From 0b95214f2ce8a8a04ed38c2c78ab44dc039d70b9 Mon Sep 17 00:00:00 2001
From: "Manu Mtz.-Almeida" <manu.mtza@gmail.com>
Date: Sat, 3 Feb 2018 08:23:05 +0100
Subject: [PATCH] test(virtual-scroll): adds more tests

---
 .../test/virtual-scroll-utils.spec.ts         | 19 ++++++++++++++++--
 .../virtual-scroll/virtual-scroll.tsx         | 20 +++++++++----------
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/packages/core/src/components/virtual-scroll/test/virtual-scroll-utils.spec.ts b/packages/core/src/components/virtual-scroll/test/virtual-scroll-utils.spec.ts
index 607dd9a2b2..affbbe0397 100644
--- a/packages/core/src/components/virtual-scroll/test/virtual-scroll-utils.spec.ts
+++ b/packages/core/src/components/virtual-scroll/test/virtual-scroll-utils.spec.ts
@@ -1,4 +1,4 @@
-import { CellType, HeaderFn, ItemHeightFn, VirtualNode, calcCells, calcHeightIndex, getRange, getViewport, resizeBuffer, updateVDom, ItemRenderFn, Range, getShouldUpdate } from '../virtual-scroll-utils';
+import { CellType, HeaderFn, ItemHeightFn, VirtualNode, calcCells, calcHeightIndex, getRange, getViewport, resizeBuffer, updateVDom, ItemRenderFn, Range, getShouldUpdate, positionForIndex } from '../virtual-scroll-utils';
 
 
 describe('getViewport', () => {
@@ -351,6 +351,21 @@ describe('getShouldUpdate', () => {
   });
 });
 
+describe('positionForIndex', () => {
+  it('should return the correct position', () => {
+    const items = [1, 2, 3, 4];
+    const {cells, heightIndex} = mockVirtualScroll(items,
+      () => 40,
+      (_, i) => i === 1 ? 'hola' : null,
+      (_, i) => i === 2 ? 'hola' : null
+    );
+    expect(positionForIndex(0, cells, heightIndex)).toEqual(0);
+    expect(positionForIndex(1, cells, heightIndex)).toEqual(50);
+    expect(positionForIndex(2, cells, heightIndex)).toEqual(90);
+    expect(positionForIndex(3, cells, heightIndex)).toEqual(140);
+  });
+});
+
 describe('updateVDom', () => {
   it('should initialize empty VDOM', () => {
     const vdom: VirtualNode[] = [];
@@ -491,7 +506,7 @@ function mockVirtualScroll(
   headerFn: HeaderFn = null,
   footerFn: HeaderFn = null
 ) {
-  const cells = calcCells(items, itemHeight, headerFn, footerFn, 10, 20, 30);
+  const cells = calcCells(items, itemHeight, headerFn, footerFn, 10, 10, 30);
   const heightIndex = resizeBuffer(null, cells.length);
   calcHeightIndex(heightIndex, cells, 0);
   return { items, heightIndex, cells };
diff --git a/packages/core/src/components/virtual-scroll/virtual-scroll.tsx b/packages/core/src/components/virtual-scroll/virtual-scroll.tsx
index 1ba62dff0c..c5aacd0f2f 100644
--- a/packages/core/src/components/virtual-scroll/virtual-scroll.tsx
+++ b/packages/core/src/components/virtual-scroll/virtual-scroll.tsx
@@ -180,20 +180,18 @@ export class VirtualScroll {
         this.virtualDom,
         heightIndex,
         this.cells,
-        range);
+        range
+      );
 
-      this.fireDomUpdate();
+      // write DOM
+      if (this.itemRender) {
+        doRender(this.el, this.itemRender, this.virtualDom, this.updateCellHeight.bind(this), this.totalHeight);
+      } else if (this.domRender) {
+        this.domRender(this.virtualDom, this.totalHeight);
+      }
     });
   }
 
-  private fireDomUpdate() {
-    if (this.itemRender) {
-      doRender(this.el, this.itemRender, this.virtualDom, this.updateCellHeight.bind(this), this.totalHeight);
-    } else if (this.domRender) {
-      this.domRender(this.virtualDom, this.totalHeight);
-    }
-  }
-
   private updateCellHeight(cell: Cell, node: HTMLElement) {
     (node as any).componentOnReady(() => {
       // let's give some additional time to read the height size
@@ -219,8 +217,8 @@ export class VirtualScroll {
       console.debug(`[${cell.reads}] cell size ${cell.height} -> ${height}`);
       cell.height = height;
       clearTimeout(this.timerUpdate);
-      this.indexDirty = Math.min(this.indexDirty, index);
       this.timerUpdate = setTimeout(() => this.updateVirtualScroll(), 100);
+      this.indexDirty = Math.min(this.indexDirty, index);
     }
   }