coredns/plugin/metrics/metrics_test.go

package metrics

import (
	"context"
	"testing"

	"github.com/coredns/coredns/plugin"
	"github.com/coredns/coredns/plugin/pkg/dnstest"
	"github.com/coredns/coredns/plugin/test"

	"github.com/miekg/dns"
)

func TestMetrics(t *testing.T) {
	met := New("localhost:0")
	if err := met.OnStartup(); err != nil {
		t.Fatalf("Failed to start metrics handler: %s", err)
	}
	defer met.OnFinalShutdown()

	met.AddZone("example.org.")

	tests := []struct {
		next          plugin.Handler
		qname         string
		qtype         uint16
		metric        string
		expectedValue string
	}{
		// This all works because 1 bucket (1 zone, 1 type)
		{
			next:          test.NextHandler(dns.RcodeSuccess, nil),
			qname:         "example.org.",
			metric:        "coredns_dns_requests_total",
			expectedValue: "1",
		},
		{
			next:          test.NextHandler(dns.RcodeSuccess, nil),
			qname:         "example.org.",
			metric:        "coredns_dns_requests_total",
			expectedValue: "2",
		},
		{
			next:          test.NextHandler(dns.RcodeSuccess, nil),
			qname:         "example.org.",
			metric:        "coredns_dns_requests_total",
			expectedValue: "3",
		},
		{
			next:          test.NextHandler(dns.RcodeSuccess, nil),
			qname:         "example.org.",
			metric:        "coredns_dns_responses_total",
			expectedValue: "4",
		},
	}

	ctx := context.TODO()

	for i, tc := range tests {
		req := new(dns.Msg)
		if tc.qtype == 0 {
			tc.qtype = dns.TypeA
		}
		req.SetQuestion(tc.qname, tc.qtype)
		met.Next = tc.next

		rec := dnstest.NewRecorder(&test.ResponseWriter{})
		_, err := met.ServeDNS(ctx, rec, req)
		if err != nil {
			t.Fatalf("Test %d: Expected no error, but got %s", i, err)
		}

		result := test.Scrape("http://" + ListenAddr + "/metrics")

		if tc.expectedValue != "" {
			got, _ := test.MetricValue(tc.metric, result)
			if got != tc.expectedValue {
				t.Errorf("Test %d: Expected value %s for metrics %s, but got %s", i, tc.expectedValue, tc.metric, got)
			}
		}
	}
}