diff --git a/test/co19/co19_test_base.dart b/test/co19/co19_test_base.dart
new file mode 100644
index 0000000000..c98183bb18
--- /dev/null
+++ b/test/co19/co19_test_base.dart
@@ -0,0 +1,69 @@
+// Copyright (c) 2025, 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:analyzer/file_system/file_system.dart';
+import 'package:dartdoc/src/dartdoc_options.dart';
+import 'package:dartdoc/src/model/model.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dartdoc_test_base.dart';
+import '../src/utils.dart' as utils;
+
+@reflectiveTest
+class Co19TestBase extends DartdocTestBase {
+  @override
+  String get libraryName => 'co19';
+
+  late Folder projectRoot;
+  late PackageGraph packageGraph;
+  late ModelElement libraryModel;
+
+  void expectNoWarnings() {
+    expect(packageGraph.packageWarningCounter.countedWarnings, isEmpty);
+    expect(packageGraph.packageWarningCounter.hasWarnings, isFalse);
+  }
+
+  Future<void> writePackageWithCommentedLibraries(
+    List<(String, String)> filesAndComments, {
+    List<String> additionalArguments = const [],
+  }) async {
+    projectRoot =
+        utils.writePackage('co19', resourceProvider, packageConfigProvider);
+    projectRoot
+        .getChildAssumingFile('dartdoc_options.yaml')
+        .writeAsStringSync('''
+      dartdoc:
+        warnings:
+          - missing-code-block-language
+      ''');
+
+    for (var (fileName, comment) in filesAndComments) {
+      projectRoot
+          .getChildAssumingFolder('lib')
+          .getChildAssumingFile(fileName)
+          .writeAsStringSync('$comment\n'
+              'library;');
+    }
+
+    var optionSet = DartdocOptionRoot.fromOptionGenerators(
+        'dartdoc', [createDartdocOptions], packageMetaProvider);
+    optionSet.parseArguments([]);
+    packageGraph = await utils.bootBasicPackage(
+        projectRoot.path, packageMetaProvider, packageConfigProvider,
+        additionalArguments: additionalArguments);
+    libraryModel = packageGraph.defaultPackage.libraries.first;
+  }
+
+  Future<void> writePackageWithCommentedLibrary(
+    String comment, {
+    List<String> additionalArguments = const [],
+  }) =>
+      writePackageWithCommentedLibraries([('a.dart', comment)],
+          additionalArguments: additionalArguments);
+
+  void expectDocComment(matcher) {
+    expect(libraryModel.documentation, matcher);
+  }
+}
diff --git a/test/co19/line_based_doc_comments_test.dart b/test/co19/line_based_doc_comments_test.dart
new file mode 100644
index 0000000000..1851454b2a
--- /dev/null
+++ b/test/co19/line_based_doc_comments_test.dart
@@ -0,0 +1,166 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion A line-based doc comment is a comment that starts with `///`. One
+/// or more consecutive lines that begin with `///` form a doc comment block.
+///
+/// The block continues even if interrupted by single-line non-doc comments
+/// (lines starting with `//`) or by blank lines. The interrupting lines are
+/// ignored when extracting documentation text.
+///
+/// For each line that begins with `///`, the parser removes the three slashes
+/// and all leading whitespace to produce the documentation text. Exception:
+/// inside fenced code blocks (` ``` `), whitespace after the leading `///` is
+/// preserved to maintain code formatting.
+/// @author sgrekhov22@gmail.com
+library;
+
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import 'co19_test_base.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(LineBasedDocCommentsTest);
+  });
+}
+
+@reflectiveTest
+class LineBasedDocCommentsTest extends Co19TestBase {
+  /// Check that the parser removes the three slashes and all leading
