fixes

pkg/cart/mutation_custom_fields_test.go

@@ -0,0 +1,65 @@
+package cart
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	cart_messages "git.k6n.net/go-cart-actor/proto/cart"
+)
+
+func TestAddItem_StoresCustomFields(t *testing.T) {
+	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
+	g := NewCartGrain(1, time.Now())
+
+	mustApply(t, reg, g, &cart_messages.AddItem{
+		ItemId: 100, Sku: "P", Quantity: 1, Price: 1000,
+		CustomFields: map[string]string{"engraving": "Happy Birthday", "color": "blue"},
+	})
+
+	if len(g.Items) != 1 {
+		t.Fatalf("items = %d, want 1", len(g.Items))
+	}
+	cf := g.Items[0].CustomFields
+	if cf["engraving"] != "Happy Birthday" || cf["color"] != "blue" {
+		t.Fatalf("custom fields = %v, want engraving+color", cf)
+	}
+}
+
+func TestSetLineItemCustomFields_Merges(t *testing.T) {
+	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
+	g := NewCartGrain(1, time.Now())
+
+	mustApply(t, reg, g, &cart_messages.AddItem{
+		ItemId: 100, Sku: "P", Quantity: 1, Price: 1000,
+		CustomFields: map[string]string{"engraving": "v1"},
+	})
+	line := g.Items[0].Id
+
+	// Upsert: overwrite "engraving", add "note", leave others alone.
+	mustApply(t, reg, g, &cart_messages.SetLineItemCustomFields{
+		Id:           line,
+		CustomFields: map[string]string{"engraving": "v2", "note": "gift wrap"},
+	})
+
+	cf := g.Items[0].CustomFields
+	if cf["engraving"] != "v2" {
+		t.Errorf("engraving = %q, want v2", cf["engraving"])
+	}
+	if cf["note"] != "gift wrap" {
+		t.Errorf("note = %q, want 'gift wrap'", cf["note"])
+	}
+}
+
+func TestSetLineItemCustomFields_UnknownItem(t *testing.T) {
+	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
+	g := NewCartGrain(1, time.Now())
+	// The handler error is reported per-mutation in the ApplyResult (the
+	// registry only returns a top-level error for unregistered mutations).
+	results, _ := reg.Apply(context.Background(), g, &cart_messages.SetLineItemCustomFields{
+		Id: 999, CustomFields: map[string]string{"x": "y"},
+	})
+	if len(results) != 1 || results[0].Error == nil {
+		t.Errorf("expected per-mutation error for unknown item id, got %+v", results)
+	}
+}