feat: add toHierarchy utility for TreeView, RecursiveList (#2072)

Co-authored-by: Bram <bramhavers@gmail.com>

tests/TreeView/toHierarchy.test.ts

@@ -0,0 +1,105 @@
+import { toHierarchy } from "../../src/utils/toHierarchy";
+
+describe("toHierarchy", () => {
+  test("should create a flat hierarchy when no items have parents", () => {
+    const input = [
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2", parentId: "invalid" },
+    ];
+    const result = toHierarchy(input, (item) => item.parentId);
+
+    expect(result).toEqual([
+      { id: 1, name: "Item 1" },
+      { id: 2, name: "Item 2", parentId: "invalid" },
+    ]);
+  });
+
+  test("should create a nested hierarchy with parent-child relationships", () => {
+    const input = [
+      { id: 1, name: "Parent" },
+      { id: 2, name: "Child", pid: 1, randomKey: "randomValue" },
+      { id: 3, name: "Grandchild", pid: 2 },
+    ];
+    const result = toHierarchy(input, (item) => item.pid);
+
+    expect(result).toEqual([
+      {
+        id: 1,
+        name: "Parent",
+        nodes: [
+          {
+            id: 2,
+            name: "Child",
+            pid: 1,
+            nodes: [
+              {
+                id: 3,
+                name: "Grandchild",
+                pid: 2,
+              },
+            ],
+            randomKey: "randomValue",
+          },
+        ],
+      },
+    ]);
+  });
+
+  test("should handle multiple root nodes with children", () => {
+    const input = [
+      { id: 1, name: "Root 1" },
+      { id: 2, name: "Root 2" },
+      { id: 3, name: "Child 1", pid: 1 },
+      { id: 4, name: "Child 2", pid: 2 },
+    ];
+    const result = toHierarchy(input, (item) => item.pid);
+
+    expect(result).toEqual([
+      {
+        id: 1,
+        name: "Root 1",
+        nodes: [
+          {
+            id: 3,
+            name: "Child 1",
+            pid: 1,
+          },
+        ],
+      },
+      {
+        id: 2,
+        name: "Root 2",
+        nodes: [
+          {
+            id: 4,
+            name: "Child 2",
+            pid: 2,
+          },
+        ],
+      },
+    ]);
+  });
+
+  test("should remove empty nodes arrays", () => {
+    const input = [
+      { id: 1, name: "Root" },
+      { id: 2, name: "Leaf", pid: 1 },
+    ];
+    const result = toHierarchy(input, (item) => item.pid);
+    expect(result).toEqual([
+      {
+        id: 1,
+        name: "Root",
+        nodes: [
+          {
+            id: 2,
+            name: "Leaf",
+            pid: 1,
+          },
+        ],
+      },
+    ]);
+
+    expect(result[0].nodes?.[0]).not.toHaveProperty("nodes");
+  });
+});