+  /// whitespaces
+  void test_removesTripleSlashes() async {
+    await writePackageWithCommentedLibrary('''
+/// Text.
+/// More text.
+''');
+    expectDocComment(equals('''
+Text.
+More text.'''));
+  }
+
+  /// Check empty lines after three slashes are preserved
+  void test_leavesBlankLines() async {
+    await writePackageWithCommentedLibrary('''
+/// Text.
+///
+/// More text.
+''');
+    expectDocComment(equals('''
+Text.
+
+More text.'''));
+  }
+
+  /// Check that the parser removes the three slashes and all leading
+  /// whitespaces
+  void test_removesSpaceAfterTripleSlashes() async {
+    markTestSkipped('Skipping until issue '
+        'https://github.com/dart-lang/dartdoc/issues/4137 is resolved.');
+    return;
+    await writePackageWithCommentedLibrary('''
+///  Text.
+///    More text.
+''');
+    expectDocComment(equals('''
+Text.
+More text.'''));
+  }
+
+  /// Check that interrupting blank lines and starting with `// ` are ignored.
+  void test_interruptingLinesIgnored() async {
+    await writePackageWithCommentedLibrary('''
+/// Text.
+//
+/// More text.
+// Some text
+/// And more text.
+
+/// And more.
+''');
+    expectDocComment(equals('''
+Text.
+More text.
+And more text.
+And more.'''));
+  }
+
+  /// Check that the doc comment starts after `///` even there is no trailing
+  /// whitespace.
+  void test_noTrailingWhitespace() async {
+    await writePackageWithCommentedLibrary('''
+//// Text.
+/////More text.
+///And more.
+''');
+    expectDocComment(equals('''
+/ Text.
+//More text.
+And more.'''));
+  }
+
+  /// Check that inside fenced code blocks (```), whitespaces after the leading
+  /// `///` are preserved
+  void test_whitespacesInBacktickCodeBlocks() async {
+    await writePackageWithCommentedLibrary('''
+/// ```
+/// void main() {
+///   /// This line prints "Hello, world!"
+///   print('Hello, world!');
+/// }
+/// ```
+''');
+    expectDocComment(equals('''
+```
+void main() {
+  /// This line prints "Hello, world!"
+  print('Hello, world!');
+}
+```'''));
+  }
+
+  /// Check that inside fenced code blocks (~~~), whitespaces after the leading
+  /// `///` are preserved
+  void test_whitespacesInTildesCodeBlocks() async {
+    await writePackageWithCommentedLibrary('''
+/// ~~~
+/// void main() {
+///   /// This line prints "Hello, world!"
+///   print('Hello, world!');
+/// }
+/// ~~~
+''');
+    expectDocComment(equals('''
+~~~
+void main() {
+  /// This line prints "Hello, world!"
+  print('Hello, world!');
+}
+~~~'''));
+  }
+
+  /// Check that inside fenced code span (`), whitespaces after the leading
+  /// `///` are removed.
+  void test_whitespacesInCodeSpan() async {
+    markTestSkipped('Skipping until issue '
+        'https://github.com/dart-lang/dartdoc/issues/4138 is resolved.');
+    return;
+    await writePackageWithCommentedLibrary('''
+/// `
+/// void main() {
+///   /// This line prints "Hello, world!"
+///   print('Hello, world!');
+/// }
+/// `
+''');
+    expectDocComment(equals('''
+`
+void main() {
+/// This line prints "Hello, world!"
+print('Hello, world!');
+}
+`'''));
+  }
+}
diff --git a/test/dartdoc_test_base.dart b/test/dartdoc_test_base.dart
index be046a1569..5b4c34e0a7 100644
--- a/test/dartdoc_test_base.dart
+++ b/test/dartdoc_test_base.dart
@@ -40,7 +40,7 @@ abstract class DartdocTestBase {
 
   String get dartCoreUrlPrefix => '$dartSdkUrlPrefix/dart-core';
 
-  String get dartSdkUrlPrefix => 'https://api.dart.dev/stable/3.2.0';
+  String get dartSdkUrlPrefix => 'https://api.dart.dev/stable/3.10.6';
 
   String get sdkConstraint => '>=3.7.0 <4.0.0';