more

internal/features/spike_test.go

@@ -0,0 +1,41 @@
+package features
+
+import (
+	"testing"
+	"time"
+)
+
+func TestDetectSpikesIgnoresChronicPatterns(t *testing.T) {
+	at := time.Date(2026, 9, 19, 12, 0, 0, 0, time.UTC)
+	cfg := SpikeConfig{Window: 5 * time.Minute, BaselineWindows: 12}
+	var events []Event
+	add := func(sig string, n int, when time.Time) {
+		for i := 0; i < n; i++ {
+			events = append(events, Event{Timestamp: when.Add(time.Duration(i) * time.Second), Service: "api", IsError: true, PatternSignature: sig})
+		}
+	}
+	// chronic poller: 50 errors in every window, including the current one
+	for w := 0; w <= 12; w++ {
+		add("poll-401", 50, at.Add(-time.Duration(w+1)*cfg.Window))
+	}
+	if got := DetectSpikes(events, at, cfg); len(got) != 0 {
+		t.Fatalf("chronic pattern alone alerted: %+v", got)
+	}
+	// a novel failure appears in the current window
+	add("db-timeout", 20, at.Add(-cfg.Window))
+	got := DetectSpikes(events, at, cfg)
+	if len(got) != 1 || got[0].Patterns[0].Signature != "db-timeout" || !got[0].Patterns[0].Novel {
+		t.Fatalf("expected db-timeout spike, got %+v", got)
+	}
+}
+
+func TestDetectSpikesRequiresMinimumExcess(t *testing.T) {
+	at := time.Date(2026, 9, 19, 12, 0, 0, 0, time.UTC)
+	events := []Event{}
+	for i := 0; i < 3; i++ {
+		events = append(events, Event{Timestamp: at.Add(-time.Minute), Service: "api", IsError: true, PatternSignature: "x"})
+	}
+	if got := DetectSpikes(events, at, SpikeConfig{}); len(got) != 0 {
+		t.Fatalf("3 errors should stay under the floor: %+v", got)
+	}
+}