93 lines
3.0 KiB
TypeScript
93 lines
3.0 KiB
TypeScript
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import assert from 'node:assert/strict';
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import test from 'node:test';
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import {
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buildItemIndexToVisualIndexMap,
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clampListIndex,
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clampScrollTop,
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getFixedSizeVirtualWindow,
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stepListIndex,
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} from './virtualListMath.ts';
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test('clampScrollTop keeps the window on-content after a deep scroll + filter shrink', () => {
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// User was deep in a long list (scrollTop large), then filter leaves few rows.
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assert.equal(clampScrollTop(50_000, 10 * 44, 360), Math.max(0, 10 * 44 - 360));
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assert.equal(clampScrollTop(-10, 1000, 200), 0);
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assert.equal(clampScrollTop(100, 1000, 200), 100);
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assert.equal(clampScrollTop(0, 0, 200), 0);
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});
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test('getFixedSizeVirtualWindow never starts past the last item after shrink', () => {
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const deep = getFixedSizeVirtualWindow({
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itemCount: 10_000,
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itemHeight: 44,
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scrollTop: 40_000,
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viewportHeight: 300,
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overscan: 6,
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});
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assert.ok(deep.startIndex < 10_000);
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assert.ok(deep.endIndex - deep.startIndex < 100);
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assert.ok(deep.endIndex <= 10_000);
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const shrunk = getFixedSizeVirtualWindow({
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itemCount: 8,
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itemHeight: 44,
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scrollTop: 40_000,
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viewportHeight: 300,
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overscan: 6,
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});
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assert.equal(shrunk.effectiveScrollTop, Math.max(0, 8 * 44 - 300));
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assert.ok(shrunk.startIndex >= 0);
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assert.ok(shrunk.startIndex < 8);
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assert.equal(shrunk.endIndex, 8);
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// Window must include at least one real item so the list never blanks.
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assert.ok(shrunk.endIndex > shrunk.startIndex);
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});
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test('getFixedSizeVirtualWindow only materializes a viewport-sized slice for large lists', () => {
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const window = getFixedSizeVirtualWindow({
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itemCount: 8_000,
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itemHeight: 44,
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scrollTop: 0,
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viewportHeight: 360,
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overscan: 8,
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});
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const rendered = window.endIndex - window.startIndex;
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assert.ok(rendered > 0);
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assert.ok(rendered < 100, `expected viewport window, got ${rendered}`);
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assert.equal(window.startIndex, 0);
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});
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test('clampListIndex and stepListIndex never produce -1 on empty or non-empty lists', () => {
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assert.equal(clampListIndex(-1, 0), 0);
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assert.equal(clampListIndex(5, 0), 0);
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assert.equal(clampListIndex(-1, 5), 0);
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assert.equal(clampListIndex(99, 5), 4);
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assert.equal(clampListIndex(2, 5), 2);
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assert.equal(stepListIndex(0, 0, 1), 0);
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assert.equal(stepListIndex(0, 0, -1), 0);
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// Empty list + ArrowDown must not go to -1 (QuickSwitcher regression).
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assert.equal(stepListIndex(0, 0, 1), 0);
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assert.equal(stepListIndex(0, 3, 1), 1);
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assert.equal(stepListIndex(2, 3, 1), 2);
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assert.equal(stepListIndex(0, 3, -1), 0);
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});
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test('buildItemIndexToVisualIndexMap skips headers for keyboard scroll targets', () => {
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const visual = [
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{ kind: 'header' },
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{ kind: 'item' },
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{ kind: 'item' },
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{ kind: 'header' },
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{ kind: 'item' },
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];
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const map = buildItemIndexToVisualIndexMap(visual);
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assert.equal(map.get(0), 1);
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assert.equal(map.get(1), 2);
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assert.equal(map.get(2), 4);
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assert.equal(map.size, 3);
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// Keyboard index 1 scrolls to visual row 2 (second host, after first header).
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assert.notEqual(map.get(1), 1);
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});
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