Fixing the flaky test TestNodes (#3530)

Author: Lucas Wang

systest/group-delete/group_delete_test.go

@@ -34,7 +34,6 @@ import (
 	"github.com/dgraph-io/dgo/protos/api"
 	"github.com/dgraph-io/dgraph/z"
 	"github.com/stretchr/testify/require"
-	"google.golang.org/grpc"
 )
 
 func NodesSetup(t *testing.T, c *dgo.Dgraph) {
@@ -125,9 +124,8 @@ func getError(rc io.ReadCloser) error {
 }
 
 func TestNodes(t *testing.T) {
-	conn, err := grpc.Dial(z.SockAddr, grpc.WithInsecure())
-	require.NoError(t, err)
-	dg := dgo.NewDgraphClient(api.NewDgraphClient(conn))
+	dg, err := z.GetClientToGroup("1")
+	require.NoError(t, err, "error while getting connection to group 1")
 
 	NodesSetup(t, dg)
 

z/zero.go

@@ -22,13 +22,25 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/dgraph-io/dgo"
+	"github.com/dgraph-io/dgo/protos/api"
+	"google.golang.org/grpc"
 )
 
 // StateResponse represents the structure of the JSON object returned by calling
 // the /state endpoint in zero.
 type StateResponse struct {
 	Groups map[string]struct {
-		Members map[string]interface{} `json:"members"`
+		Members map[string]struct {
+			Addr       string `json:"addr"`
+			GroupID    int    `json:"groupId"`
+			ID         string `json:"id"`
+			LastUpdate string `json:"lastUpdate"`
+			Leader     bool   `json:"leader"`
+		} `json:"members"`
 		Tablets map[string]struct {
 			GroupID   int    `json:"groupId"`
 			Predicate string `json:"predicate"`
@@ -64,3 +76,39 @@ func GetState() (*StateResponse, error) {
 	}
 	return &st, nil
 }
+
+func GetClientToGroup(groupID string) (*dgo.Dgraph, error) {
+	state, err := GetState()
+	if err != nil {
+		return nil, err
+	}
+
+	group, ok := state.Groups[groupID]
+	if !ok {
+		return nil, fmt.Errorf("group %s does not exist", groupID)
+	}
+
+	if len(group.Members) == 0 {
+		return nil, fmt.Errorf("the group %s has no members", groupID)
+	}
+
+	member := group.Members["1"]
+	parts := strings.Split(member.Addr, ":")
+	if len(parts) != 2 {
+		return nil, fmt.Errorf("the member has an invalid address: %v", member.Addr)
+	}
+	// internalPort is used for communication between alpha nodes
+	internalPort, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse the port number from %s", parts[1])
+	}
+
+	// externalPort is for handling connections from clients
+	externalPort := internalPort + 2000
+
+	conn, err := grpc.Dial(fmt.Sprintf("localhost:%d", externalPort), grpc.WithInsecure())
+	if err != nil {
+		return nil, err
+	}
+	return dgo.NewDgraphClient(api.NewDgraphClient(conn)), nil
+}