Add visual regression testing for RNTester

.github/workflow-scripts/__tests__/__fixtures__/visual.js

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+/**
+ * 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
+ */
+
+const SHA_A = 'a'.repeat(40);
+const SHA_B = 'b'.repeat(40);
+
+const ANDROID_ENVIRONMENT = {
+  apiLevel: 35,
+  abi: 'x86_64',
+  nativeBridge: 'libndk_translation.so',
+  systemImage:
+    'google/sdk_gphone64_x86_64/emu64xa:15/AE3A/1:userdebug/dev-keys',
+  screenSize: '1080x2400',
+  density: 420,
+  fontScale: '1.0',
+  locale: 'en-US',
+  animatorDurationScale: '0.0',
+  emulatorVersion: '37.2.12',
+};
+
+module.exports = {ANDROID_ENVIRONMENT, SHA_A, SHA_B};

.github/workflow-scripts/__tests__/visual-capture-test.js

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+/**
+ * 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
+ */
+
+const {
+  collectFlows,
+  failedFlowsFromJUnit,
+  maestroArgs,
+} = require('../visual/capture');
+const {environmentKey} = require('../visual/manifest');
+const {ANDROID_ENVIRONMENT} = require('./__fixtures__/visual');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+describe('visual capture', () => {
+  let directory;
+
+  beforeEach(() => {
+    directory = fs.mkdtempSync(path.join(os.tmpdir(), 'visual-test-'));
+  });
+
+  afterEach(() => {
+    fs.rmSync(directory, {recursive: true, force: true});
+  });
+
+  describe('environmentKey', () => {
+    test('is readable and stable', () => {
+      expect(environmentKey('android', ANDROID_ENVIRONMENT)).toMatch(
+        /^android-api35-x86-64-1080x2400-420dpi-[0-9a-f]{8}$/,
+      );
+      expect(environmentKey('android', {...ANDROID_ENVIRONMENT})).toBe(
+        environmentKey('android', ANDROID_ENVIRONMENT),
+      );
+    });
+
+    test.each([
+      ['fontScale', '1.15'],
+      ['emulatorVersion', '37.3.1'],
+    ])('changes when %s drifts', (property, value) => {
+      expect(
+        environmentKey('android', {...ANDROID_ENVIRONMENT, [property]: value}),
+      ).not.toBe(environmentKey('android', ANDROID_ENVIRONMENT));
+    });
+
+    test('ignores properties that are only recorded', () => {
+      expect(
+        environmentKey('ios', {
+          runtime: 'iOS-26-2',
+          deviceType: 'iPhone-17-Pro',
+          appearance: 'light',
+          contentSizeCategory: 'large',
+          locale: 'en_US',
+          xcode: 'Xcode 26.2',
+        }),
+      ).toBe(
+        environmentKey('ios', {
+          runtime: 'iOS-26-2',
+          deviceType: 'iPhone-17-Pro',
+          appearance: 'light',
+          contentSizeCategory: 'large',
+          locale: 'en_US',
+          xcode: 'Xcode 26.3',
+        }),
+      );
+    });
+    test('names iOS keys by runtime and device', () => {
+      expect(
+        environmentKey('ios', {
+          runtime: 'iOS-26-2',
+          deviceType: 'iPhone-17-Pro',
+        }),
+      ).toMatch(/^ios-26-2-iphone-17-pro-[0-9a-f]{8}$/);
+    });
+  });
+
+  describe('capture', () => {
+    test('collects top-level flows in order and ignores other files', () => {
+      fs.writeFileSync(path.join(directory, 'b.yml'), '');
+      fs.writeFileSync(path.join(directory, 'a.yaml'), '');
+      fs.writeFileSync(path.join(directory, 'notes.md'), '');
+      fs.mkdirSync(path.join(directory, 'helpers'));
+      fs.writeFileSync(path.join(directory, 'helpers/open.yml'), '');
+      expect(collectFlows(directory)).toEqual([
+        path.join(directory, 'a.yaml'),
+        path.join(directory, 'b.yml'),
+      ]);
+    });
+
+    test('rejects flows Maestro would report under the same name', () => {
+      fs.writeFileSync(path.join(directory, 'a.yml'), '');
+      fs.writeFileSync(path.join(directory, 'a.yaml'), '');
+      expect(() => collectFlows(directory)).toThrow("both report as 'a'");
+    });
+
+    test('reads failed flows from a Maestro JUnit report', () => {
+      const flows = ['/flows/text-a.yml', '/flows/text-b.yml', '/flows/c.yml'];
+      const report = [
+        '<testcase id="text-b" name="text-b" file="/flows/text-b.yml" status="ERROR">',
+        '<testcase id="text-a" name="text-a" file="/flows/text-a.yml" status="SUCCESS"/>',
+        '<testcase id="c" name="c" status="ERROR">',
+      ].join('\n');
+      expect(failedFlowsFromJUnit(report, flows)).toEqual([
+        '/flows/text-b.yml',
+        '/flows/c.yml',
+      ]);
+      expect(() =>
+        failedFlowsFromJUnit('<testcase name="other" status="ERROR">', flows),
+      ).toThrow("unknown flow 'other'");
+      expect(failedFlowsFromJUnit('', flows)).toEqual([]);
+    });
+
+    test.each([
+      [1, undefined, false],
+      [2, 'UDID', true],
+    ])('builds Maestro arguments for attempt %d', (attempt, udid, reuse) => {
+      const args = maestroArgs({
+        flows: ['/f/a.yml', '/f/b.yml'],
+        appId: 'com.example',
+        outputDir: '/out',
+        reportPath: '/r.xml',
+        udid,
+        attempt,
+      });
+      expect(
+        args.slice(args.indexOf('test'), args.indexOf('test') + 3),
+      ).toEqual(['test', '/f/a.yml', '/f/b.yml']);
+      expect(args).toEqual(
+        expect.arrayContaining([
+          '--format=junit',
+          '--output=/r.xml',
+          'APP_ID=com.example',
+          'VISUAL_OUTPUT_DIR=/out',
+        ]),
+      );
+      expect(args.includes('--no-reinstall-driver')).toBe(reuse);
+      expect(args.includes('--udid=UDID')).toBe(udid != null);
+    });
+  });
+});