Add timezone support (#20493)

eng/Version.Details.xml

@@ -9,9 +9,9 @@
 -->
 <Dependencies>
   <ProductDependencies>
-    <Dependency Name="Microsoft.AspNetCore.Components.WebAssembly.Runtime" Version="3.2.0-preview5.20210.3">
+    <Dependency Name="Microsoft.AspNetCore.Components.WebAssembly.Runtime" Version="3.2.0-preview5.20213.2">
       <Uri>https://github.com/dotnet/blazor</Uri>
-      <Sha>f429c0dd1a5dc84a70c66091460747d52475874f</Sha>
+      <Sha>e3ae74171b19c8dbd70e94cf8ac3024a1125479f</Sha>
     </Dependency>
     <Dependency Name="System.Net.Http.Json" Version="3.2.0-preview5.20210.3">
       <Uri>https://github.com/dotnet/corefx</Uri>

eng/Versions.props

@@ -99,7 +99,7 @@
     <!-- Only listed explicitly to workaround https://github.com/dotnet/cli/issues/10528 -->
     <MicrosoftNETCorePlatformsPackageVersion>3.1.0</MicrosoftNETCorePlatformsPackageVersion>
     <!-- Packages from aspnet/Blazor -->
-    <MicrosoftAspNetCoreComponentsWebAssemblyRuntimePackageVersion>3.2.0-preview5.20210.3</MicrosoftAspNetCoreComponentsWebAssemblyRuntimePackageVersion>
+    <MicrosoftAspNetCoreComponentsWebAssemblyRuntimePackageVersion>3.2.0-preview5.20213.2</MicrosoftAspNetCoreComponentsWebAssemblyRuntimePackageVersion>
     <!-- Packages from aspnet/Extensions -->
     <InternalAspNetCoreAnalyzersPackageVersion>3.1.3-servicing.20128.2</InternalAspNetCoreAnalyzersPackageVersion>
     <MicrosoftAspNetCoreAnalyzerTestingPackageVersion>3.1.3-servicing.20128.2</MicrosoftAspNetCoreAnalyzerTestingPackageVersion>

src/Components/Web.JS/src/BinaryDecoder.ts

@@ -0,0 +1,47 @@
+const uint64HighPartShift = Math.pow(2, 32);
+const maxSafeNumberHighPart = Math.pow(2, 21) - 1; // The high-order int32 from Number.MAX_SAFE_INTEGER
+
+export function readInt32LE(buffer: Uint8Array, position: number): any {
+    return (buffer[position])
+        | (buffer[position + 1] << 8)
+        | (buffer[position + 2] << 16)
+        | (buffer[position + 3] << 24);
+}
+
+export function readUint32LE(buffer: Uint8Array, position: number): any {
+    return (buffer[position])
+        + (buffer[position + 1] << 8)
+        + (buffer[position + 2] << 16)
+        + ((buffer[position + 3] << 24) >>> 0); // The >>> 0 coerces the value to unsigned
+}
+
+export function readUint64LE(buffer: Uint8Array, position: number): any {
+    // This cannot be done using bit-shift operators in JavaScript, because
+    // those all implicitly convert to int32
+    const highPart = readUint32LE(buffer, position + 4);
+    if (highPart > maxSafeNumberHighPart) {
+        throw new Error(`Cannot read uint64 with high order part ${highPart}, because the result would exceed Number.MAX_SAFE_INTEGER.`);
+    }
+
+    return (highPart * uint64HighPartShift) + readUint32LE(buffer, position);
+}
+
+export function readLEB128(buffer: Uint8Array, position: number) {
+    let result = 0;
+    let shift = 0;
+    for (let index = 0; index < 4; index++) {
+        const byte = buffer[position + index];
+        result |= (byte & 127) << shift;
+        if (byte < 128) {
+            break;
+        }
+        shift += 7;
+    }
+    return result;
+}
+
+export function numLEB128Bytes(value: number) {
+    return value < 128 ? 1
+        : value < 16384 ? 2
+            : value < 2097152 ? 3 : 4;
+}

