Use the canonical URL instead of a data: URL for sourceMapUrl fallback

Author: ntkme

lib/src/importer/result.dart

@@ -2,8 +2,6 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'dart:convert';
-
 import 'package:meta/meta.dart';
 
 import '../importer.dart';
@@ -17,15 +15,8 @@ class ImporterResult {
   /// The contents of the stylesheet.
   final String contents;
 
-  /// An absolute, browser-accessible URL indicating the resolved location of
-  /// the imported stylesheet.
-  ///
-  /// This should be a `file:` URL if one is available, but an `http:` URL is
-  /// acceptable as well. If no URL is supplied, a `data:` URL is generated
-  /// automatically from [contents].
-  Uri get sourceMapUrl =>
-      _sourceMapUrl ?? Uri.dataFromString(contents, encoding: utf8);
-  final Uri? _sourceMapUrl;
+  /// An absolute URL indicating the resolved location of the imported stylesheet.
+  final Uri? sourceMapUrl;
 
   /// The syntax to use to parse the stylesheet.
   final Syntax syntax;
@@ -40,11 +31,10 @@ class ImporterResult {
   /// parameter instead.
   ImporterResult(
     this.contents, {
-    Uri? sourceMapUrl,
+    this.sourceMapUrl,
     Syntax? syntax,
     @Deprecated("Use the syntax parameter instead.") bool? indented,
-  })  : _sourceMapUrl = sourceMapUrl,
-        syntax = syntax ?? (indented == true ? Syntax.sass : Syntax.scss) {
+  }) : syntax = syntax ?? (indented == true ? Syntax.sass : Syntax.scss) {
     if (sourceMapUrl?.scheme == '') {
       throw ArgumentError.value(
         sourceMapUrl,

test/dart_api/importer_test.dart

@@ -5,7 +5,6 @@
 @TestOn('vm')
 library;
 
-import 'dart:convert';
 
 import 'package:test/test.dart';
 
@@ -305,7 +304,7 @@ void main() {
     expect(result.sourceMap!.urls, contains("u:blue"));
   });
 
-  test("uses a data: source map URL if the importer doesn't provide one", () {
+  test("uses the canonical URL if the importer doesn't provide one", () {
     var result = compileStringToResult(
       '@use "orange";',
       importers: [
@@ -320,10 +319,7 @@ void main() {
     expect(
       result.sourceMap!.urls,
       contains(
-        Uri.dataFromString(
-          ".orange {color: orange}",
-          encoding: utf8,
-        ).toString(),
+        "u:orange",
       ),
     );
   });

test/embedded/importer_test.dart

@@ -648,7 +648,8 @@ void main() {
       await process.close();
     });
 
-    test("uses a data: URL rather than an empty source map URL", () async {
+    test("uses the canonical URL rather than an empty source map URL",
+        () async {
       process.send(
         compileString(
           "@use 'other'",
@@ -673,7 +674,7 @@ void main() {
         "a { b: c; }",
         sourceMap: (String map) {
           var mapping = source_maps.parse(map) as source_maps.SingleMapping;
-          expect(mapping.urls, [startsWith("data:")]);
+          expect(mapping.urls, contains("custom:other"));
         },
       );
       await process.close();