pkg/test_runner/lib/src/browser.dart - sdk - Git at Google

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 import 'package:path/path.dart' as p;

 import 'configuration.dart' show Compiler;
 import 'utils.dart';

 // The native JavaScript Object prototype is sealed before loading the Dart
 // SDK module to guard against prototype pollution.
 final _sealNativeObjectScript =
     '/root_dart/sdk/lib/_internal/js_runtime/lib/preambles/'
     'seal_native_object.js';

 String dart2jsHtml(String title, String scriptPath) {
   return """
 <!DOCTYPE html>
 <html>
 <head>
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta charset="utf-8">
   <meta name="dart.unittest" content="full-stack-traces">
   <title> Test $title </title>
   <style>
      .unittest-table { font-family:monospace; border:1px; }
      .unittest-pass { background: #6b3;}
      .unittest-fail { background: #d55;}
      .unittest-error { background: #a11;}
   </style>
   <script type="text/javascript" src="$_sealNativeObjectScript"></script>
 </head>
 <body>
   <h1> Running $title </h1>
   <script type="text/javascript"
           src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
   </script>
   <script type="text/javascript" src="$scriptPath"
           onerror="scriptTagOnErrorCallback(null)"
           defer>
   </script>
 </body>
 </html>""";
 }

 /// Transforms a path to a valid JS identifier.
 ///
 /// This logic must be synchronized with [pathToJSIdentifier] in DDC at:
 /// pkg/dev_compiler/lib/src/compiler/module_builder.dart
 String pathToJSIdentifier(String path) {
   path = p.normalize(path);
   if (path.startsWith('/') || path.startsWith('\\')) {
     path = path.substring(1, path.length);
   }
   return _toJSIdentifier(
     path
         .replaceAll('\\', '__')
         .replaceAll('/', '__')
         .replaceAll('..', '__')
         .replaceAll('-', '_'),
   );
 }

 final _digitPattern = RegExp(r'\d');

 /// Escape [name] to make it into a valid identifier.
 String _toJSIdentifier(String name) {
   if (name.isEmpty) return r'$';

   // Escape any invalid characters
   var result = name.replaceAllMapped(
     _invalidCharInIdentifier,
     (match) => '\$${match[0]!.codeUnits.join("")}',
   );

   // Ensure the identifier first character is not numeric and that the whole
   // identifier is not a keyword.
   if (result.startsWith(_digitPattern) || _invalidVariableName(result)) {
     return '\$$result';
   }
   return result;
 }

 // Invalid characters for identifiers, which would need to be escaped.
 final _invalidCharInIdentifier = RegExp(r'[^A-Za-z_\d]');

 bool _invalidVariableName(String keyword, {bool strictMode = true}) {
   switch (keyword) {
     // http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words
     case "await":
     case "break":
     case "case":
     case "catch":
     case "class":
     case "const":
     case "continue":
     case "debugger":
     case "default":
     case "delete":
     case "do":
     case "else":
     case "enum":
     case "export":
     case "extends":
     case "finally":
     case "for":
     case "function":
     case "if":
     case "import":
     case "in":
     case "instanceof":
     case "let":
     case "new":
     case "return":
     case "super":
     case "switch":
     case "this":
     case "throw":
     case "try":
     case "typeof":
     case "var":
     case "void":
     case "while":
     case "with":
       return true;
     case "arguments":
     case "eval":
     // http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words
     // http://www.ecma-international.org/ecma-262/6.0/#sec-identifiers-static-semantics-early-errors
     case "implements":
     case "interface":
     case "package":
     case "private":
     case "protected":
     case "public":
     case "static":
     case "yield":
       return strictMode;
   }
   return false;
 }

 /// Generates the HTML template file needed to load and run a ddc test in
 /// the browser.
 ///
 /// [testName] is the short name of the test without any subdirectory path
 /// or extension, like "math_test". [testNameAlias] is the alias of the
 /// test variable used for import/export (usually relative to its module root).
 /// [testJSDir] is the relative path to the build directory where the
 /// ddc-generated JS file is stored. [ddcModuleFormat] determines whether to
 /// emit a template that works with the DDC module format or one that works with
 /// the AMD module format. [canaryMode] is whether DDC is running in canary
 /// mode. If this flag and [ddcModuleFormat] is enabled, a template that works
 /// with the DDC hot reload format will be emitted.
 String ddcHtml(
   String testName,
   String testNameAlias,
   String testJSDir,
   Compiler compiler,
   String genDir,
   bool nativeNonNullAsserts,
   bool jsInteropNonNullAsserts, {
   bool ddcModuleFormat = false,
   bool canaryMode = false,
 }) {
   var testId = pathToJSIdentifier(testName);
   var testIdAlias = pathToJSIdentifier(testNameAlias);
   var ddcGenDir = '/root_build/$genDir';
   var hotReloadFormat = ddcModuleFormat && canaryMode;

   var sdkAndAsyncHelperSetup = """
 _debugger.registerDevtoolsFormatter();

 testErrorToStackTrace = function(error) {
   var stackTrace = getStackTraceString(error);

   var lines = stackTrace.split("\\n");

   // Remove the first line, which is just "Error".
   lines = lines.slice(1);

   // Strip off all of the lines for the bowels of the test runner.
   for (var i = 0; i < lines.length; i++) {
     if (lines[i].indexOf("dartMainRunner") != -1) {
       lines = lines.slice(0, i);
       break;
     }
   }

