chore: Add extra unit test for coverage

src/internal/item-container/__tests__/get-next-droppable.test.ts

@@ -0,0 +1,37 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+import { expect, test } from "vitest";
+import { Droppable } from "../../dnd-controller/controller";
+import { Rect } from "../../interfaces";
+import { getNextDroppable } from "../get-next-droppable";
+
+function getMockElement({ left, right, top, bottom }: Rect) {
+  return {
+    getBoundingClientRect: () => ({ left, right, top, bottom }),
+    ownerDocument: {
+      defaultView: {
+        pageXOffset: 0,
+        pageYOffset: 0,
+      },
+    },
+  } as HTMLElement;
+}
+
+test("returns null if there are no droppables", () => {
+  const elementMock = getMockElement({ left: 0, right: 0, top: 0, bottom: 0 });
+  expect(getNextDroppable(elementMock, [], "left")).toBe(null);
+});
+
+test("returns next droppable matching the direction", () => {
+  const elementMock = getMockElement({ left: 6, right: 4, top: 0, bottom: 0 });
+  const next = getNextDroppable(
+    elementMock,
+    [
+      ["1", { element: getMockElement({ left: 0, right: 10, top: 0, bottom: 0 }) } as Droppable],
+      ["2", { element: getMockElement({ left: 5, right: 5, top: 0, bottom: 0 }) } as Droppable],
+      ["3", { element: getMockElement({ left: 10, right: 0, top: 0, bottom: 0 }) } as Droppable],
+    ],
+    "right"
+  );
+  expect(next).toBe("2");
+});