CosmicClash/server/allocator/metrics_test.go

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)
	}
}