   // TODO(rnystrom): It would be nice to shorten the URLs of the remaining
   // lines too.
   return lines.join("\\n");
 };
 """;

   var sdkFlagSetup =
       """
 runtime.nativeNonNullAsserts($nativeNonNullAsserts);
 runtime.jsInteropNonNullAsserts($jsInteropNonNullAsserts);
 """;

   String script;
   if (ddcModuleFormat) {
     var appName = '/root_dart/$testJSDir';
     // Used in the DDC module system for multi-app workflows, and are simply
     // placeholder values here.
     var uuid = '00000000-0000-0000-0000-000000000000';
     var loadPackagesScript = [
       for (var p in testPackages)
         """<script defer type="text/javascript"
                 src="$ddcGenDir/pkg/ddc/$p.js"></script>""",
     ].join('\n');
     String libraryImports;
     String startCode;
     if (hotReloadFormat) {
       libraryImports = """
         let _debugger = dartDevEmbedder.debugger;
         let getStackTraceString = function(error) {
           return _debugger.stackTrace(error);
         }
       """;
       sdkFlagSetup =
           """
         let sdkOptions = {
           nativeNonNullAsserts: $nativeNonNullAsserts,
           jsInteropNonNullAsserts: $jsInteropNonNullAsserts,
         };
       """;
       startCode =
           """dartDevEmbedder.runMain("org-dartlang-app:/$testNameAlias.dart",
           sdkOptions);""";
     } else {
       libraryImports =
           """
         let sdk = dart_library.import("dart_sdk", "$appName");
         let runtime = sdk.dart;
         let getStackTraceString = function(error) {
           return runtime.stackTrace(error).toString();
         }
         let _debugger = sdk._debugger;
       """;
       startCode = """dart_library.start("$appName", "$uuid", "$testName",
           "$testIdAlias", false)""";
     }
     script =
         """
 <script defer type="text/javascript"
 src="/root_dart/pkg/dev_compiler/lib/js/ddc/ddc_module_loader.js"></script>
 <script defer type="text/javascript" src="$ddcGenDir/sdk/ddc/dart_sdk.js"></script>
 $loadPackagesScript
 <script defer type="text/javascript" src="$appName/$testName.js"></script>
 <script type="text/javascript">"""
         // DDC module format doesn't defer the execution until the document is finished
         // parsing. We can defer scripts, but only if they are in separate files and not
         // inline JS like below. In order to make sure everything is loaded and be
         // consistent with the AMD module format, we should wait until a
         // `DOMContentLoaded` event is fired. Other options are using `type = "module"`
         // or putting this in a separate JS file, but this is the simplest solution.
         """
 document.addEventListener("DOMContentLoaded", (e) => {
   $libraryImports
   $sdkAndAsyncHelperSetup
   $sdkFlagSetup

   dartMainRunner(function () {
     return $startCode;
   });
 });
 </script>
     """;
   } else {
     var packagePaths = [
       for (var p in testPackages) '    "$p": "$ddcGenDir/pkg/amd/$p",',
     ].join("\n");
     script =
         """
 <script>
 var require = {
   baseUrl: "/root_dart/$testJSDir",
   paths: {
     "dart_sdk": "$ddcGenDir/sdk/amd/dart_sdk",
 $packagePaths
   },
   waitSeconds: 45,
 };
 </script>
 <script type="text/javascript"
         src="/root_dart/third_party/requirejs/require.js"></script>
 <script type="text/javascript">
 requirejs(["$testName", "dart_sdk"], function($testId, sdk) {
   let runtime = sdk.dart;
   let getStackTraceString = function(error) {
     return runtime.stackTrace(error).toString();
   }
   let _debugger = sdk._debugger;

   $sdkAndAsyncHelperSetup
   $sdkFlagSetup

   dartMainRunner(function testMainWrapper() {
     return $testId.$testIdAlias.main();
   });
 });
 </script>
     """;
   }
   return """
 <!DOCTYPE html>
 <html>
 <head>
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta charset="utf-8">
   <meta name="dart.unittest" content="full-stack-traces">
   <title>Test $testName</title>
   <style>
      .unittest-table { font-family:monospace; border:1px; }
      .unittest-pass { background: #6b3;}
      .unittest-fail { background: #d55;}
      .unittest-error { background: #a11;}
   </style>
   <script type="text/javascript" src="$_sealNativeObjectScript"></script>
 </head>
 <body>
 <h1>Running $testName</h1>
 <script type="text/javascript"
         src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
 </script>
 $script
 </body>
 </html>
 """;
 }

 /*
 Helper function to turn WebAssembly arrays into strings (which isn't possible
 with JavaScript alone). Generated from this WAT module via `wasm-as -all`
 and `base64 -w 0`:

 (module
   (type $i8array (array (mut i8)))
   (type $i16array (array (mut i16)))
   (import "wasm:js-string" "fromCharCodeArray"
     (func $fromCharCodeArray (param (ref null $i16array) i32 i32) (result (ref extern)))
   )

   (func (export "stringFromAsciiBytes")
     (param $arr (ref $i8array))
     (param $start i32)
     (param $length i32)
     (result (ref extern))

     (local $i i32)
     (local $expanded (ref $i16array))

     ;; Copy i8 array into an i16 array
     (local.set $i (local.get $length))
     (local.set $expanded (array.new $i16array (i32.const 0) (local.get $length)))

     ;; do { i--; expanded[i] = arr[i]; } while (i >= start);
     (block $break
       (loop $loop
         (local.set $i (i32.add (local.get $i) (i32.const -1)))
         (br_if $break
           (i32.lt_s
             (local.get $i)
             (local.get $start)
           )
         )

