Moved generic and broadly useful helper functions upstream into feedkit

internal/normalizers/common/finalize_test.go

@@ -0,0 +1,36 @@
+package common
+
+import (
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestFinalizeRoundsWeatherPayloadFloats(t *testing.T) {
+	type payload struct {
+		Value float64
+	}
+
+	in := event.Event{
+		ID:        "evt-1",
+		Kind:      event.Kind("observation"),
+		Source:    "source-a",
+		EmittedAt: time.Date(2026, 3, 28, 12, 0, 0, 0, time.UTC),
+		Schema:    "raw.example.v1",
+		Payload:   map[string]any{"old": true},
+	}
+
+	out, err := Finalize(in, "weather.example.v1", payload{Value: 1.234567}, time.Time{})
+	if err != nil {
+		t.Fatalf("Finalize() unexpected error: %v", err)
+	}
+
+	got, ok := out.Payload.(payload)
+	if !ok {
+		t.Fatalf("Finalize() payload type = %T, want payload", out.Payload)
+	}
+	if got.Value != 1.2346 {
+		t.Fatalf("Finalize() rounded value = %v, want 1.2346", got.Value)
+	}
+}