diff --git a/cloud/bmaas/scruffy/bmdb_stats_test.go b/cloud/bmaas/scruffy/bmdb_stats_test.go
new file mode 100644
index 0000000..89d5b5e
--- /dev/null
+++ b/cloud/bmaas/scruffy/bmdb_stats_test.go
@@ -0,0 +1,169 @@
+package scruffy
+
+import (
+	"context"
+	"fmt"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+
+	"source.monogon.dev/cloud/bmaas/bmdb"
+	"source.monogon.dev/cloud/bmaas/bmdb/model"
+	"source.monogon.dev/cloud/lib/component"
+)
+
+func TestBMDBStats(t *testing.T) {
+	s := Server{
+		Config: Config{
+			BMDB: bmdb.BMDB{
+				Config: bmdb.Config{
+					Database: component.CockroachConfig{
+						InMemory: true,
+					},
+				},
+			},
+		},
+	}
+
+	registry := prometheus.NewRegistry()
+	runner := newBMDBStatsRunner(&s, registry)
+
+	ctx, ctxC := context.WithCancel(context.Background())
+	defer ctxC()
+
+	expect := func(wantValues map[string]int64) {
+		t.Helper()
+		res, err := registry.Gather()
+		if err != nil {
+			t.Fatalf("Gather: %v", err)
+		}
+		gotValues := make(map[string]bool)
+		for _, mf := range res {
+			if len(mf.Metric) != 1 {
+				for _, m := range mf.Metric {
+					var lvs []string
+					for _, lp := range m.Label {
+						lvs = append(lvs, fmt.Sprintf("%s=%s", *lp.Name, *lp.Value))
+					}
+					sort.Strings(lvs)
+					name := fmt.Sprintf("%s[%s]", *mf.Name, strings.Join(lvs, ","))
+					gotValues[name] = true
+					if _, ok := wantValues[name]; !ok {
+						t.Errorf("MetricFamily %s: unexpected", name)
+					}
+					if want, got := wantValues[name], int64(*m.Gauge.Value); want != got {
+						t.Errorf("MetricFamily %s: wanted %d, got %d", *mf.Name, want, got)
+					}
+				}
+			} else {
+				m := mf.Metric[0]
+				gotValues[*mf.Name] = true
+				if want, got := wantValues[*mf.Name], int64(*m.Gauge.Value); want != got {
+					t.Errorf("MetricFamily %s: wanted %d, got %d", *mf.Name, want, got)
+				}
+				if _, ok := wantValues[*mf.Name]; !ok {
+					t.Errorf("MetricFamily %s: unexpected", *mf.Name)
+				}
+			}
+		}
+		for mf, _ := range wantValues {
+			if !gotValues[mf] {
+				t.Errorf("MetricFamily %s: missing", mf)
+			}
+		}
+	}
+
+	expect(map[string]int64{
+		"bmdb_stats_machines":                                    0,
+		"bmdb_stats_machines_provided":                           0,
+		"bmdb_stats_machines_heartbeating":                       0,
+		"bmdb_stats_machines_pending_installation":               0,
+		"bmdb_stats_machines_installed":                          0,
+		"bmdb_stats_machines_pending_agent_start":                0,
+		"bmdb_stats_machines_pending_agent_recovery":             0,
+		"bmdb_stats_active_backoffs[process=ShepherdAccess]":     0,
+		"bmdb_stats_active_backoffs[process=ShepherdAgentStart]": 0,
+		"bmdb_stats_active_backoffs[process=ShepherdRecovery]":   0,
+		"bmdb_stats_active_work[process=ShepherdAccess]":         0,
+		"bmdb_stats_active_work[process=ShepherdAgentStart]":     0,
+		"bmdb_stats_active_work[process=ShepherdRecovery]":       0,
+	})
+
+	conn, err := s.Config.BMDB.Open(true)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	sess, err := conn.StartSession(ctx)
+	if err != nil {
+		t.Fatalf("StartSession: %v", err)
+	}
+
+	s.bmdb = conn
+	s.sessionC = make(chan *bmdb.Session)
+	go s.sessionWorker(ctx)
+	if err := runner.runOnce(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	expect(map[string]int64{
+		"bmdb_stats_machines":                                    0,
+		"bmdb_stats_machines_provided":                           0,
+		"bmdb_stats_machines_heartbeating":                       0,
+		"bmdb_stats_machines_pending_installation":               0,
+		"bmdb_stats_machines_installed":                          0,
+		"bmdb_stats_machines_pending_agent_start":                0,
+		"bmdb_stats_machines_pending_agent_recovery":             0,
+		"bmdb_stats_active_backoffs[process=ShepherdAccess]":     0,
+		"bmdb_stats_active_backoffs[process=ShepherdAgentStart]": 0,
+		"bmdb_stats_active_backoffs[process=ShepherdRecovery]":   0,
+		"bmdb_stats_active_work[process=ShepherdAccess]":         0,
+		"bmdb_stats_active_work[process=ShepherdAgentStart]":     0,
+		"bmdb_stats_active_work[process=ShepherdRecovery]":       0,
+	})
+
+	f := fill().
+		// Provided, needs installation.
+		machine().providedE("1").build().
+		// Three machines needing recovery.
+		machine().providedE("2").agentNeverHeartbeat().build().
+		machine().providedE("3").agentNeverHeartbeat().build().
+		machine().providedE("4").agentNeverHeartbeat().build().
+		// One machine correctly heartbeating.
+		machine().providedE("5").agentHealthy().build().
+		// Two machines heartbeating and pending installation.
+		machine().providedE("6").agentHealthy().installRequested(10).build().
+		machine().providedE("7").agentHealthy().installRequested(10).installReported(9).build().
+		// Machine which is pending installation _and_ recovery.
+		machine().providedE("8").agentNeverHeartbeat().installRequested(10).build().
+		// Machine which has been successfully installed.
+		machine().providedE("9").agentStoppedHeartbeating().installRequested(10).installReported(10).build()
+
+	err = sess.Transact(ctx, func(q *model.Queries) error {
+		return f(ctx, q)
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := runner.runOnce(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	expect(map[string]int64{
+		"bmdb_stats_machines":                                    9,
+		"bmdb_stats_machines_provided":                           9,
+		"bmdb_stats_machines_heartbeating":                       3,
+		"bmdb_stats_machines_pending_installation":               3,
+		"bmdb_stats_machines_installed":                          1,
+		"bmdb_stats_machines_pending_agent_start":                1,
+		"bmdb_stats_machines_pending_agent_recovery":             4,
+		"bmdb_stats_active_backoffs[process=ShepherdAccess]":     0,
+		"bmdb_stats_active_backoffs[process=ShepherdAgentStart]": 0,
+		"bmdb_stats_active_backoffs[process=ShepherdRecovery]":   0,
+		"bmdb_stats_active_work[process=ShepherdAccess]":         0,
+		"bmdb_stats_active_work[process=ShepherdAgentStart]":     0,
+		"bmdb_stats_active_work[process=ShepherdRecovery]":       0,
+	})
+}