         (array.set $i16array
           (local.get $expanded)
             (local.get $i)
             (array.get_u $i8array (local.get $arr) (local.get $i))
           )
           br $loop
       )
     )

     (call $fromCharCodeArray
       (local.get $expanded)
       (i32.const 0)
       (array.len (local.get $expanded))
     )
   )

   (func (export "stringFromCharCodeArray")
     (param $arr (ref $i16array))
     (param $start i32)
     (param $length i32)
     (result (ref extern))

     (call $fromCharCodeArray
       (local.get $arr)
       (local.get $start)
       (i32.add
         (local.get $start)
         (local.get $length)
       )
     )
   )
 )
  */
 const _wasmStandaloneArrayHelper =
     'AGFzbQEAAAABIgVedwFeeAFgA2MAf38BZG9gA2QBf38BZG9gA2QAf38BZG8CJAEOd2FzbTpqcy1zdHJpbmcRZnJvbUNoYXJDb2RlQXJyYXkAAgMDAgMEBzICFHN0cmluZ0Zyb21Bc2NpaUJ5dGVzAAEXc3RyaW5nRnJvbUNoYXJDb2RlQXJyYXkAAgpTAkMCAX8BZAAgAiEDQQAgAvsGACEEAkADQCADQX9qIQMgAyABSA0BIAQgAyAAIAP7DQH7DgAMAAsACyAEQQAgBPsPEAALDQAgACABIAEgAmoQAAs=';

 String dart2wasmHtml(
   String title,
   String wasmPath,
   String mjsPath,
   String supportJsPath,
   bool standalone,
 ) {
   const standaloneEmbedder =
       """
     const { instance: helperInstance } = await WebAssembly.instantiate(Uint8Array.fromBase64('$_wasmStandaloneArrayHelper'), {}, {
       builtins: ['js-string']
     });

     const dartEmbedder = {
       // See sdk/lib/_internal/wasm_standalone/lib/embedder.dart for required definitions.
       scheduleOnce: (delayInMicros, callback, arg) => {
         const timeout = setTimeout(() => callback(arg), Number(delayInMicros / 1000n));
         return {timeout};
       },
       scheduleRepeated: (intervalMicros, callback, arg) => {
         const timeout = setInterval(() => callback(arg), Number(intervalMicros / 1000n));
         return {timeout};
       },
       queueMicrotask: (callback, arg) => {
         queueMicrotask(() => callback(arg));
       },
       clearSchedule: (schedule) => {
         clearTimeout(schedule.timeout);
       },
       currentTime: () => BigInt(Date.now()) * 1000n,
       stringFromAsciiBytes: (chars, start, length) => {
         const str = helperInstance.exports.stringFromAsciiBytes(chars, start, length);
         return str;
       },
       stringFromCharCodeArray: (chars, start, length) => {
         const str = helperInstance.exports.stringFromCharCodeArray(chars, start, length);
         return str;
       },
       monotonicClockFrequency: () => 1_000_000,
       monotonicClockTicks: () => BigInt(Math.round(performance.now() * 1000)),
       weakRefCreate: (dartValue) => new WeakRef(dartValue),
       weakRefGet: (weakRef) => weakRef.deref() ?? null,
       expandoCreate: () => new WeakMap(),
       expandoGet: (expando, target, _hash) => expando.get(target) ?? null,
       expandoSet: (expando, target, _hash, value) => expando.set(target, value),
       finalizerCreate: (callback, firstParameter) => {
         return new FinalizationRegistry((heldValue) => {
           callback(heldValue, firstParameter);
         });
       },
       finalizerAttach: (finalizer, object, token, detachToken) => {
         if (detachToken) {
           finalizer.register(object, token, detachToken);
         } else {
           finalizer.register(object, token);
         }
       },
       finalizerDetach: (finalizer, detachToken) => finalizer.unregister(detachToken),
       baseUri: () => globalThis.location.href,
       isWindows: () => false,
       stackTraceGetCurrent: () => new Error().stack,
       stackTraceToString: (trace) => {
         const stackString = trace.toString();
         const frames = stackString.split('\\n');
         // Format of stack traces is:
         //   1. stackTraceGetCurrent (from this embedder object)
         //   2. module0.StackTrace.current <noInline>
         //   3. The callsite we care about.
         const drop = 1 + frames.findIndex((l) => l.indexOf('stackTraceGetCurrent') > 0);
         return frames.slice(drop).join('\\n');
       },
       doubleTryParse: (source) => {
         if (!/${r'^\s*[+-]?(?:Infinity|NaN|(?:\.\d+|\d+(?:\.\d*)?)(?:[eE][+-]?\d+)?)\s*$'}/.test(source)) {
           const trimmed = source.trim();
           // parseFloat is more lenient than double.tryParse, see wasm/lib/double_patch.dart for details.
           if (!(trimmed == 'NaN' || trimmed == '+NaN' || trimmed == '-NaN')) {
             return null;
           }
           return { result: NaN };
         } else {
           return { result: parseFloat(source) };
         }
       },
       tryParseResultGetDouble: ({result}) => result,
       i64ToString: (source, radix) => source.toString(radix),
       f64ToExponential: (source) => source.toExponential(),
       f64ToExponentialWithFractionDigits: (source, digits) => {
         return source.toExponential(digits);
       },
       f64ToPrecision: (source, digits) => source.toPrecision(digits),
       f64ToFixed: (source, digits) => source.toFixed(digits),
       f64ToString: (source) => {
         if (Object.is(source, -0)) return '-0.0';
         if (Number.isNaN(source)) return 'NaN';
         if (source == Number.NEGATIVE_INFINITY) return '-Infinity';
         if (source == Number.POSITIVE_INFINITY) return 'Infinity';