src/Components/Web.JS/src/Platform/Mono/MonoPlatform.ts

@@ -2,6 +2,7 @@ import { attachDebuggerHotkey, hasDebuggingEnabled } from './MonoDebugger';
 import { showErrorNotification } from '../../BootErrors';
 import { WebAssemblyResourceLoader, LoadingResource } from '../WebAssemblyResourceLoader';
 import { Platform, System_Array, Pointer, System_Object, System_String } from '../Platform';
+import { loadTimezoneData } from './TimezoneDataFile';
 
 let mono_string_get_utf8: (managedString: System_String) => Pointer;
 let mono_wasm_add_assembly: (name: string, heapAddress: number, length: number) => void;
@@ -161,7 +162,7 @@ function addGlobalModuleScriptTagsToDocument(callback: () => void) {
 
 function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoader, onReady: () => void, onError: (reason?: any) => void) {
   const resources = resourceLoader.bootConfig.resources;
-  const module = {} as typeof Module;
+  const module = (window['Module'] || { }) as typeof Module;
   const suppressMessages = ['DEBUGGING ENABLED'];
 
   module.print = line => (suppressMessages.indexOf(line) < 0 && console.log(line));
@@ -170,8 +171,8 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
     console.error(line);
     showErrorNotification();
   };
-  module.preRun = [];
-  module.postRun = [];
+  module.preRun = module.preRun || [];
+  module.postRun = module.postRun || [];
   (module as any).preloadPlugins = [];
 
   // Begin loading the .dll/.pdb/.wasm files, but don't block here. Let other loading processes run in parallel.
@@ -183,6 +184,15 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
     /* url */  `_framework/wasm/${dotnetWasmResourceName}`,
     /* hash */ resourceLoader.bootConfig.resources.runtime[dotnetWasmResourceName]);
 
+  const dotnetTimeZoneResourceName = 'dotnet.timezones.dat';
+  let timeZoneResource: LoadingResource | undefined;
+  if (resourceLoader.bootConfig.resources.runtime.hasOwnProperty(dotnetTimeZoneResourceName)) {
+    timeZoneResource = resourceLoader.loadResource(
+      dotnetTimeZoneResourceName,
+      `_framework/wasm/${dotnetTimeZoneResourceName}`,
+      resourceLoader.bootConfig.resources.runtime[dotnetTimeZoneResourceName]);
+  }
+
   // Override the mechanism for fetching the main wasm file so we can connect it to our cache
   module.instantiateWasm = (imports, successCallback): WebAssembly.Exports => {
     (async () => {
@@ -206,6 +216,10 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
 
     MONO.loaded_files = [];
 
+    if (timeZoneResource) {
+      loadTimezone(timeZoneResource);
+    }
+
     // Fetch the assemblies and PDBs in the background, telling Mono to wait until they are loaded
     // Mono requires the assembly filenames to have a '.dll' extension, so supply such names regardless
     // of the extensions in the URLs. This allows loading assemblies with arbitrary filenames.
@@ -339,6 +353,17 @@ function attachInteropInvoker(): void {
   });
 }
 
+async function loadTimezone(timeZoneResource: LoadingResource) : Promise<void> {
+  const runDependencyId = `blazor:timezonedata`;
+  Module.addRunDependency(runDependencyId);
+
+  const request = await timeZoneResource.response;
+  const arrayBuffer = await request.arrayBuffer();
+  loadTimezoneData(arrayBuffer)
+
+  Module.removeRunDependency(runDependencyId);
+}
+
 async function compileWasmModule(wasmResource: LoadingResource, imports: any): Promise<WebAssembly.Instance> {
   // This is the same logic as used in emscripten's generated js. We can't use emscripten's js because
   // it doesn't provide any method for supplying a custom response provider, and we want to integrate

