Add API router, index

api/src/category.router.test.ts

@@ -0,0 +1,35 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { buildCategoryTree, CategoryNode } from './tree.utility.ts';
+
+describe('Tree Utility - buildCategoryTree()', () => {
+    it('should transform a flat list of ltree rows into a nested JSON structure', () => {
+        const flatNodes: CategoryNode[] = [
+            { id: 1, name: 'Root', path: 'Top' },
+            { id: 3, name: 'Astronomy', path: 'Top.Science.Astronomy' },
+            { id: 2, name: 'Science', path: 'Top.Science' },
+            { id: 4, name: 'Gardening', path: 'Top.Hobbies.Gardening' },
+            { id: 5, name: 'Hobbies', path: 'Top.Hobbies' }
+        ];
+
+        const tree = buildCategoryTree(flatNodes);
+
+        // Verify root nodes count
+        assert.equal(tree.length, 1);
+        assert.equal(tree[0].name, 'Root');
+
+        // Verify second level ("Science" and "Hobbies")
+        const rootChildren = tree[0].children;
+        assert.equal(rootChildren.length, 2);
+
+        const scienceNode = rootChildren.find(c => c.name === 'Science');
+        const hobbiesNode = rootChildren.find(c => c.name === 'Hobbies');
+
+        assert.ok(scienceNode);
+        assert.ok(hobbiesNode);
+
+        // Verify third level deeply nested child ("Astronomy")
+        assert.equal(scienceNode.children.length, 1);
+        assert.equal(scienceNode.children[0].name, 'Astronomy');
+    });
+});