         let formatted = source.toString();
         if (source % 1.0 == 0 && formatted.indexOf('e') == -1) {
           formatted += '.0';
         }
         return formatted;
       },
       stringBufferCreate: () => ({ contents: '' }),
       stringBufferWriteString: (buffer, append) => {
         buffer.contents += append;
       },
       stringBufferWriteCharCode: (buffer, code) => {
         buffer.contents += String.fromCodePoint(code);
       },
       stringBufferClear: (buffer) => {
         buffer.contents = ''
       },
       stringBufferLength: (buffer) => buffer.contents.length,
       stringBufferToString: ({contents}) => contents,
       regexpCreateOrFailWithString: (pattern, multiLine, caseSensitive, unicode, dotAll) => {
         let flags = '';
         if (multiLine) flags += 'm';
         if (!caseSensitive) flags += 'i';
         if (unicode) flags += 'u';
         if (dotAll) flags += 's';

         try {
           // Prepare two regular expressions, one for regular matches and one
           // for matchAsPrefix.
           return {
             regular: new RegExp(pattern, flags + 'g'),
             asPrefix: new RegExp(pattern, flags + 'y'),
           };
         } catch (e) {
           return String(e);
         }
       },
       regexpIsRegexp: (source) => typeof(source) !== 'string',
       regexpEscape: (source) => {
         // Note: We can't use RegExp.escape here, it escapes too much and we
         // have tests expecting that e.g. \t isn't escaped.
         if (/${r'[[\]{}()*+?.\\^$|]'}/.test(source)) {
           return source.replace(/${r'[[\]{}()*+?.\\^$|]'}/g, "${r'\\$&'}");
         } else {
           return source;
         }
       },
       regexpMatch: (regexp, string, start, asPrefix) => {
         const regex = asPrefix ? regexp.asPrefix : regexp.regular;
         regex.lastIndex = start;
         const match = regex.exec(string);
         if (match) {
           return {
             start: match.index,
             end: match.index + match[0].length,
             groupNames: match.groups ? Object.keys(match.groups) : [],
             groups: match,
           };
         } else {
           return null;
         }
       },
       regexpMatchGetStart: (match) => match.start,
       regexpMatchGetEnd: (match) => match.end,
       regexpMatchGetGroupCount: (match) => match.groups.length - 1,
       regexpMatchGetGroup: (match, index) => match.groups[index] ?? null,
       regexpMatchGetNamedGroups: (match) => match.groupNames.length,
       regexpMatchGetGroupName: (match, index) => match.groupNames[index],
       regexpMatchGetGroupByName: (match, index) => match.groups.groups[match.groupNames[index]] ?? null,
       timeZoneNameForClampedSeconds: (secondsSinceEpoch) => {
         const date = new Date(Number(secondsSinceEpoch * 1000n));
         const match = /\\((.*)\\)/.exec(date.toString());
         if (match == null) {
             // This should never happen on any recent browser.
             return '';
         }
         return match[1];
       },
       timeZoneOffsetInSecondsForClampedSeconds: (secondsSinceEpoch) => {
         const date = new Date(Number(secondsSinceEpoch * 1000n));
         // This needs to be negated because Dart wants the difference between
         // local time and UTC.
         return -date.getTimezoneOffset() * 60;
       },
     };
 """;
   final additionalImports = standalone ? '{ dart: dartEmbedder }' : '{}';

   return """
 <!DOCTYPE html>
 <html>
 <head>
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta charset="utf-8">
   <meta name="dart.unittest" content="full-stack-traces">
   <title> Test $title </title>
   <link rel="preload" href="$wasmPath" as="fetch" crossorigin>
   <style>
      .unittest-table { font-family:monospace; border:1px; }
      .unittest-pass { background: #6b3;}
      .unittest-fail { background: #d55;}
      .unittest-error { background: #a11;}
   </style>
 </head>
 <body>
   <h1> Running $title </h1>
   <script type="text/javascript"
           src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
   </script>
   <script type="module">
   // Default stack trace limit in V8 is 10, which hides some of the stack frames
   // we check in stack trace tests.
   Error.stackTraceLimit = 20;
   async function loadAndRun(mjsPath, wasmPath, supportJsPath) {
     const supportJSExpression = await (await fetch(supportJsPath)).text();
     const support = eval(supportJSExpression);
     if (support !== true) {
       dartMainRunner(() => {
         throw 'This browser does not support the required features to run the dart2wasm compiled app!';
       });
       return;
     }

     const mjs = await import(mjsPath);
     const compiledApp = await mjs.compileStreaming(fetch(wasmPath));
     window.loadData = async (relativeToWasmFileUri) => {
       const path = '$wasmPath'.slice(0, wasmPath.lastIndexOf('/'));
       const response = await fetch(`\${path}/\${relativeToWasmFileUri}`);
       return response.arrayBuffer();
     };
 ${standalone ? standaloneEmbedder : ''}
     const appInstance = await compiledApp.instantiate($additionalImports, {
       loadDeferredModules: (modules, handleWasmBytes) =>
         Promise.all(modules.map((m) => fetch(m).then((b) => handleWasmBytes(m, b)))),
     });
     dartMainRunner(() => {
       appInstance.invokeMain();
     });
   }

   loadAndRun('$mjsPath', '$wasmPath', '$supportJsPath');
   </script>
 </body>
 </html>""";
 }
	// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	import 'package:path/path.dart' as p;

	import 'configuration.dart' show Compiler;
	import 'utils.dart';