src/Components/Web.JS/src/Platform/Mono/TimezoneDataFile.ts

@@ -0,0 +1,44 @@
+import { readInt32LE } from "../../BinaryDecoder";
+import { decodeUtf8 } from "../../Utf8Decoder";
+
+export async function loadTimezoneData(arrayBuffer: ArrayBuffer) : Promise<void> {
+    let remainingData = new Uint8Array(arrayBuffer);
+
+    // The timezone file is generated by https://github.com/dotnet/blazor/tree/master/src/TimeZoneData.
+    // The file format of the TZ file look like so
+    //
+    // [4 - byte length of manifest]
+    // [json manifest]
+    // [data bytes]
+    //
+    // The json manifest is an array that looks like so:
+    //
+    // [...["America/Fort_Nelson",2249],["America/Glace_Bay",2206]..]
+    //
+    // where the first token in each array is the relative path of the file on disk, and the second is the
+    // length of the file. The starting offset of a file can be calculated using the lengths of all files
+    // that appear prior to it.
+    const manifestSize = readInt32LE(remainingData, 0);
+    remainingData = remainingData.slice(4);
+    const manifestContent = decodeUtf8(remainingData.slice(0, manifestSize));
+    const manifest = JSON.parse(manifestContent) as ManifestEntry[];
+    remainingData = remainingData.slice(manifestSize);
+
+    // Create the folder structure
+    // /zoneinfo
+    // /zoneinfo/Africa
+    // /zoneinfo/Asia
+    // ..
+    Module['FS_createPath']('/', 'zoneinfo', true, true);
+    new Set(manifest.map(m => m[0].split('/')![0])).forEach(folder =>
+      Module['FS_createPath']('/zoneinfo', folder, true, true));
+
+    for (const [name, length] of manifest) {
+      const bytes = new Uint8Array(remainingData.slice(0, length));
+      Module['FS_createDataFile'](`/zoneinfo/${name}`, null, bytes, true, true, true);
+      remainingData = remainingData.slice(length);
+    }
+
+  }
+
+  type ManifestEntry = [string, number];

src/Components/Web.JS/src/Rendering/RenderBatch/OutOfProcessRenderBatch.ts

@@ -1,5 +1,6 @@
 import { RenderBatch, ArrayRange, RenderTreeDiff, ArrayValues, RenderTreeEdit, EditType, FrameType, RenderTreeFrame, RenderTreeDiffReader, RenderTreeFrameReader, RenderTreeEditReader, ArrayRangeReader, ArrayBuilderSegmentReader, ArrayBuilderSegment } from './RenderBatch';
-import { decodeUtf8 } from './Utf8Decoder';
+import { decodeUtf8 } from '../../Utf8Decoder';
+import { readInt32LE, readUint64LE, readLEB128, numLEB128Bytes } from '../../BinaryDecoder';
 
 const updatedComponentsEntryLength = 4; // Each is a single int32 giving the location of the data
 const referenceFramesEntryLength = 20; // 1 int for frame type, then 16 bytes for type-specific data
@@ -7,8 +8,6 @@ const disposedComponentIdsEntryLength = 4; // Each is an int32 giving the ID
 const disposedEventHandlerIdsEntryLength = 8; // Each is an int64 giving the ID
 const editsEntryLength = 16; // 4 ints
 const stringTableEntryLength = 4; // Each is an int32 giving the string data location, or -1 for null
-const uint64HighPartShift = Math.pow(2, 32);
-const maxSafeNumberHighPart = Math.pow(2, 21) - 1; // The high-order int32 from Number.MAX_SAFE_INTEGER
 
 export class OutOfProcessRenderBatch implements RenderBatch {
   constructor(private batchData: Uint8Array) {
@@ -230,47 +229,4 @@ class OutOfProcessArrayBuilderSegmentReader implements ArrayBuilderSegmentReader
   }
 }
 
-function readInt32LE(buffer: Uint8Array, position: number): any {
-  return (buffer[position])
-    | (buffer[position + 1] << 8)
-    | (buffer[position + 2] << 16)
-    | (buffer[position + 3] << 24);
-}
 
