internal: initial metrics aggregator

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I9cdd6e2b33bb65182568db9db4460bc46a6a6964

internal/aggregate/metrics_test.go

@@ -0,0 +1,192 @@
+package aggregate
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+	"notashelf.dev/watchdog/internal/config"
+)
+
+func TestMetricsAggregator_RecordPageview(t *testing.T) {
+	registry := NewPathRegistry(100)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+				Country:   true,
+				Device:    true,
+				Referrer:  "domain",
+			},
+		},
+	}
+
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Record pageview with all dimensions
+	agg.RecordPageview("/home", "US", "desktop", "google.com")
+
+	// Verify metric was recorded
+	expected := `
+# HELP web_pageviews_total Total number of pageviews
+# TYPE web_pageviews_total counter
+web_pageviews_total{country="US",device="desktop",path="/home",referrer="google.com"} 1
+`
+	if err := testutil.CollectAndCompare(agg.pageviews, strings.NewReader(expected)); err != nil {
+		t.Errorf("unexpected metric value: %v", err)
+	}
+}
+
+func TestMetricsAggregator_RecordPageview_MinimalDimensions(t *testing.T) {
+	registry := NewPathRegistry(100)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+				Country:   false,
+				Device:    false,
+				Referrer:  "off",
+			},
+		},
+	}
+
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Record pageview with only path
+	agg.RecordPageview("/home", "", "", "")
+
+	// Verify metric was recorded
+	expected := `
+# HELP web_pageviews_total Total number of pageviews
+# TYPE web_pageviews_total counter
+web_pageviews_total{path="/home"} 1
+`
+	if err := testutil.CollectAndCompare(agg.pageviews, strings.NewReader(expected)); err != nil {
+		t.Errorf("unexpected metric value: %v", err)
+	}
+}
+
+func TestMetricsAggregator_PathOverflow(t *testing.T) {
+	// Create registry with limit of 2
+	registry := NewPathRegistry(2)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+			},
+		},
+	}
+
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Add two paths successfully
+	registry.Add("/path1")
+	registry.Add("/path2")
+
+	// Try to add third path - should be rejected
+	if registry.Add("/path3") {
+		t.Error("expected path to be rejected")
+	}
+
+	// Record overflow
+	agg.RecordPathOverflow()
+
+	// Verify overflow metric
+	expected := `
+# HELP web_path_overflow_total Paths rejected due to cardinality limit
+# TYPE web_path_overflow_total counter
+web_path_overflow_total 1
+`
+	if err := testutil.CollectAndCompare(agg.pathOverflow, strings.NewReader(expected)); err != nil {
+		t.Errorf("unexpected metric value: %v", err)
+	}
+}
+
+func TestMetricsAggregator_RecordCustomEvent(t *testing.T) {
+	registry := NewPathRegistry(100)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+			},
+			CustomEvents: []string{"signup", "purchase"},
+		},
+	}
+
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Record custom event
+	agg.RecordCustomEvent("signup")
+
+	// Verify metric was recorded
+	expected := `
+# HELP web_custom_events_total Total number of custom events
+# TYPE web_custom_events_total counter
+web_custom_events_total{event="signup"} 1
+`
+	if err := testutil.CollectAndCompare(agg.customEvents, strings.NewReader(expected)); err != nil {
+		t.Errorf("unexpected metric value: %v", err)
+	}
+}
+
+func TestMetricsAggregator_RecordCustomEvent_MultipleEvents(t *testing.T) {
+	registry := NewPathRegistry(100)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+			},
+			CustomEvents: []string{"signup", "purchase"},
+		},
+	}
+
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Record multiple events
+	agg.RecordCustomEvent("signup")
+	agg.RecordCustomEvent("signup")
+	agg.RecordCustomEvent("purchase")
+
+	// Verify metrics
+	if err := testutil.CollectAndCompare(agg.customEvents, strings.NewReader(`
+# HELP web_custom_events_total Total number of custom events
+# TYPE web_custom_events_total counter
+web_custom_events_total{event="purchase"} 1
+web_custom_events_total{event="signup"} 2
+`)); err != nil {
+		t.Errorf("unexpected metric value: %v", err)
+	}
+}
+
+func TestMetricsAggregator_MustRegister(t *testing.T) {
+	registry := NewPathRegistry(100)
+	cfg := config.Config{
+		Site: config.SiteConfig{
+			Collect: config.CollectConfig{
+				Pageviews: true,
+			},
+		},
+	}
+
+	promRegistry := prometheus.NewRegistry()
+	agg := NewMetricsAggregator(registry, cfg)
+
+	// Register metrics
+	agg.MustRegister(promRegistry)
+
+	// Record some metrics to ensure they show up
+	agg.RecordPageview("/test", "", "", "")
+	agg.RecordPathOverflow()
+
+	// Verify metrics can be gathered
+	metrics, err := promRegistry.Gather()
+	if err != nil {
+		t.Fatalf("failed to gather metrics: %v", err)
+	}
+
+	// Should have at least pageviews and path overflow metrics
+	if len(metrics) < 2 {
+		t.Errorf("expected at least 2 metric families, got %d", len(metrics))
+	}
+}