	// The native JavaScript Object prototype is sealed before loading the Dart
	// SDK module to guard against prototype pollution.
	final _sealNativeObjectScript =
	'/root_dart/sdk/lib/_internal/js_runtime/lib/preambles/'
	'seal_native_object.js';

	String dart2jsHtml(String title, String scriptPath) {
	return """
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta charset="utf-8">
	<meta name="dart.unittest" content="full-stack-traces">
	<title> Test $title </title>
	<style>
	.unittest-table { font-family:monospace; border:1px; }
	.unittest-pass { background: #6b3;}
	.unittest-fail { background: #d55;}
	.unittest-error { background: #a11;}
	</style>
	<script type="text/javascript" src="$_sealNativeObjectScript"></script>
	</head>
	<body>
	<h1> Running $title </h1>
	<script type="text/javascript"
	src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
	</script>
	<script type="text/javascript" src="$scriptPath"
	onerror="scriptTagOnErrorCallback(null)"
	defer>
	</script>
	</body>
	</html>""";
	}

	/// Transforms a path to a valid JS identifier.
	///
	/// This logic must be synchronized with [pathToJSIdentifier] in DDC at:
	/// pkg/dev_compiler/lib/src/compiler/module_builder.dart
	String pathToJSIdentifier(String path) {
	path = p.normalize(path);
	if (path.startsWith('/') \|\| path.startsWith('\\')) {
	path = path.substring(1, path.length);
	}
	return _toJSIdentifier(
	path
	.replaceAll('\\', '__')
	.replaceAll('/', '__')
	.replaceAll('..', '__')
	.replaceAll('-', '_'),
	);
	}

	final _digitPattern = RegExp(r'\d');

	/// Escape [name] to make it into a valid identifier.
	String _toJSIdentifier(String name) {
	if (name.isEmpty) return r'$';

	// Escape any invalid characters
	var result = name.replaceAllMapped(
	_invalidCharInIdentifier,
	(match) => '\$${match[0]!.codeUnits.join("")}',
	);

	// Ensure the identifier first character is not numeric and that the whole
	// identifier is not a keyword.
	if (result.startsWith(_digitPattern) \|\| _invalidVariableName(result)) {
	return '\$$result';
	}
	return result;
	}

	// Invalid characters for identifiers, which would need to be escaped.
	final _invalidCharInIdentifier = RegExp(r'[^A-Za-z_\d]');

	bool _invalidVariableName(String keyword, {bool strictMode = true}) {
	switch (keyword) {
	// http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words
	case "await":
	case "break":
	case "case":
	case "catch":
	case "class":
	case "const":
	case "continue":
	case "debugger":
	case "default":
	case "delete":
	case "do":
	case "else":
	case "enum":
	case "export":
	case "extends":
	case "finally":
	case "for":
	case "function":
	case "if":
	case "import":
	case "in":
	case "instanceof":
	case "let":
	case "new":
	case "return":
	case "super":
	case "switch":
	case "this":
	case "throw":
	case "try":
	case "typeof":
	case "var":
	case "void":
	case "while":
	case "with":
	return true;
	case "arguments":
	case "eval":
	// http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words
	// http://www.ecma-international.org/ecma-262/6.0/#sec-identifiers-static-semantics-early-errors
	case "implements":
	case "interface":
	case "package":
	case "private":
	case "protected":
	case "public":
	case "static":
	case "yield":
	return strictMode;
	}
	return false;
	}

	/// Generates the HTML template file needed to load and run a ddc test in
	/// the browser.
	///
	/// [testName] is the short name of the test without any subdirectory path
	/// or extension, like "math_test". [testNameAlias] is the alias of the
	/// test variable used for import/export (usually relative to its module root).
	/// [testJSDir] is the relative path to the build directory where the
	/// ddc-generated JS file is stored. [ddcModuleFormat] determines whether to
	/// emit a template that works with the DDC module format or one that works with
	/// the AMD module format. [canaryMode] is whether DDC is running in canary
	/// mode. If this flag and [ddcModuleFormat] is enabled, a template that works
	/// with the DDC hot reload format will be emitted.
	String ddcHtml(
	String testName,
	String testNameAlias,
	String testJSDir,
	Compiler compiler,
	String genDir,
	bool nativeNonNullAsserts,
	bool jsInteropNonNullAsserts, {
	bool ddcModuleFormat = false,
	bool canaryMode = false,
	}) {
	var testId = pathToJSIdentifier(testName);
	var testIdAlias = pathToJSIdentifier(testNameAlias);
	var ddcGenDir = '/root_build/$genDir';
	var hotReloadFormat = ddcModuleFormat && canaryMode;

	var sdkAndAsyncHelperSetup = """
	_debugger.registerDevtoolsFormatter();

	testErrorToStackTrace = function(error) {
	var stackTrace = getStackTraceString(error);

	var lines = stackTrace.split("\\n");

	// Remove the first line, which is just "Error".
	lines = lines.slice(1);

	// Strip off all of the lines for the bowels of the test runner.
	for (var i = 0; i < lines.length; i++) {
	if (lines[i].indexOf("dartMainRunner") != -1) {
	lines = lines.slice(0, i);
	break;
	}
	}

	// TODO(rnystrom): It would be nice to shorten the URLs of the remaining
	// lines too.
	return lines.join("\\n");
	};
	""";

	var sdkFlagSetup =
	"""
	runtime.nativeNonNullAsserts($nativeNonNullAsserts);
	runtime.jsInteropNonNullAsserts($jsInteropNonNullAsserts);
	""";

