Author fuzz tests and fix a comment-related issue (#2935)

Co-authored-by: James Newton-King <james@newtonking.com>

Src/Newtonsoft.Json.Tests/FuzzRegressionTests.cs

@@ -0,0 +1,127 @@
+#region License
+// Copyright (c) 2007 James Newton-King
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+#endregion
+
+using System.IO;
+
+#if DNXCORE50
+using Xunit;
+using Test = Xunit.FactAttribute;
+using Assert = Newtonsoft.Json.Tests.XUnitAssert;
+#else
+using NUnit.Framework;
+#endif
+
+#pragma warning disable xUnit1013
+
+namespace Newtonsoft.Json.Tests
+{
+    [TestFixture]
+    public class FuzzRegressionTests : TestFixtureBase
+    {
+        private static readonly JsonSerializer jsonSerializer = new();
+
+        public static void Roundtrip(string buffer)
+        {
+            var serialized1 = Serialize(Deserialize(buffer));
+            var serialized2 = Serialize(Deserialize(serialized1));
+            Assert.AreEqual(serialized1, serialized2);
+        }
+
+        private static string Serialize(object o)
+        {
+            using var sw1 = new StringWriter();
+            jsonSerializer.Serialize(sw1, o);
+            return sw1.ToString();
+        }
+
+        private static object Deserialize(string input)
+        {
+            using var sr = new StringReader(input);
+            using var tr = new JsonTextReader(sr);
+            return jsonSerializer.Deserialize(tr);
+        }
+
+        [Test]
+        public void LineCommentWithStarSlashCases()
+        {
+            // Fuzzer found these cases:
+            // The Json "// comment with */" would be serialized as "/* comment with */*/".
+            // It is now serialized as "// comment with */".
+            //
+            // Ideally this would be a [Theory] but we are targetting both NUnit and XUnit.
+            // 
+            // This is a list of inputs and where they caused a crash.
+            // - Note that these are not minimal/reduced inputs.
+            var cases = new[] {
+                "[//*/I33/\n91.//3", // ParsePositiveInfinity
+                "[//*/t3.9/\n91675795,77//3", // ParseTrue
+                "[//*/f33339/\n91675795878,787,[]//3", // ParseFalse
+                "[//*/N333331/\n,[]//3", // ParseNumberNaN
+                "[//*/{/\n,7//J:[@", // ParseProperty
+                "[//*/06.6/\n,[]//3", // ParseNumber
+                "[5,78,,[//*/3,3,new 4* ,,,,,,33/\n,,,,[],33,,,,,,17911055//3814", // ParseConstructor
+                "[//*/---------------------------------------------------------------------------------------------------------16.6/\n,[]//3", // ParseReadNumber
+                "[//6*/)3333/\n,[]//3", // ValidateEnd
+                "[//*/{'33/\n,33,33//3", // ReadStringIntoBuffer
+                "[//*//\n8 ,8 ", // ParseComment
+                @"[//ô   [ / 
+//""ÿ /'/*//// 
+//[7
+// 
+//"" @'/// 
+////
+//// 
+//[6
+//
+//
+//[1
+//
 ""  x
+
+///***
+   //[2
+// 
+,'/J ""' ", // WriteToken
+                "[2//***;****/,7*", // ReadNumberCharIntoBuffer
+                "[2///ÿ¢  ¢¢********/,,*		", // ParseValue
+                @"[// *//[
+7// 
+// ""JJ· 
+//',J
+ 
+// 
+//',o@7,7
+//',o@/ / "" ]      
+//',o@7,7
+//',o@Ó", // ParseComment
+                "[2//*/*", // ParsePostValue
+                "[//*/{A73/\n]1.//3:{\"'\":", //  ReadUnquotedPropertyReportIfDone
+            };
+
+            foreach (var c in cases) {
+                Roundtrip(c);
+            }
+        }
+    }
+}

Src/Newtonsoft.Json.Tests/JsonTextWriterTest.cs

@@ -1699,7 +1699,8 @@ null//comment
 
             w.WriteToken(r, true);
 
-            StringAssert.AreEqual(@"/*comment*//*hi*/*/{/*comment*/
+            StringAssert.AreEqual(@"//comment*//*hi*/
+{/*comment*/
   ""Name"": /*comment*/ true/*comment after true*//*comment after comma*/,
   ""ExpiryDate"": /*comment*/ new Constructor(
     /*comment*/,
@@ -1715,6 +1716,20 @@ null//comment
 }/*comment *//*comment 1 */", sw.ToString());
         }
 
+        [Test]
+        public void NewlinesInSingleLineComments()
+        {
+            // it’s not possible for this to be created by parsing JSON,
+            // but if someone gets creative with the API…
+            var sw = new StringWriter();
+            using (var w = new JsonTextWriter(sw))
+            {
+                w.WriteComment("*/\nsomething else");
+            }
+            
+            StringAssert.AreEqual("//*/\n//something else\n", sw.ToString());
+        }
+
         [Test]
         public void DisposeSupressesFinalization()
         {
@@ -1820,4 +1835,4 @@ null//comment
             throw new NotImplementedException();
         }
     }
-}
+}