feat(multiplayer): expose allocator quota metrics

server/allocator/metrics_test.go

@@ -0,0 +1,60 @@
+package allocator
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestMetricsExportsFixedRegionalCounters(t *testing.T) {
+	metrics := NewMetrics()
+	metrics.ObserveAttempt("EU")
+	metrics.ObserveSuccess("EU")
+	metrics.ObserveFailure("EU")
+	metrics.ObserveDenied("EU")
+	metrics.ObserveAttempt("APAC")
+	var output strings.Builder
+	if err := metrics.WritePrometheus(&output); err != nil {
+		t.Fatal(err)
+	}
+	text := output.String()
+	for _, fragment := range []string{
+		`cosmic_clash_allocator_allocation_attempts_total{region="EU"} 1`,
+		`cosmic_clash_allocator_allocations_total{region="EU"} 1`,
+		`cosmic_clash_allocator_allocation_failures_total{region="EU"} 1`,
+		`cosmic_clash_allocator_quota_denials_total{region="EU"} 1`,
+		`region="NA"`,
+	} {
+		if !strings.Contains(text, fragment) {
+			t.Fatalf("metrics missing %q: %s", fragment, text)
+		}
+	}
+	if strings.Contains(text, "APAC") {
+		t.Fatal("unbounded region label escaped into metrics")
+	}
+}
+
+func TestNilMetricsAreSafe(t *testing.T) {
+	var metrics *Metrics
+	metrics.ObserveAttempt("EU")
+	if err := metrics.WritePrometheus(&strings.Builder{}); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestMetricsHandlerIsReadOnlyAndScoped(t *testing.T) {
+	metrics := NewMetrics()
+	metrics.ObserveAttempt("NA")
+	handler := MetricsHandler(metrics)
+	get := httptest.NewRecorder()
+	handler.ServeHTTP(get, httptest.NewRequest(http.MethodGet, "/metrics", nil))
+	if get.Code != http.StatusOK || !strings.Contains(get.Body.String(), `region="NA"`) {
+		t.Fatalf("GET /metrics status=%d body=%s", get.Code, get.Body.String())
+	}
+	post := httptest.NewRecorder()
+	handler.ServeHTTP(post, httptest.NewRequest(http.MethodPost, "/metrics", nil))
+	if post.Code != http.StatusMethodNotAllowed {
+		t.Fatalf("POST /metrics status=%d, want 405", post.Code)
+	}
+}