Fix RootFilter to proper return an IEnumerable containing the root JToken rather than the root JToken itself as an IEnumerable

Src/Newtonsoft.Json.Tests/Linq/JsonPath/JPathExecuteTests.cs

@@ -1271,11 +1271,85 @@ namespace Newtonsoft.Json.Tests.Linq.JsonPath
 
             JArray a = JArray.Parse(json);
 
-            List<JToken> result = a.SelectTokens("$.[?($.store.bicycle.price < 20)]").ToList();
+            List<JToken> result = a.SelectTokens("$.[?($.[0].store.bicycle.price < 20)]").ToList();
             Assert.AreEqual(1, result.Count);
 
-            result = a.SelectTokens("$.[?($.store.bicycle.price < 10)]").ToList();
+            result = a.SelectTokens("$.[?($.[0].store.bicycle.price < 10)]").ToList();
             Assert.AreEqual(0, result.Count);
         }
+
+        [Test]
+        public void RootInFilterWithRootObject()
+        {
+            string json = @"{
+                ""store"" : {
+                    ""book"" : [
+                        {
+                            ""category"" : ""reference"",
+                            ""author"" : ""Nigel Rees"",
+                            ""title"" : ""Sayings of the Century"",
+                            ""price"" : 8.95
+                        },
+                        {
+                            ""category"" : ""fiction"",
+                            ""author"" : ""Evelyn Waugh"",
+                            ""title"" : ""Sword of Honour"",
+                            ""price"" : 12.99
+                        },
+                        {
+                            ""category"" : ""fiction"",
+                            ""author"" : ""Herman Melville"",
+                            ""title"" : ""Moby Dick"",
+                            ""isbn"" : ""0-553-21311-3"",
+                            ""price"" : 8.99
+                        },
+                        {
+                            ""category"" : ""fiction"",
+                            ""author"" : ""J. R. R. Tolkien"",
+                            ""title"" : ""The Lord of the Rings"",
+                            ""isbn"" : ""0-395-19395-8"",
+                            ""price"" : 22.99
+                        }
+                    ],
+                    ""bicycle"" : [
+                        {
+                            ""color"" : ""red"",
+                            ""price"" : 19.95
+                        }
+                    ]
+                },
+                ""expensive"" : 10
+            }";
+
+            JObject a = JObject.Parse(json);
+
+            List<JToken> result = a.SelectTokens("$..book[?(@.price <= $['expensive'])]").ToList();
+            Assert.AreEqual(2, result.Count);
+
+            result = a.SelectTokens("$.store..[?(@.price > $.expensive)]").ToList();
+            Assert.AreEqual(3, result.Count);
+        }
+
+        [Test]
+        public void RootInFilterWithInitializers()
+        {
+            JObject rootObject = new JObject
+            {
+                { "referenceDate", new JValue(DateTime.MinValue) },
+                {
+                    "dateObjectsArray",
+                    new JArray()
+                    {
+                        new JObject { { "date", new JValue(DateTime.MinValue) } },
+                        new JObject { { "date", new JValue(DateTime.MaxValue) } },
+                        new JObject { { "date", new JValue(DateTime.Now) } },
+                        new JObject { { "date", new JValue(DateTime.MinValue) } },
+                    }
+                }
+            };
+
+            List<JToken> result = rootObject.SelectTokens("$.dateObjectsArray[?(@.date == $.referenceDate)]").ToList();
+            Assert.AreEqual(2, result.Count);
+        }
     }
 }

Src/Newtonsoft.Json/Linq/JsonPath/RootFilter.cs

@@ -12,7 +12,7 @@ namespace Newtonsoft.Json.Linq.JsonPath
 
         public override IEnumerable<JToken> ExecuteFilter(JToken root, IEnumerable<JToken> current, bool errorWhenNoMatch)
         {
-            return root;
+            yield return root;
         }
     }
 }