-function readUint32LE(buffer: Uint8Array, position: number): any {
-  return (buffer[position])
-    + (buffer[position + 1] << 8)
-    + (buffer[position + 2] << 16)
-    + ((buffer[position + 3] << 24) >>> 0); // The >>> 0 coerces the value to unsigned
-}
-
-function readUint64LE(buffer: Uint8Array, position: number): any {
-  // This cannot be done using bit-shift operators in JavaScript, because
-  // those all implicitly convert to int32
-  const highPart = readUint32LE(buffer, position + 4);
-  if (highPart > maxSafeNumberHighPart) {
-    throw new Error(`Cannot read uint64 with high order part ${highPart}, because the result would exceed Number.MAX_SAFE_INTEGER.`);
-  }
-
-  return (highPart * uint64HighPartShift) + readUint32LE(buffer, position);
-}
-
-function readLEB128(buffer: Uint8Array, position: number) {
-  let result = 0;
-  let shift = 0;
-  for (let index = 0; index < 4; index++) {
-    const byte = buffer[position + index];
-    result |= (byte & 127) << shift;
-    if (byte < 128) {
-      break;
-    }
-    shift += 7;
-  }
-  return result;
-}
-
-function numLEB128Bytes(value: number) {
-  return value < 128 ? 1
-    : value < 16384 ? 2
-      : value < 2097152 ? 3 : 4;
-}

src/Components/WebAssembly/Build/src/targets/Blazor.MonoRuntime.targets

@@ -82,7 +82,11 @@
     <ItemGroup>
       <_BlazorJSFile Include="$(_BlazorJSPath)" />
       <_BlazorJSFile Include="$(_BlazorJSMapPath)" Condition="Exists('$(_BlazorJSMapPath)')" />
-      <_DotNetWasmRuntimeFile Include="$(ComponentsWebAssemblyRuntimePath)*" />
+
+      <_DotNetWasmRuntimeFile Include="$(ComponentsWebAssemblyRuntimePath)*"/>
+      <_DotNetWasmRuntimeFile
+        Remove="%(Identity)"
+        Condition="'$(BlazorEnableTimeZoneSupport)' == 'false' AND '%(FileName)%(Extension)' == 'dotnet.timezones.dat'" />
 
       <!--
         ReferenceCopyLocalPaths includes all files that are part of the build out with CopyLocalLockFileAssemblies on.

src/Components/WebAssembly/Build/src/targets/Standalone.Web.config

@@ -2,12 +2,14 @@
 <configuration>
   <system.webServer>
     <staticContent>
+      <remove fileExtension=".dat" />
       <remove fileExtension=".dll" />
       <remove fileExtension=".json" />
       <remove fileExtension=".wasm" />
       <remove fileExtension=".woff" />
       <remove fileExtension=".woff2" />
       <mimeMap fileExtension=".dll" mimeType="application/octet-stream" />
+      <mimeMap fileExtension=".dat" mimeType="application/octet-stream" />
       <mimeMap fileExtension=".json" mimeType="application/json" />
       <mimeMap fileExtension=".wasm" mimeType="application/wasm" />
       <mimeMap fileExtension=".woff" mimeType="application/font-woff" />

src/Components/WebAssembly/Build/test/BuildIntegrationTests/BuildCompressionTests.cs

@@ -81,7 +81,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
 
             var buildOutputDirectory = project.BuildOutputDirectory;
 
-            var extensions = new[] { ".dll", ".js", ".pdb", ".wasm", ".map", ".json" };
+            var extensions = new[] { ".dll", ".js", ".pdb", ".wasm", ".map", ".json", ".dat" };
             // Act
             var compressedFilesPath = Path.Combine(
                 project.DirectoryPath,
@@ -218,7 +218,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
 
             var buildOutputDirectory = project.BuildOutputDirectory;
 
-            var extensions = new[] { ".dll", ".js", ".pdb", ".wasm", ".map", ".json" };
+            var extensions = new[] { ".dll", ".js", ".pdb", ".wasm", ".map", ".json", ".dat" };
             // Act
             var compressedFilesPath = Path.Combine(
                 project.DirectoryPath,

src/Components/WebAssembly/Build/test/BuildIntegrationTests/BuildIntegrationTest.cs

