fixes

pkg/cart/mutation_remove_item_test.go

@@ -0,0 +1,70 @@
+package cart
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"git.k6n.net/go-cart-actor/pkg/actor"
+	cart_messages "git.k6n.net/go-cart-actor/proto/cart"
+	"google.golang.org/protobuf/proto"
+)
+
+// Removing a parent line cascades to its child sub-articles, while unrelated
+// lines are left untouched.
+func TestRemoveItem_CascadesToChildren(t *testing.T) {
+	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
+	g := NewCartGrain(1, time.Now())
+	ctx := context.Background()
+
+	// Parent (line 1) + two children (lines 2,3) + an unrelated item (line 4).
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000})
+	parentLine := g.Items[0].Id
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 101, Sku: "C1", Quantity: 1, Price: 100, ParentId: &parentLine})
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 102, Sku: "C2", Quantity: 1, Price: 200, ParentId: &parentLine})
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 200, Sku: "OTHER", Quantity: 1, Price: 300})
+
+	if len(g.Items) != 4 {
+		t.Fatalf("setup: items = %d, want 4", len(g.Items))
+	}
+
+	if _, err := reg.Apply(ctx, g, &cart_messages.RemoveItem{Id: parentLine}); err != nil {
+		t.Fatalf("remove parent: %v", err)
+	}
+
+	if len(g.Items) != 1 {
+		t.Fatalf("after remove: items = %d, want 1 (only the unrelated line)", len(g.Items))
+	}
+	if g.Items[0].Sku != "OTHER" {
+		t.Errorf("remaining item sku = %q, want OTHER", g.Items[0].Sku)
+	}
+}
+
+// Removing a child leaves the parent and siblings intact.
+func TestRemoveItem_ChildDoesNotRemoveParent(t *testing.T) {
+	reg := NewCartMultationRegistry(NewCartMutationContext(nil))
+	g := NewCartGrain(1, time.Now())
+	ctx := context.Background()
+
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 100, Sku: "P", Quantity: 1, Price: 1000})
+	parentLine := g.Items[0].Id
+	mustApply(t, reg, g, &cart_messages.AddItem{ItemId: 101, Sku: "C1", Quantity: 1, Price: 100, ParentId: &parentLine})
+	childLine := g.Items[1].Id
+
+	if _, err := reg.Apply(ctx, g, &cart_messages.RemoveItem{Id: childLine}); err != nil {
+		t.Fatalf("remove child: %v", err)
+	}
+	if len(g.Items) != 1 {
+		t.Fatalf("items = %d, want 1 (parent remains)", len(g.Items))
+	}
+	if g.Items[0].Id != parentLine {
+		t.Errorf("remaining line = %d, want parent %d", g.Items[0].Id, parentLine)
+	}
+}
+
+func mustApply(t *testing.T, reg actor.MutationRegistry, g *CartGrain, m proto.Message) {
+	t.Helper()
+	if _, err := reg.Apply(context.Background(), g, m); err != nil {
+		t.Fatalf("apply %T: %v", m, err)
+	}
+}