	String script;
	if (ddcModuleFormat) {
	var appName = '/root_dart/$testJSDir';
	// Used in the DDC module system for multi-app workflows, and are simply
	// placeholder values here.
	var uuid = '00000000-0000-0000-0000-000000000000';
	var loadPackagesScript = [
	for (var p in testPackages)
	"""<script defer type="text/javascript"
	src="$ddcGenDir/pkg/ddc/$p.js"></script>""",
	].join('\n');
	String libraryImports;
	String startCode;
	if (hotReloadFormat) {
	libraryImports = """
	let _debugger = dartDevEmbedder.debugger;
	let getStackTraceString = function(error) {
	return _debugger.stackTrace(error);
	}
	""";
	sdkFlagSetup =
	"""
	let sdkOptions = {
	nativeNonNullAsserts: $nativeNonNullAsserts,
	jsInteropNonNullAsserts: $jsInteropNonNullAsserts,
	};
	""";
	startCode =
	"""dartDevEmbedder.runMain("org-dartlang-app:/$testNameAlias.dart",
	sdkOptions);""";
	} else {
	libraryImports =
	"""
	let sdk = dart_library.import("dart_sdk", "$appName");
	let runtime = sdk.dart;
	let getStackTraceString = function(error) {
	return runtime.stackTrace(error).toString();
	}
	let _debugger = sdk._debugger;
	""";
	startCode = """dart_library.start("$appName", "$uuid", "$testName",
	"$testIdAlias", false)""";
	}
	script =
	"""
	<script defer type="text/javascript"
	src="/root_dart/pkg/dev_compiler/lib/js/ddc/ddc_module_loader.js"></script>
	<script defer type="text/javascript" src="$ddcGenDir/sdk/ddc/dart_sdk.js"></script>
	$loadPackagesScript
	<script defer type="text/javascript" src="$appName/$testName.js"></script>
	<script type="text/javascript">"""
	// DDC module format doesn't defer the execution until the document is finished
	// parsing. We can defer scripts, but only if they are in separate files and not
	// inline JS like below. In order to make sure everything is loaded and be
	// consistent with the AMD module format, we should wait until a
	// `DOMContentLoaded` event is fired. Other options are using `type = "module"`
	// or putting this in a separate JS file, but this is the simplest solution.
	"""
	document.addEventListener("DOMContentLoaded", (e) => {
	$libraryImports
	$sdkAndAsyncHelperSetup
	$sdkFlagSetup

	dartMainRunner(function () {
	return $startCode;
	});
	});
	</script>
	""";
	} else {
	var packagePaths = [
	for (var p in testPackages) ' "$p": "$ddcGenDir/pkg/amd/$p",',
	].join("\n");
	script =
	"""
	<script>
	var require = {
	baseUrl: "/root_dart/$testJSDir",
	paths: {
	"dart_sdk": "$ddcGenDir/sdk/amd/dart_sdk",
	$packagePaths
	},
	waitSeconds: 45,
	};
	</script>
	<script type="text/javascript"
	src="/root_dart/third_party/requirejs/require.js"></script>
	<script type="text/javascript">
	requirejs(["$testName", "dart_sdk"], function($testId, sdk) {
	let runtime = sdk.dart;
	let getStackTraceString = function(error) {
	return runtime.stackTrace(error).toString();
	}
	let _debugger = sdk._debugger;

	$sdkAndAsyncHelperSetup
	$sdkFlagSetup

	dartMainRunner(function testMainWrapper() {
	return $testId.$testIdAlias.main();
	});
	});
	</script>
	""";
	}
	return """
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta charset="utf-8">
	<meta name="dart.unittest" content="full-stack-traces">
	<title>Test $testName</title>
	<style>
	.unittest-table { font-family:monospace; border:1px; }
	.unittest-pass { background: #6b3;}
	.unittest-fail { background: #d55;}
	.unittest-error { background: #a11;}
	</style>
	<script type="text/javascript" src="$_sealNativeObjectScript"></script>
	</head>
	<body>
	<h1>Running $testName</h1>
	<script type="text/javascript"
	src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
	</script>
	$script
	</body>
	</html>
	""";
	}

	/*
	Helper function to turn WebAssembly arrays into strings (which isn't possible
	with JavaScript alone). Generated from this WAT module via `wasm-as -all`
	and `base64 -w 0`:

	(module
	(type $i8array (array (mut i8)))
	(type $i16array (array (mut i16)))
	(import "wasm:js-string" "fromCharCodeArray"
	(func $fromCharCodeArray (param (ref null $i16array) i32 i32) (result (ref extern)))
	)

	(func (export "stringFromAsciiBytes")
	(param $arr (ref $i8array))
	(param $start i32)
	(param $length i32)
	(result (ref extern))

	(local $i i32)
	(local $expanded (ref $i16array))

	;; Copy i8 array into an i16 array
	(local.set $i (local.get $length))
	(local.set $expanded (array.new $i16array (i32.const 0) (local.get $length)))

	;; do { i--; expanded[i] = arr[i]; } while (i >= start);
	(block $break
	(loop $loop
	(local.set $i (i32.add (local.get $i) (i32.const -1)))
	(br_if $break
	(i32.lt_s
	(local.get $i)
	(local.get $start)
	)
	)

	(array.set $i16array
	(local.get $expanded)
	(local.get $i)
	(array.get_u $i8array (local.get $arr) (local.get $i))
	)
	br $loop
	)
	)

