Fix bug in URL builder for NodesInfo API

Close #1078

Author: olivere

nodes_info.go

@@ -30,8 +30,6 @@ type NodesInfoService struct {
 func NewNodesInfoService(client *Client) *NodesInfoService {
 	return &NodesInfoService{
 		client: client,
-		nodeId: []string{"_all"},
-		metric: []string{"_all"},
 	}
 }
 
@@ -71,10 +69,24 @@ func (s *NodesInfoService) Pretty(pretty bool) *NodesInfoService {
 
 // buildURL builds the URL for the operation.
 func (s *NodesInfoService) buildURL() (string, url.Values, error) {
+	var nodeId, metric string
+
+	if len(s.nodeId) > 0 {
+		nodeId = strings.Join(s.nodeId, ",")
+	} else {
+		nodeId = "_all"
+	}
+
+	if len(s.metric) > 0 {
+		metric = strings.Join(s.metric, ",")
+	} else {
+		metric = "_all"
+	}
+
 	// Build URL
 	path, err := uritemplates.Expand("/_nodes/{node_id}/{metric}", map[string]string{
-		"node_id": strings.Join(s.nodeId, ","),
-		"metric":  strings.Join(s.metric, ","),
+		"node_id": nodeId,
+		"metric":  metric,
 	})
 	if err != nil {
 		return "", url.Values{}, err

nodes_info_test.go

@@ -9,6 +9,51 @@ import (
 	"testing"
 )
 
+func TestNodesInfoBuildURL(t *testing.T) {
+	client := setupTestClientAndCreateIndex(t)
+
+	tests := []struct {
+		NodeIDs  []string
+		Metrics  []string
+		Expected string
+	}{
+		{
+			nil,
+			nil,
+			"/_nodes/_all/_all",
+		},
+		{
+			[]string{},
+			[]string{},
+			"/_nodes/_all/_all",
+		},
+		{
+			[]string{"node1"},
+			[]string{},
+			"/_nodes/node1/_all",
+		},
+		{
+			[]string{"node1", "node2"},
+			nil,
+			"/_nodes/node1%2Cnode2/_all",
+		},
+		{
+			[]string{"node1", "node2"},
+			[]string{"metric1", "metric2"},
+			"/_nodes/node1%2Cnode2/metric1%2Cmetric2",
+		},
+	}
+
+	for i, test := range tests {
+		path, _, err := client.NodesInfo().NodeId(test.NodeIDs...).Metric(test.Metrics...).buildURL()
+		if err != nil {
+			t.Fatalf("case #%d: %v", i+1, err)
+		}
+		if path != test.Expected {
+			t.Errorf("case #%d: expected %q; got: %q", i+1, test.Expected, path)
+		}
+	}
+}
 func TestNodesInfo(t *testing.T) {
 	client, err := NewClient()
 	if err != nil {