chore(prometheus): don't use global prometheus registry

And add tests.

prometheus/auth_service.go

@@ -38,19 +38,14 @@ func NewAuthorizationService() *AuthorizationService {
 		}, []string{"method", "error"}),
 	}
 
-	prometheus.MustRegister(
-		s.requestCount,
-		s.requestDuration,
-	)
-
 	return s
 }
 
 // FindAuthorizationByID returns an authorization given a id, records function call latency, and counts function calls.
 func (s *AuthorizationService) FindAuthorizationByID(ctx context.Context, id platform.ID) (a *platform.Authorization, err error) {
 	defer func(start time.Time) {
 		labels := prometheus.Labels{
-			"method": "FindAuthorizationsByID",
+			"method": "FindAuthorizationByID",
 			"error":  fmt.Sprint(err != nil),
 		}
 		s.requestCount.With(labels).Add(1)
@@ -63,7 +58,7 @@ func (s *AuthorizationService) FindAuthorizationByID(ctx context.Context, id pla
 func (s *AuthorizationService) FindAuthorizationByToken(ctx context.Context, t string) (a *platform.Authorization, err error) {
 	defer func(start time.Time) {
 		labels := prometheus.Labels{
-			"method": "FindAuthorizationsByToken",
+			"method": "FindAuthorizationByToken",
 			"error":  fmt.Sprint(err != nil),
 		}
 		s.requestCount.With(labels).Add(1)
@@ -113,3 +108,10 @@ func (s *AuthorizationService) DeleteAuthorization(ctx context.Context, id platf
 
 	return s.AuthorizationService.DeleteAuthorization(ctx, id)
 }
+
+func (s *AuthorizationService) PrometheusCollectors() []prometheus.Collector {
+	return []prometheus.Collector{
+		s.requestCount,
+		s.requestDuration,
+	}
+}

prometheus/auth_service_test.go

@@ -0,0 +1,144 @@
+package prometheus_test
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/influxdata/platform"
+	"github.com/influxdata/platform/kit/prom"
+	"github.com/influxdata/platform/kit/prom/promtest"
+	"github.com/influxdata/platform/prometheus"
+)
+
+// authzSvc is a test helper that returns its Err from every method on the AuthorizationService interface.
+type authzSvc struct {
+	Err error
+}
+
+var _ platform.AuthorizationService = (*authzSvc)(nil)
+
+func (a *authzSvc) FindAuthorizationByID(context.Context, platform.ID) (*platform.Authorization, error) {
+	return nil, a.Err
+}
+
+func (a *authzSvc) FindAuthorizationByToken(context.Context, string) (*platform.Authorization, error) {
+	return nil, a.Err
+}
+
+func (a *authzSvc) FindAuthorizations(context.Context, platform.AuthorizationFilter, ...platform.FindOptions) ([]*platform.Authorization, int, error) {
+	return nil, 0, a.Err
+}
+
+func (a *authzSvc) CreateAuthorization(context.Context, *platform.Authorization) error {
+	return a.Err
+}
+
+func (a *authzSvc) DeleteAuthorization(context.Context, platform.ID) error {
+	return a.Err
+}
+
+func TestAuthorizationService_Metrics(t *testing.T) {
+	a := new(authzSvc)
+
+	svc := prometheus.NewAuthorizationService()
+	svc.AuthorizationService = a
+	reg := prom.NewRegistry()
+	reg.MustRegister(svc.PrometheusCollectors()...)
+
+	ctx := context.Background()
+	id := platform.ID{1}
+
+	if _, err := svc.FindAuthorizationByID(ctx, id); err != nil {
+		t.Fatal(err)
+	}
+	mfs := promtest.MustGather(t, reg)
+	m := promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizationByID", "error": "false"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if _, err := svc.FindAuthorizationByToken(ctx, ""); err != nil {
+		t.Fatal(err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizationByToken", "error": "false"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if _, _, err := svc.FindAuthorizations(ctx, platform.AuthorizationFilter{}); err != nil {
+		t.Fatal(err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizations", "error": "false"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if err := svc.CreateAuthorization(ctx, nil); err != nil {
+		t.Fatal(err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "CreateAuthorization", "error": "false"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if err := svc.DeleteAuthorization(ctx, nil); err != nil {
+		t.Fatal(err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "DeleteAuthorization", "error": "false"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	forced := errors.New("forced error")
+	a.Err = forced
+
+	if _, err := svc.FindAuthorizationByID(ctx, id); err != forced {
+		t.Fatalf("expected forced error, got %v", err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizationByID", "error": "true"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if _, err := svc.FindAuthorizationByToken(ctx, ""); err != forced {
+		t.Fatalf("expected forced error, got %v", err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizationByToken", "error": "true"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if _, _, err := svc.FindAuthorizations(ctx, platform.AuthorizationFilter{}); err != forced {
+		t.Fatalf("expected forced error, got %v", err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "FindAuthorizations", "error": "true"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if err := svc.CreateAuthorization(ctx, nil); err != forced {
+		t.Fatalf("expected forced error, got %v", err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "CreateAuthorization", "error": "true"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+
+	if err := svc.DeleteAuthorization(ctx, nil); err != forced {
+		t.Fatalf("expected forced error, got %v", err)
+	}
+	mfs = promtest.MustGather(t, reg)
+	m = promtest.MustFindMetric(t, mfs, "auth_prometheus_requests_total", map[string]string{"method": "DeleteAuthorization", "error": "true"})
+	if got := m.GetCounter().GetValue(); got != 1 {
+		t.Fatalf("exp 1 request, got %v", got)
+	}
+}