	(call $fromCharCodeArray
	(local.get $expanded)
	(i32.const 0)
	(array.len (local.get $expanded))
	)
	)

	(func (export "stringFromCharCodeArray")
	(param $arr (ref $i16array))
	(param $start i32)
	(param $length i32)
	(result (ref extern))

	(call $fromCharCodeArray
	(local.get $arr)
	(local.get $start)
	(i32.add
	(local.get $start)
	(local.get $length)
	)
	)
	)
	)
	*/
	const _wasmStandaloneArrayHelper =
	'AGFzbQEAAAABIgVedwFeeAFgA2MAf38BZG9gA2QBf38BZG9gA2QAf38BZG8CJAEOd2FzbTpqcy1zdHJpbmcRZnJvbUNoYXJDb2RlQXJyYXkAAgMDAgMEBzICFHN0cmluZ0Zyb21Bc2NpaUJ5dGVzAAEXc3RyaW5nRnJvbUNoYXJDb2RlQXJyYXkAAgpTAkMCAX8BZAAgAiEDQQAgAvsGACEEAkADQCADQX9qIQMgAyABSA0BIAQgAyAAIAP7DQH7DgAMAAsACyAEQQAgBPsPEAALDQAgACABIAEgAmoQAAs=';

	String dart2wasmHtml(
	String title,
	String wasmPath,
	String mjsPath,
	String supportJsPath,
	bool standalone,
	) {
	const standaloneEmbedder =
	"""
	const { instance: helperInstance } = await WebAssembly.instantiate(Uint8Array.fromBase64('$_wasmStandaloneArrayHelper'), {}, {
	builtins: ['js-string']
	});

	const dartEmbedder = {
	// See sdk/lib/_internal/wasm_standalone/lib/embedder.dart for required definitions.
	scheduleOnce: (delayInMicros, callback, arg) => {
	const timeout = setTimeout(() => callback(arg), Number(delayInMicros / 1000n));
	return {timeout};
	},
	scheduleRepeated: (intervalMicros, callback, arg) => {
	const timeout = setInterval(() => callback(arg), Number(intervalMicros / 1000n));
	return {timeout};
	},
	queueMicrotask: (callback, arg) => {
	queueMicrotask(() => callback(arg));
	},
	clearSchedule: (schedule) => {
	clearTimeout(schedule.timeout);
	},
	currentTime: () => BigInt(Date.now()) * 1000n,
	stringFromAsciiBytes: (chars, start, length) => {
	const str = helperInstance.exports.stringFromAsciiBytes(chars, start, length);
	return str;
	},
	stringFromCharCodeArray: (chars, start, length) => {
	const str = helperInstance.exports.stringFromCharCodeArray(chars, start, length);
	return str;
	},
	monotonicClockFrequency: () => 1_000_000,
	monotonicClockTicks: () => BigInt(Math.round(performance.now() * 1000)),
	weakRefCreate: (dartValue) => new WeakRef(dartValue),
	weakRefGet: (weakRef) => weakRef.deref() ?? null,
	expandoCreate: () => new WeakMap(),
	expandoGet: (expando, target, _hash) => expando.get(target) ?? null,
	expandoSet: (expando, target, _hash, value) => expando.set(target, value),
	finalizerCreate: (callback, firstParameter) => {
	return new FinalizationRegistry((heldValue) => {
	callback(heldValue, firstParameter);
	});
	},
	finalizerAttach: (finalizer, object, token, detachToken) => {
	if (detachToken) {
	finalizer.register(object, token, detachToken);
	} else {
	finalizer.register(object, token);
	}
	},
	finalizerDetach: (finalizer, detachToken) => finalizer.unregister(detachToken),
	baseUri: () => globalThis.location.href,
	isWindows: () => false,
	stackTraceGetCurrent: () => new Error().stack,
	stackTraceToString: (trace) => {
	const stackString = trace.toString();
	const frames = stackString.split('\\n');
	// Format of stack traces is:
	// 1. stackTraceGetCurrent (from this embedder object)
	// 2. module0.StackTrace.current <noInline>
	// 3. The callsite we care about.
	const drop = 1 + frames.findIndex((l) => l.indexOf('stackTraceGetCurrent') > 0);
	return frames.slice(drop).join('\\n');
	},
	doubleTryParse: (source) => {
	if (!/${r'^\s[+-]?(?:Infinity\|NaN\|(?:\.\d+\|\d+(?:\.\d)?)(?:[eE][+-]?\d+)?)\s*$'}/.test(source)) {
	const trimmed = source.trim();
	// parseFloat is more lenient than double.tryParse, see wasm/lib/double_patch.dart for details.
	if (!(trimmed == 'NaN' \|\| trimmed == '+NaN' \|\| trimmed == '-NaN')) {
	return null;
	}
	return { result: NaN };
	} else {
	return { result: parseFloat(source) };
	}
	},
	tryParseResultGetDouble: ({result}) => result,
	i64ToString: (source, radix) => source.toString(radix),
	f64ToExponential: (source) => source.toExponential(),
	f64ToExponentialWithFractionDigits: (source, digits) => {
	return source.toExponential(digits);
	},
	f64ToPrecision: (source, digits) => source.toPrecision(digits),
	f64ToFixed: (source, digits) => source.toFixed(digits),
	f64ToString: (source) => {
	if (Object.is(source, -0)) return '-0.0';
	if (Number.isNaN(source)) return 'NaN';
	if (source == Number.NEGATIVE_INFINITY) return '-Infinity';
	if (source == Number.POSITIVE_INFINITY) return 'Infinity';