@@ -27,6 +27,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "blazor.webassembly.js");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.wasm");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", DotNetJsFileName);
+            Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.timezones.dat");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "standalone.dll");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "RazorClassLibrary.dll");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "Microsoft.Extensions.Logging.Abstractions.dll"); // Verify dependencies are part of the output.
@@ -53,6 +54,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "blazor.webassembly.js");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.wasm");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", DotNetJsFileName);
+            Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.timezones.dat");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "standalone.dll");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "RazorClassLibrary.dll");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "Microsoft.Extensions.Logging.Abstractions.dll"); // Verify dependencies are part of the output.
@@ -81,6 +83,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             var runtime = bootJsonData.resources.runtime.Keys;
             Assert.Contains(DotNetJsFileName, runtime);
             Assert.Contains("dotnet.wasm", runtime);
+            Assert.Contains("dotnet.timezones.dat", runtime);
 
             var assemblies = bootJsonData.resources.assembly.Keys;
             Assert.Contains("standalone.dll", assemblies);
@@ -112,6 +115,7 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             var runtime = bootJsonData.resources.runtime.Keys;
             Assert.Contains(DotNetJsFileName, runtime);
             Assert.Contains("dotnet.wasm", runtime);
+            Assert.Contains("dotnet.timezones.dat", runtime);
 
             var assemblies = bootJsonData.resources.assembly.Keys;
             Assert.Contains("standalone.dll", assemblies);
@@ -122,6 +126,35 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             Assert.Null(bootJsonData.resources.satelliteResources);
         }
 
+        [Fact]
+        public async Task Build_WithBlazorEnableTimeZoneSupportDisabled_DoesNotCopyTimeZoneInfo()
+        {
+            // Arrange
+            using var project = ProjectDirectory.Create("standalone", additionalProjects: new[] { "razorclasslibrary" });
+            project.Configuration = "Release";
+            project.AddProjectFileContent(
+@"
+<PropertyGroup>
+    <BlazorEnableTimeZoneSupport>false</BlazorEnableTimeZoneSupport>
+</PropertyGroup>");
+
+            var result = await MSBuildProcessManager.DotnetMSBuild(project);
+
+            Assert.BuildPassed(result);
+
+            var buildOutputDirectory = project.BuildOutputDirectory;
+
+            var bootJsonPath = Path.Combine(buildOutputDirectory, "wwwroot", "_framework", "blazor.boot.json");
+            var bootJsonData = ReadBootJsonData(result, bootJsonPath);
+
+            var runtime = bootJsonData.resources.runtime.Keys;
+            Assert.Contains("dotnet.wasm", runtime);
+            Assert.DoesNotContain("dotnet.timezones.dat", runtime);
+
+            Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.wasm");
+            Assert.FileDoesNotExist(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.timezones.dat");
+        }
+
         [Fact]
         public async Task Build_Hosted_Works()
         {
@@ -163,6 +196,8 @@ namespace Microsoft.AspNetCore.Components.WebAssembly.Build
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "blazor.webassembly.js");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.wasm");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", DotNetJsFileName);
+            Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "wasm", "dotnet.timezones.dat");
+
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "standalone.dll");
             Assert.FileExists(result, buildOutputDirectory, "wwwroot", "_framework", "_bin", "Microsoft.Extensions.Logging.Abstractions.dll"); // Verify dependencies are part of the output.
         }

src/Components/WebAssembly/Server/src/ComponentsWebAssemblyApplicationBuilderExtensions.cs

@@ -76,6 +76,7 @@ namespace Microsoft.AspNetCore.Builder
             // release builds unless BlazorEnableDebugging is explicitly set to true.
             AddMapping(contentTypeProvider, ".pdb", MediaTypeNames.Application.Octet);
             AddMapping(contentTypeProvider, ".br", MediaTypeNames.Application.Octet);
+            AddMapping(contentTypeProvider, ".dat", MediaTypeNames.Application.Octet);
 
             options.ContentTypeProvider = contentTypeProvider;
 

src/Components/test/E2ETest/ServerExecutionTests/ServerGlobalizationTest.cs

@@ -26,8 +26,6 @@ namespace Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests
         {
         }
 
