use const instead of recording and alerting string in api_test.go

Author: sarthaktyagi-505

api/prometheus/v1/api_test.go

@@ -771,14 +771,14 @@ func TestAPIs(t *testing.T) {
 								Name:      "HighRequestLatency",
 								Query:     "job:request_latency_seconds:mean5m{job=\"myjob\"} > 0.5",
 								LastError: "",
-								Type:      "alerting",
+								Type:      string(RuleTypeAlerting),
 							},
 							RecordingRule{
 								Health:    RuleHealthGood,
 								Name:      "job:http_inprogress_requests:sum",
 								Query:     "sum(http_inprogress_requests) by (job)",
 								LastError: "",
-								Type:      "recording",
+								Type:      string(RuleTypeRecording),
 							},
 						},
 					},
@@ -872,7 +872,7 @@ func TestAPIs(t *testing.T) {
 								},
 								Name:           "HighRequestLatency",
 								Query:          "job:request_latency_seconds:mean5m{job=\"myjob\"} > 0.5",
-								Type:           "alerting",
+								Type:           string(RuleTypeAlerting),
 								EvaluationTime: 0.5,
 								LastEvaluation: time.Date(2020, 5, 18, 15, 52, 53, 450311300, time.UTC),
 								State:          "firing",
@@ -881,7 +881,7 @@ func TestAPIs(t *testing.T) {
 								Health:         RuleHealthGood,
 								Name:           "job:http_inprogress_requests:sum",
 								Query:          "sum(http_inprogress_requests) by (job)",
-								Type:           "recording",
+								Type:           string(RuleTypeRecording),
 								EvaluationTime: 0.3,
 								LastEvaluation: time.Date(2020, 5, 18, 15, 52, 53, 450311300, time.UTC),
 							},