1 files changed, 36 insertions, 0 deletions
diff --git a/spec/frontend/shared/toc/flatten_items_spec.js b/spec/frontend/shared/toc/flatten_items_spec.js
new file mode 100644
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+++ b/spec/frontend/shared/toc/flatten_items_spec.js
@@ -0,0 +1,36 @@
+import { flattenItems } from '../../../../content/frontend/shared/toc/flatten_items';
+
+describe('shared/toc/flatten_items', () => {
+  const createItem = (text, ...items) => Object.assign({ text }, items ? { items } : {});
+  const createItemWithLevel = (text, level) => ({ text, level });
+
+  it.each`
+    desc                        | items                                  | expected
+    ${'empty'}                  | ${[]}                                  | ${[]}
+    ${'single item'}            | ${[createItem('a')]}                   | ${[createItemWithLevel('a', 0)]}
+    ${'single item with child'} | ${[createItem('a', createItem('a1'))]} | ${[createItemWithLevel('a', 0), createItemWithLevel('a1', 1)]}
+  `('with items is $desc and level=$level', ({ items, expected }) => {
+    expect(flattenItems(items)).toEqual(expected);
+  });
+
+  it('with multiple items', () => {
+    const items = [
+      createItem('a', createItem('a1')),
+      createItem('b'),
+      createItem('c', createItem('c1'), createItem('c2', createItem('c21')), createItem('c3')),
+    ];
+
+    const expectedItems = [
+      createItemWithLevel('a', 1),
+      createItemWithLevel('a1', 2),
+      createItemWithLevel('b', 1),
+      createItemWithLevel('c', 1),
+      createItemWithLevel('c1', 2),
+      createItemWithLevel('c2', 2),
+      createItemWithLevel('c21', 3),
+      createItemWithLevel('c3', 2),
+    ];
+
+    expect(flattenItems(items, 1)).toEqual(expectedItems);
+  });
+});