execute(context.Background(), fmt.Sprintf(`show transaction status for '%v'`, dtid), nil)
+		require.NoError(t, err)
+		resStr := fmt.Sprintf("%v", res.Rows)
+		require.Contains(t, resStr, `[[VARCHAR("ks:80-`)
+		require.Contains(t, resStr, `VARCHAR("PREPARE") DATETIME("`)
+		require.Contains(t, resStr, `+0000 UTC") VARCHAR("ks:-80")]]`)
+	})
+
 	// Below check ensures that the transaction is resolved by the resolver on receiving unresolved transaction signal from MM.
 	tableMap := make(map[string][]*querypb.Field)
 	dtMap := make(map[string]string)

go/vt/vtgate/tx_conn.go

@@ -22,6 +22,8 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/pkg/errors"
+
 	"vitess.io/vitess/go/mysql/sqlerror"
 	"vitess.io/vitess/go/vt/callerid"
 	"vitess.io/vitess/go/vt/concurrency"
@@ -204,7 +206,7 @@ func (txc *TxConn) commit2PC(ctx context.Context, session *SafeSession) error {
 	if DEBUG_2PC {
 		// Test code to simulate a failure after RM prepare
 		if failNow, err := checkTestFailure(callerid.EffectiveCallerIDFromContext(ctx), "TRCreated_FailNow", nil); failNow {
-			return err
+			return errors.Wrapf(err, "%v", dtid)
 		}
 	}