	let formatted = source.toString();
	if (source % 1.0 == 0 && formatted.indexOf('e') == -1) {
	formatted += '.0';
	}
	return formatted;
	},
	stringBufferCreate: () => ({ contents: '' }),
	stringBufferWriteString: (buffer, append) => {
	buffer.contents += append;
	},
	stringBufferWriteCharCode: (buffer, code) => {
	buffer.contents += String.fromCodePoint(code);
	},
	stringBufferClear: (buffer) => {
	buffer.contents = ''
	},
	stringBufferLength: (buffer) => buffer.contents.length,
	stringBufferToString: ({contents}) => contents,
	regexpCreateOrFailWithString: (pattern, multiLine, caseSensitive, unicode, dotAll) => {
	let flags = '';
	if (multiLine) flags += 'm';
	if (!caseSensitive) flags += 'i';
	if (unicode) flags += 'u';
	if (dotAll) flags += 's';

	try {
	// Prepare two regular expressions, one for regular matches and one
	// for matchAsPrefix.
	return {
	regular: new RegExp(pattern, flags + 'g'),
	asPrefix: new RegExp(pattern, flags + 'y'),
	};
	} catch (e) {
	return String(e);
	}
	},
	regexpIsRegexp: (source) => typeof(source) !== 'string',
	regexpEscape: (source) => {
	// Note: We can't use RegExp.escape here, it escapes too much and we
	// have tests expecting that e.g. \t isn't escaped.
	if (/${r'[[\]{}()*+?.\\^$\|]'}/.test(source)) {
	return source.replace(/${r'[[\]{}()*+?.\\^$\|]'}/g, "${r'\\$&'}");
	} else {
	return source;
	}
	},
	regexpMatch: (regexp, string, start, asPrefix) => {
	const regex = asPrefix ? regexp.asPrefix : regexp.regular;
	regex.lastIndex = start;
	const match = regex.exec(string);
	if (match) {
	return {
	start: match.index,
	end: match.index + match[0].length,
	groupNames: match.groups ? Object.keys(match.groups) : [],
	groups: match,
	};
	} else {
	return null;
	}
	},
	regexpMatchGetStart: (match) => match.start,
	regexpMatchGetEnd: (match) => match.end,
	regexpMatchGetGroupCount: (match) => match.groups.length - 1,
	regexpMatchGetGroup: (match, index) => match.groups[index] ?? null,
	regexpMatchGetNamedGroups: (match) => match.groupNames.length,
	regexpMatchGetGroupName: (match, index) => match.groupNames[index],
	regexpMatchGetGroupByName: (match, index) => match.groups.groups[match.groupNames[index]] ?? null,
	timeZoneNameForClampedSeconds: (secondsSinceEpoch) => {
	const date = new Date(Number(secondsSinceEpoch * 1000n));
	const match = /\\((.*)\\)/.exec(date.toString());
	if (match == null) {
	// This should never happen on any recent browser.
	return '';
	}
	return match[1];
	},
	timeZoneOffsetInSecondsForClampedSeconds: (secondsSinceEpoch) => {
	const date = new Date(Number(secondsSinceEpoch * 1000n));
	// This needs to be negated because Dart wants the difference between
	// local time and UTC.
	return -date.getTimezoneOffset() * 60;
	},
	};
	""";
	final additionalImports = standalone ? '{ dart: dartEmbedder }' : '{}';

	return """
	<!DOCTYPE html>
	<html>
	<head>
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta charset="utf-8">
	<meta name="dart.unittest" content="full-stack-traces">
	<title> Test $title </title>
	<link rel="preload" href="$wasmPath" as="fetch" crossorigin>
	<style>
	.unittest-table { font-family:monospace; border:1px; }
	.unittest-pass { background: #6b3;}
	.unittest-fail { background: #d55;}
	.unittest-error { background: #a11;}
	</style>
	</head>
	<body>
	<h1> Running $title </h1>
	<script type="text/javascript"
	src="/root_dart/pkg/test_runner/lib/src/test_controller.js">
	</script>
	<script type="module">
	// Default stack trace limit in V8 is 10, which hides some of the stack frames
	// we check in stack trace tests.
	Error.stackTraceLimit = 20;
	async function loadAndRun(mjsPath, wasmPath, supportJsPath) {
	const supportJSExpression = await (await fetch(supportJsPath)).text();
	const support = eval(supportJSExpression);
	if (support !== true) {
	dartMainRunner(() => {
	throw 'This browser does not support the required features to run the dart2wasm compiled app!';
	});
	return;
	}

	const mjs = await import(mjsPath);
	const compiledApp = await mjs.compileStreaming(fetch(wasmPath));
	window.loadData = async (relativeToWasmFileUri) => {
	const path = '$wasmPath'.slice(0, wasmPath.lastIndexOf('/'));
	const response = await fetch(`\${path}/\${relativeToWasmFileUri}`);
	return response.arrayBuffer();
	};
	${standalone ? standaloneEmbedder : ''}
	const appInstance = await compiledApp.instantiate($additionalImports, {
	loadDeferredModules: (modules, handleWasmBytes) =>
	Promise.all(modules.map((m) => fetch(m).then((b) => handleWasmBytes(m, b)))),
	});
	dartMainRunner(() => {
	appInstance.invokeMain();
	});
	}

	loadAndRun('$mjsPath', '$wasmPath', '$supportJsPath');
	</script>
	</body>
	</html>""";
	}