Try normalizing TZ across environments instead of changing the previewed string

Author: eps1lon

packages/react-devtools-shared/src/__tests__/dehydratedValueSerializer.js

@@ -22,18 +22,6 @@ export function test(maybeDehydratedValue) {
   );
 }
 
-function serializeDehydratedValuePreview(preview) {
-  const date = new Date(preview);
-  const isDatePreview = !Number.isNaN(date.valueOf());
-  if (isDatePreview) {
-    // The preview is just `String(date)` which formats the date in the local timezone.
-    // This results in a snapshot mismatch between tests run in e.g. GMT and ET
-    // WARNING: This does not guard against dates created with the default timezone i.e. the local timezone e.g. new Date('05 October 2011 14:48').
-    return date.toISOString();
-  }
-  return preview;
-}
-
 // print() is part of Jest's serializer API
 export function print(dehydratedValue, serialize, indent) {
   const {meta} = require('react-devtools-shared/src/hydration');
@@ -43,11 +31,11 @@ export function print(dehydratedValue, serialize, indent) {
     'Dehydrated {\n' +
     paddingLeft +
     '  "preview_short": ' +
-    serializeDehydratedValuePreview(dehydratedValue[meta.preview_short]) +
+    dehydratedValue[meta.preview_short] +
     ',\n' +
     paddingLeft +
     '  "preview_long": ' +
-    serializeDehydratedValuePreview(dehydratedValue[meta.preview_long]) +
+    dehydratedValue[meta.preview_long] +
     ',\n' +
     paddingLeft +
     '}'

scripts/jest/config.base.js

@@ -1,6 +1,7 @@
 'use strict';
 
 module.exports = {
+  globalSetup: require.resolve('./setupGlobal.js'),
   haste: {
     hasteImplModulePath: require.resolve('./noHaste.js'),
   },

scripts/jest/setupGlobal.js

@@ -0,0 +1,7 @@
+/* eslint-disable */
+
+module.exports = () => {
+  // can use beforeEach/afterEach or setupEnvironment.js in node >= 13: https://github.com/nodejs/node/pull/20026
+  // jest's `setupFiles` is too late: https://stackoverflow.com/a/56482581/3406963
+  process.env.TZ = 'UTC';
+};