Better logging in random_test.dart, and less overall noise from warnings

lib/src/editor.dart

@@ -574,7 +574,7 @@ class YamlEditor {
           _yaml);
     }
 
-    final actualTree = loadYamlNode(_yaml);
+    final actualTree = withYamlWarningCallback(() => loadYamlNode(_yaml));
     if (!deepEquals(actualTree, expectedTree)) {
       throw createAssertionError(
           'Modification did not result in expected result.',

lib/src/utils.dart

@@ -8,14 +8,34 @@ import 'package:yaml/yaml.dart';
 import 'editor.dart';
 import 'wrap.dart';
 
+/// Invoke [fn] while setting [yamlWarningCallback] to [warn], and restore
+/// [YamlWarningCallback] after [fn] returns.
+///
+/// Defaults to a [warn] function that ignores all warnings.
+T withYamlWarningCallback<T>(
+  T Function() fn, {
+  YamlWarningCallback warn = _ignoreWarning,
+}) {
+  final original = yamlWarningCallback;
+  try {
+    yamlWarningCallback = warn;
+    return fn();
+  } finally {
+    yamlWarningCallback = original;
+  }
+}
+
+void _ignoreWarning(String warning, [SourceSpan? span]) {/* ignore warning */}
+
 /// Determines if [string] is dangerous by checking if parsing the plain string
 /// can return a result different from [string].
 ///
 /// This function is also capable of detecting if non-printable characters are
 /// in [string].
 bool isDangerousString(String string) {
   try {
-    if (loadYamlNode(string).value != string) {
+    final node = withYamlWarningCallback(() => loadYamlNode(string));
+    if (node.value != string) {
       return true;
     }
 

test/random_test.dart

@@ -2,8 +2,7 @@
 // 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 'dart:async';
-import 'dart:math';
+import 'dart:math' show Random;
 
 import 'package:test/test.dart';
 import 'package:yaml/yaml.dart';
@@ -44,15 +43,10 @@ dev_dependencies:
 ''');
 
       for (var j = 0; j < modificationsPerRound; j++) {
-        /// Using [runZoned] to hide `package:yaml`'s warnings.
-        /// Test failures and errors will still be shown.
-        runZoned(() {
-          expect(
-              () => generator.performNextModification(editor), returnsNormally);
-        },
-            zoneSpecification: ZoneSpecification(
-                print: (Zone self, ZoneDelegate parent, Zone zone,
-                    String message) {}));
+        expect(
+          () => generator.performNextModification(editor),
+          returnsNormally,
+        );
       }
     });
   }