From dc7941d7327bc605ca92c16f8d8d484407912a96 Mon Sep 17 00:00:00 2001
From: Ruslan Shestopalyuk <rshest@meta.com>
Date: Tue, 14 Mar 2023 04:48:02 -0700
Subject: [PATCH] Shim implementation for NativePerformance on JS side

Summary:
Changelog: [Internal]

Implements a shim for the NativePerformance TurboModule, which can be used as a mock to unit test the JS side of WebPerformance functionality (in particular, the higher level API logic of `Performance` and `PerformanceObserver` implementations in JS) without need to have the native NativePerformance implementation available (which would otherwise require running some heavy weight e2e tests).

Reviewed By: rubennorte

Differential Revision: D43985454

fbshipit-source-id: da10387c1d70cb0300c077972d3925bc2fad4f5e
---
 .../__mocks__/NativePerformance.js            | 65 +++++++++++++++
 .../__tests__/NativePerformanceMock-test.js   | 82 +++++++++++++++++++
 2 files changed, 147 insertions(+)
 create mode 100644 Libraries/WebPerformance/__mocks__/NativePerformance.js
 create mode 100644 Libraries/WebPerformance/__tests__/NativePerformanceMock-test.js

diff --git a/Libraries/WebPerformance/__mocks__/NativePerformance.js b/Libraries/WebPerformance/__mocks__/NativePerformance.js
new file mode 100644
index 00000000000..6b11a27a20a
--- /dev/null
+++ b/Libraries/WebPerformance/__mocks__/NativePerformance.js
@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ */
+
+import type {
+  NativeMemoryInfo,
+  ReactNativeStartupTiming,
+  Spec as NativePerformance,
+} from '../NativePerformance';
+
+import NativePerformanceObserver from '../NativePerformanceObserver';
+import {RawPerformanceEntryTypeValues} from '../RawPerformanceEntry';
+
+const marks: Map<string, number> = new Map();
+
+const NativePerformanceMock: NativePerformance = {
+  mark: (name: string, startTime: number, duration: number): void => {
+    NativePerformanceObserver?.logRawEntry({
+      name,
+      entryType: RawPerformanceEntryTypeValues.MARK,
+      startTime,
+      duration,
+    });
+    marks.set(name, startTime);
+  },
+
+  measure: (
+    name: string,
+    startTime: number,
+    endTime: number,
+    duration?: number,
+    startMark?: string,
+    endMark?: string,
+  ): void => {
+    const start = startMark != null ? marks.get(startMark) ?? 0 : startTime;
+    const end = endMark != null ? marks.get(endMark) ?? 0 : endTime;
+    NativePerformanceObserver?.logRawEntry({
+      name,
+      entryType: RawPerformanceEntryTypeValues.MEASURE,
+      startTime: start,
+      duration: duration ?? (end ? end - start : 0),
+    });
+  },
+
+  getSimpleMemoryInfo: (): NativeMemoryInfo => {
+    return {};
+  },
+
+  getReactNativeStartupTiming: (): ReactNativeStartupTiming => {
+    return {
+      startTime: 0,
+      endTime: 0,
+      executeJavaScriptBundleEntryPointStart: 0,
+      executeJavaScriptBundleEntryPointEnd: 0,
+    };
+  },
+};
+
+export default NativePerformanceMock;
diff --git a/Libraries/WebPerformance/__tests__/NativePerformanceMock-test.js b/Libraries/WebPerformance/__tests__/NativePerformanceMock-test.js
new file mode 100644
index 00000000000..679dad39dfc
--- /dev/null
+++ b/Libraries/WebPerformance/__tests__/NativePerformanceMock-test.js
@@ -0,0 +1,82 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @oncall react_native
+ */
+
+const NativePerformanceMock = require('../__mocks__/NativePerformance').default;
+const PerformanceObserver = require('../PerformanceObserver').default;
+
+describe('NativePerformanceMock', () => {
+  jest.mock(
+    '../NativePerformanceObserver',
+    () => require('../__mocks__/NativePerformanceObserver').default,
+  );
+
+  it('marks get reported', async () => {
+    let entries = [];
+    const observer = new PerformanceObserver((list, _observer) => {
+      entries = [...entries, ...list.getEntries()];
+    });
+
+    observer.observe({type: 'mark'});
+
+    NativePerformanceMock.mark('mark1', 0, 10);
+    NativePerformanceMock.mark('mark2', 5, 10);
+    NativePerformanceMock.mark('mark3', 10, 20);
+
+    await jest.runAllTicks();
+    expect(entries).toHaveLength(3);
+    expect(entries.map(e => e.name)).toStrictEqual(['mark1', 'mark2', 'mark3']);
+    expect(entries.map(e => e.startTime)).toStrictEqual([0, 5, 10]);
+  });
+
+  it('measures get reported', async () => {
+    let entries = [];
+    const observer = new PerformanceObserver((list, _observer) => {
+      entries = [...entries, ...list.getEntries()];
+    });
+
+    observer.observe({entryTypes: ['measure']});
+
+    NativePerformanceMock.mark('mark0', 0.0, 1.0);
+    NativePerformanceMock.mark('mark1', 1.0, 3.0);
+    NativePerformanceMock.mark('mark2', 2.0, 4.0);
+
+    NativePerformanceMock.measure('measure0', 0, 2);
+    NativePerformanceMock.measure('measure1', 0, 2, 4);
+    NativePerformanceMock.measure(
+      'measure2',
+      0,
+      0,
+      undefined,
+      'mark1',
+      'mark2',
+    );
+    NativePerformanceMock.measure('measure3', 0, 0, 5, 'mark1');
+    NativePerformanceMock.measure(
+      'measure4',
+      1.5,
+      0,
+      undefined,
+      undefined,
+      'mark2',
+    );
+
+    await jest.runAllTicks();
+    expect(entries).toHaveLength(5);
+    expect(entries.map(e => e.name)).toStrictEqual([
+      'measure0',
+      'measure1',
+      'measure2',
+      'measure3',
+      'measure4',
+    ]);
+    expect(entries.map(e => e.startTime)).toStrictEqual([0, 0, 1, 1, 1.5]);
+    expect(entries.map(e => e.duration)).toStrictEqual([2, 4, 1, 5, 0.5]);
+  });
+});