Initial go port of epics

internal/metrics/metrics_test.go

@@ -0,0 +1,69 @@
+package metrics_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/uopi/uopi/internal/metrics"
+)
+
+func TestCounters(t *testing.T) {
+	// Counters are package-level atomics; exercise each Inc function.
+	metrics.IncWsConns()
+	metrics.IncWsConns()
+	metrics.DecWsConns()
+	metrics.IncMsgIn()
+	metrics.IncMsgOut()
+	metrics.IncWrites()
+	metrics.IncHistoryReqs()
+	// No panic = pass; values are additive across tests but that's fine.
+}
+
+func TestHandlerFormat(t *testing.T) {
+	handler := metrics.Handler(func() int { return 42 })
+
+	req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
+	rec := httptest.NewRecorder()
+	handler(rec, req)
+
+	body := rec.Body.String()
+
+	// Must contain all metric names.
+	required := []string{
+		"uopi_uptime_seconds",
+		"uopi_ws_connections",
+		"uopi_signal_subscriptions",
+		"uopi_ws_messages_in_total",
+		"uopi_ws_messages_out_total",
+		"uopi_write_ops_total",
+		"uopi_history_requests_total",
+	}
+	for _, name := range required {
+		if !strings.Contains(body, name) {
+			t.Errorf("metric %q not found in response body", name)
+		}
+	}
+
+	// Content-Type must be set for Prometheus scrapers.
+	ct := rec.Header().Get("Content-Type")
+	if !strings.Contains(ct, "text/plain") {
+		t.Errorf("Content-Type = %q, want text/plain", ct)
+	}
+
+	// activeSubs value 42 must appear.
+	if !strings.Contains(body, "42") {
+		t.Error("activeSubs value 42 not found in body")
+	}
+}
+
+func TestHandlerNilActiveSubs(t *testing.T) {
+	handler := metrics.Handler(nil)
+	req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
+	rec := httptest.NewRecorder()
+	handler(rec, req) // must not panic
+	if rec.Code != http.StatusOK {
+		t.Errorf("status = %d, want 200", rec.Code)
+	}
+}