test: add unit tests for useListState functionality

packages/widgets/src/data/ListState.test.ts

@@ -0,0 +1,136 @@
+// ─────────────────────────────────────────────────────
+// @termuijs/widgets — Tests for useListState
+// ─────────────────────────────────────────────────────
+
+import { describe, it, expect } from 'vitest';
+import { useListState } from './ListState.js';
+import type { ListItem } from '../input/List.js';
+
+// ── Helpers ───────────────────────────────────────────
+
+const makeItems = (): ListItem[] => [
+    { label: 'Apple',  value: 'apple'  },
+    { label: 'Banana', value: 'banana' },
+    { label: 'Cherry', value: 'cherry' },
+];
+
+const makeItemsWithDisabled = (): ListItem[] => [
+    { label: 'Apple',  value: 'apple'  },
+    { label: 'Banana', value: 'banana', disabled: true },
+    { label: 'Cherry', value: 'cherry' },
+];
+
+// ── Tests ─────────────────────────────────────────────
+
+describe('useListState', () => {
+
+    // ── initialization ────────────────────────────────
+
+    it('initializes with provided items', () => {
+        const state = useListState({ items: makeItems() });
+        expect(state.items).toHaveLength(3);
+    });
+
+    it('initializes selectedIndex to 0', () => {
+        const state = useListState({ items: makeItems() });
+        expect(state.selectedIndex).toBe(0);
+    });
+
+    it('initializes scrollOffset to 0', () => {
+        const state = useListState({ items: makeItems() });
+        expect(state.scrollOffset).toBe(0);
+    });
+
+    // ── setItems ──────────────────────────────────────
+
+    it('setItems() updates the items list', () => {
+        const state = useListState({ items: makeItems() });
+        const newItems: ListItem[] = [{ label: 'Mango', value: 'mango' }];
+        state.setItems(newItems);
+        expect(state.items).toHaveLength(1);
+        expect(state.items[0].value).toBe('mango');
+    });
+
+    it('setItems() clamps selectedIndex when new list is shorter', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        state.selectNext(); // selectedIndex = 2
+        state.setItems([{ label: 'Only', value: 'only' }]);
+        expect(state.selectedIndex).toBe(0);
+    });
+
+    it('setItems() keeps selectedIndex when still valid', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext(); // selectedIndex = 1
+        state.setItems(makeItems()); // same length
+        expect(state.selectedIndex).toBe(1);
+    });
+
+    it('setItems() handles empty list and resets selectedIndex to 0', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        state.setItems([]);
+        expect(state.selectedIndex).toBe(0);
+    });
+
+    // ── selectNext ────────────────────────────────────
+
+    it('selectNext() moves selection forward', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        expect(state.selectedIndex).toBe(1);
+    });
+
+    it('selectNext() does not go past last item', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        state.selectNext();
+        state.selectNext(); // already at last
+        expect(state.selectedIndex).toBe(2);
+    });
+
+    it('selectNext() skips disabled items', () => {
+        const state = useListState({ items: makeItemsWithDisabled() });
+        state.selectNext(); // index 1 is disabled → skips to 2
+        expect(state.selectedIndex).toBe(2);
+    });
+
+    // ── selectPrev ────────────────────────────────────
+
+    it('selectPrev() moves selection backward', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        state.selectNext(); // at 2
+        state.selectPrev();
+        expect(state.selectedIndex).toBe(1);
+    });
+
+    it('selectPrev() does not go below 0', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectPrev(); // already at 0
+        expect(state.selectedIndex).toBe(0);
+    });
+
+    it('selectPrev() skips disabled items', () => {
+        const state = useListState({ items: makeItemsWithDisabled() });
+        state.selectNext(); // skips to index 2 (banana disabled)
+        state.selectPrev(); // index 1 is disabled → skips to 0
+        expect(state.selectedIndex).toBe(0);
+    });
+
+    it('selectPrev() updates scrollOffset when selection goes above it', () => {
+        const state = useListState({ items: makeItems() });
+        state.selectNext();
+        state.selectNext(); // at 2, scrollOffset still 0
+        state.scrollOffset = 2; // simulate scrolled down
+        state.selectPrev(); // goes to 1, which is < scrollOffset
+        expect(state.scrollOffset).toBe(1);
+    });
+
+    // ── confirm ───────────────────────────────────────
+
+    it('confirm() is callable without throwing', () => {
+        const state = useListState({ items: makeItems() });
+        expect(() => state.confirm()).not.toThrow();
+    });
+});