From 966f97acdcbab2ada689528cffdba60ce3d2779a Mon Sep 17 00:00:00 2001
From: Nick Gerleman <ngerlem@meta.com>
Date: Tue, 15 Aug 2023 21:56:25 -0700
Subject: [PATCH] ListMetricAggregator UTs - cached measurement adjustment
 after layout changes (#38936)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38936

Unit tests that validate we continue to return correct measurement results through the lifetime of the list when cells are unmounted, or layout of the list shifts.

Changelog: [Internal]

Reviewed By: lenaic

Differential Revision: D47978632

fbshipit-source-id: b700fafb699e8820de6825f0ead1ef02c6d8f168
---
 .../__tests__/ListMetricsAggregator-test.js   | 182 ++++++++++++++++++
 1 file changed, 182 insertions(+)

diff --git a/packages/virtualized-lists/Lists/__tests__/ListMetricsAggregator-test.js b/packages/virtualized-lists/Lists/__tests__/ListMetricsAggregator-test.js
index d36930d9b01..ef253fb9463 100644
--- a/packages/virtualized-lists/Lists/__tests__/ListMetricsAggregator-test.js
+++ b/packages/virtualized-lists/Lists/__tests__/ListMetricsAggregator-test.js
@@ -712,4 +712,186 @@ describe('ListMetricsAggregator', () => {
       offset: 30,
     });
   });
+
+  it('resolves metrics of unmounted cell after list shift when using bottom-up layout propagation', () => {
+    const listMetrics = new ListMetricsAggregator();
+    const orientation = {horizontal: true, rtl: true};
+    const props: CellMetricProps = {
+      data: [1, 2, 3, 4, 5],
+      getItemCount: () => nullthrows(props.data).length,
+      getItem: (i: number) => nullthrows(props.data)[i],
+    };
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 0,
+      cellKey: '0',
+      orientation,
+      layout: {
+        height: 5,
+        width: 10,
+        x: 90,
+        y: 0,
+      },
+    });
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 1,
+      cellKey: '1',
+      orientation,
+      layout: {
+        height: 5,
+        width: 20,
+        x: 70,
+        y: 0,
+      },
+    });
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 100, height: 5},
+      orientation,
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: true,
+    });
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 2,
+      cellKey: '2',
+      orientation,
+      layout: {
+        height: 5,
+        width: 20,
+        x: 50,
+        y: 0,
+      },
+    });
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 120, height: 5},
+      orientation,
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: true,
+    });
+
+    listMetrics.notifyCellUnmounted('1');
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: false,
+    });
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 100, height: 5},
+      orientation,
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: false,
+    });
+  });
+
+  it('resolves metrics of unmounted cell after list shift when using top-down layout propagation', () => {
+    const listMetrics = new ListMetricsAggregator();
+    const orientation = {horizontal: true, rtl: true};
+    const props: CellMetricProps = {
+      data: [1, 2, 3, 4, 5],
+      getItemCount: () => nullthrows(props.data).length,
+      getItem: (i: number) => nullthrows(props.data)[i],
+    };
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 100, height: 5},
+      orientation,
+    });
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 0,
+      cellKey: '0',
+      orientation,
+      layout: {
+        height: 5,
+        width: 10,
+        x: 90,
+        y: 0,
+      },
+    });
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 1,
+      cellKey: '1',
+      orientation,
+      layout: {
+        height: 5,
+        width: 20,
+        x: 70,
+        y: 0,
+      },
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: true,
+    });
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 120, height: 5},
+      orientation,
+    });
+
+    listMetrics.notifyCellLayout({
+      cellIndex: 2,
+      cellKey: '2',
+      orientation,
+      layout: {
+        height: 5,
+        width: 20,
+        x: 50,
+        y: 0,
+      },
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: true,
+    });
+
+    listMetrics.notifyListContentLayout({
+      layout: {width: 100, height: 5},
+      orientation,
+    });
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: true,
+    });
+
+    listMetrics.notifyCellUnmounted('1');
+
+    expect(listMetrics.getCellMetrics(1, props)).toEqual({
+      index: 1,
+      length: 20,
+      offset: 10,
+      isMounted: false,
+    });
+  });
 });