Add obsx library

metrics_test.go

@@ -0,0 +1,64 @@
+package obsx
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestMetrics_Counter(t *testing.T) {
+	m := NewMetrics(MetricsConfig{Namespace: "test"})
+	c := m.Counter("requests_total", "Total requests", "method")
+	c.WithLabelValues("GET").Inc()
+	c.WithLabelValues("GET").Inc()
+	c.WithLabelValues("POST").Inc()
+
+	body := scrape(t, m)
+	if !strings.Contains(body, `test_requests_total{method="GET"} 2`) {
+		t.Errorf("expected GET counter=2, got:\n%s", body)
+	}
+	if !strings.Contains(body, `test_requests_total{method="POST"} 1`) {
+		t.Errorf("expected POST counter=1, got:\n%s", body)
+	}
+}
+
+func TestMetrics_Histogram(t *testing.T) {
+	m := NewMetrics(MetricsConfig{Namespace: "test"})
+	h := m.Histogram("duration_seconds", "Duration", nil, "op")
+	h.WithLabelValues("query").Observe(0.1)
+
+	body := scrape(t, m)
+	if !strings.Contains(body, "test_duration_seconds") {
+		t.Errorf("expected histogram, got:\n%s", body)
+	}
+}
+
+func TestMetrics_Gauge(t *testing.T) {
+	m := NewMetrics(MetricsConfig{Namespace: "test"})
+	g := m.Gauge("connections", "Active connections", "pool")
+	g.WithLabelValues("main").Set(42)
+
+	body := scrape(t, m)
+	if !strings.Contains(body, `test_connections{pool="main"} 42`) {
+		t.Errorf("expected gauge=42, got:\n%s", body)
+	}
+}
+
+func TestMetrics_Handler(t *testing.T) {
+	m := NewMetrics(MetricsConfig{})
+	handler := m.Handler()
+	if handler == nil {
+		t.Fatal("Handler returned nil")
+	}
+}
+
+func scrape(t *testing.T, m *Metrics) string {
+	t.Helper()
+	w := httptest.NewRecorder()
+	r, _ := http.NewRequest("GET", "/metrics", nil)
+	m.Handler().ServeHTTP(w, r)
+	body, _ := io.ReadAll(w.Body)
+	return string(body)
+}