test(widgets): add unit tests for useTableState

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

@@ -0,0 +1,99 @@
+// ─────────────────────────────────────────────────────
+// @termuijs/widgets — Tests for useTableState
+// ─────────────────────────────────────────────────────
+
+import { describe, it, expect } from 'vitest';
+import { useTableState } from './TableState.js';
+import type { TableRow } from './Table.js';
+
+// ── Helpers ───────────────────────────────────────────
+
+const makeRow = (cells: string[]): TableRow => ({
+    cells,
+} as unknown as TableRow);
+
+const makeRows = (): TableRow[] => [
+    makeRow(['Alice', '30', 'Engineer']),
+    makeRow(['Bob',   '25', 'Designer']),
+    makeRow(['Carol', '35', 'Manager']),
+];
+
+// ── Tests ─────────────────────────────────────────────
+
+describe('useTableState', () => {
+
+    // ── initialization ────────────────────────────────
+
+    it('initializes with provided rows', () => {
+        const state = useTableState({ rows: makeRows() });
+        expect(state.rows).toHaveLength(3);
+    });
+
+    it('initializes scrollOffset to 0', () => {
+        const state = useTableState({ rows: makeRows() });
+        expect(state.scrollOffset).toBe(0);
+    });
+
+    // ── setRows ───────────────────────────────────────
+
+    it('setRows() updates the rows', () => {
+        const state = useTableState({ rows: makeRows() });
+        const newRows: TableRow[] = [makeRow(['Dave', '28', 'Dev'])];
+        state.setRows(newRows);
+        expect(state.rows).toHaveLength(1);
+        expect(state.rows[0].cells).toContain('Dave');
+    });
+
+    it('setRows() clamps scrollOffset when new list is shorter', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext();
+        state.scrollNext(); // scrollOffset = 2
+        state.setRows([makeRow(['Only', '1', 'Row'])]);
+        expect(state.scrollOffset).toBe(0);
+    });
+
+    it('setRows() keeps scrollOffset when still valid', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext(); // scrollOffset = 1
+        state.setRows(makeRows()); // same length
+        expect(state.scrollOffset).toBe(1);
+    });
+
+    it('setRows() resets scrollOffset to 0 on empty rows', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext();
+        state.setRows([]);
+        expect(state.scrollOffset).toBe(0);
+    });
+
+    // ── scrollNext ────────────────────────────────────
+
+    it('scrollNext() increments scrollOffset', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext();
+        expect(state.scrollOffset).toBe(1);
+    });
+
+    it('scrollNext() increments multiple times', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext();
+        state.scrollNext();
+        expect(state.scrollOffset).toBe(2);
+    });
+
+    // ── scrollPrev ────────────────────────────────────
+
+    it('scrollPrev() decrements scrollOffset', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollNext();
+        state.scrollNext(); // at 2
+        state.scrollPrev();
+        expect(state.scrollOffset).toBe(1);
+    });
+
+    it('scrollPrev() does not go below 0', () => {
+        const state = useTableState({ rows: makeRows() });
+        state.scrollPrev(); // already at 0
+        expect(state.scrollOffset).toBe(0);
+    });
+});