Bug fix on JSON Tag (#6339)

Signed-off-by: Anand Rajagopal <[email protected]>

Author: rajagopalanand

Diff for: pkg/ruler/api.go

@@ -51,7 +51,7 @@ type Alert struct {
 // RuleDiscovery has info for all rules
 type RuleDiscovery struct {
 	RuleGroups     []*RuleGroup `json:"groups"`
-	GroupNextToken string       `json:"groupNextToken:omitempty"`
+	GroupNextToken string       `json:"groupNextToken,omitempty"`
 }
 
 // RuleGroup has info for rules which are part of a group

Diff for: pkg/ruler/api_test.go

@@ -4,11 +4,13 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/go-kit/log"
 	"github.com/gorilla/mux"
@@ -20,6 +22,90 @@ import (
 	"github.com/cortexproject/cortex/pkg/util/services"
 )
 
+func TestAPIResponseSerialization(t *testing.T) {
+	lastEvalTime := time.Now()
+	responseTime := lastEvalTime.Format(time.RFC3339Nano)
+	testCases := map[string]struct {
+		rules        RuleDiscovery
+		expectedJSON string
+	}{
+		"No rules": {
+			rules: RuleDiscovery{
+				RuleGroups: make([]*RuleGroup, 0),
+			},
+			expectedJSON: `{
+				"groups":[]
+			}`,
+		},
+		"Rules with no next token": {
+			rules: RuleDiscovery{
+				RuleGroups: []*RuleGroup{
+					{
+						Name:           "Test",
+						File:           "/rules/Test",
+						Rules:          make([]rule, 0),
+						Interval:       60,
+						LastEvaluation: lastEvalTime,
+						EvaluationTime: 10,
+						Limit:          0,
+					},
+				},
+			},
+			expectedJSON: fmt.Sprintf(`{
+				"groups": [
+					{
+						"evaluationTime": 10,
+						"limit": 0,
+						"name": "Test",
+						"file": "/rules/Test",
+						"interval": 60,
+						"rules": [],
+						"lastEvaluation": "%s"
+					}
+				]
+			}`, responseTime),
+		},
+		"Rules with next token": {
+			rules: RuleDiscovery{
+				RuleGroups: []*RuleGroup{
+					{
+						Name:           "Test",
+						File:           "/rules/Test",
+						Rules:          make([]rule, 0),
+						Interval:       60,
+						LastEvaluation: lastEvalTime,
+						EvaluationTime: 10,
+						Limit:          0,
+					},
+				},
+				GroupNextToken: "abcdef",
+			},
+			expectedJSON: fmt.Sprintf(`{
+				"groups": [
+					{
+						"evaluationTime": 10,
+						"limit": 0,
+						"name": "Test",
+						"file": "/rules/Test",
+						"interval": 60,
+						"rules": [],
+						"lastEvaluation": "%s"
+					}
+				],
+				"groupNextToken": "abcdef"
+			}`, responseTime),
+		},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			data, err := json.Marshal(&tc.rules)
+			require.NoError(t, err)
+			require.JSONEq(t, tc.expectedJSON, string(data))
+		})
+	}
+}
+
 func TestRuler_rules(t *testing.T) {
 	store := newMockRuleStore(mockRules, nil)
 	cfg := defaultRulerConfig(t)