-        protected override TimeSpan UtcOffset => TimeZoneInfo.Local.BaseUtcOffset;
-
         protected override void InitializeAsyncCore()
         {
             Navigate(ServerPathBase);

src/Components/test/E2ETest/Tests/GlobalizationTest.cs

@@ -22,13 +22,6 @@ namespace Microsoft.AspNetCore.Components.E2ETests.Tests
 
         protected abstract void SetCulture(string culture);
 
-        /// <summary>
-        /// Blazor Server and these tests will use the application's UtcOffset when calculating DateTimeOffset when
-        /// an offset is not explicitly specified. Blazor WASM always calculates DateTimeOffsets as Utc.
-        /// We'll use <see cref="UtcOffset"/> to express this difference in calculating expected values in these tests.
-        /// </summary>
-        protected abstract TimeSpan UtcOffset { get; }
-
         [Theory]
         [InlineData("en-US")]
         [InlineData("fr-FR")]
@@ -69,11 +62,11 @@ namespace Microsoft.AspNetCore.Components.E2ETests.Tests
             // datetimeoffset
             input = Browser.FindElement(By.Id("input_type_text_datetimeoffset"));
             display = Browser.FindElement(By.Id("input_type_text_datetimeoffset_value"));
-            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4), UtcOffset).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4)).ToString(cultureInfo), () => display.Text);
 
-            input.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo));
+            input.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo));
             input.SendKeys("\t");
-            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo), () => display.Text);
         }
 
         // The logic is different for verifying culture-invariant fields. The problem is that the logic for what
@@ -140,13 +133,13 @@ namespace Microsoft.AspNetCore.Components.E2ETests.Tests
             input = Browser.FindElement(By.Id("input_type_date_datetimeoffset"));
             display = Browser.FindElement(By.Id("input_type_date_datetimeoffset_value"));
             extraInput = Browser.FindElement(By.Id("input_type_date_datetimeoffset_extrainput"));
-            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4), UtcOffset).ToString(cultureInfo), () => display.Text);
-            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4), UtcOffset).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
+            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4)).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4)).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
 
-            extraInput.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo));
+            extraInput.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo));
             extraInput.SendKeys("\t");
-            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo), () => display.Text);
-            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
+            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
         }
 
         [Theory]
@@ -209,13 +202,13 @@ namespace Microsoft.AspNetCore.Components.E2ETests.Tests
             input = Browser.FindElement(By.Id("inputdate_datetimeoffset"));
             display = Browser.FindElement(By.Id("inputdate_datetimeoffset_value"));
             extraInput = Browser.FindElement(By.Id("inputdate_datetimeoffset_extrainput"));
-            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4), UtcOffset).ToString(cultureInfo), () => display.Text);
-            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4), UtcOffset).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
+            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4)).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(1985, 3, 4)).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
 
-            extraInput.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo));
+            extraInput.ReplaceText(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo));
             extraInput.SendKeys("\t");
-            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString(cultureInfo), () => display.Text);
-            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2), UtcOffset).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
+            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString(cultureInfo), () => display.Text);
+            Browser.Equal(new DateTimeOffset(new DateTime(2000, 1, 2)).ToString("yyyy-MM-dd", CultureInfo.InvariantCulture), () => input.GetAttribute("value"));
         }
     }
 }

src/Components/test/E2ETest/Tests/WebAssemblyGlobalizationTest.cs

@@ -24,8 +24,6 @@ namespace Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests
         {
         }
 
-        protected override TimeSpan UtcOffset => TimeSpan.Zero;
-
         protected override void SetCulture(string culture)
         {
             Navigate($"{ServerPathBase}/?culture={culture}", noReload: false);