Default Ut8fJsonReader.Read should return false. (dotnet/corefx#36112)

* Default Ut8fJsonReader.Read should return false.

* Address PR feedback.

Commit migrated from https://github.com/dotnet/corefx/commit/e929f9bb99649279d4aab06d300a8beef33411fa

diff --git a/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs b/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs
index 2a0a2d5..782a86e 100644 (file)
--- a/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs
+++ b/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.MultiSegment.cs
@@ -59,7 +59,7 @@ namespace System.Text.Json
                 _nextPosition = default;
                 _currentPosition = jsonData.Start;
                 _isLastSegment = isFinalBlock;
-                _isSingleSegment = true;
+                _isMultiSegment = false;
             }
             else
             {
@@ -84,7 +84,7 @@ namespace System.Text.Json
                 }
 
                 _isLastSegment = !jsonData.TryGet(ref _nextPosition, out _, advance: true) && isFinalBlock; // Don't re-order to avoid short-circuiting
-                _isSingleSegment = false;
+                _isMultiSegment = true;
             }
         }
 
@@ -268,7 +268,7 @@ namespace System.Text.Json
             ReadOnlyMemory<byte> memory = default;
             while (true)
             {
-                Debug.Assert(_isSingleSegment || _currentPosition.GetObject() != null);
+                Debug.Assert(!_isMultiSegment || _currentPosition.GetObject() != null);
                 SequencePosition copy = _currentPosition;
                 _currentPosition = _nextPosition;
                 bool noMoreData = !_sequence.TryGet(ref _nextPosition, out memory, advance: true);
@@ -285,7 +285,7 @@ namespace System.Text.Json
                 // _currentPosition needs to point to last non-empty segment
                 // Since memory.Length == 0, we need to revert back to previous.
                 _currentPosition = copy;
-                Debug.Assert(_isSingleSegment || _currentPosition.GetObject() != null);
+                Debug.Assert(!_isMultiSegment || _currentPosition.GetObject() != null);
             }
 
             if (_isFinalBlock)

diff --git a/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs b/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs
index 91c8377..fdaacf6 100644 (file)
--- a/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs
+++ b/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs
@@ -40,13 +40,13 @@ namespace System.Text.Json
         private long _totalConsumed;
         private bool _isLastSegment;
         internal bool _stringHasEscaping;
-        private readonly bool _isSingleSegment;
+        private readonly bool _isMultiSegment;
 
         private SequencePosition _nextPosition;
         private SequencePosition _currentPosition;
         private ReadOnlySequence<byte> _sequence;
 
-        private bool IsLastSpan => _isFinalBlock && (_isSingleSegment || _isLastSegment);
+        private bool IsLastSpan => _isFinalBlock && (!_isMultiSegment || _isLastSegment);
 
         /// <summary>
         /// Gets the value of the last processed token as a ReadOnlySpan&lt;byte&gt; slice
@@ -183,7 +183,7 @@ namespace System.Text.Json
             _consumed = 0;
             _totalConsumed = 0;
             _isLastSegment = _isFinalBlock;
-            _isSingleSegment = true;
+            _isMultiSegment = false;
 
             ValueSpan = ReadOnlySpan<byte>.Empty;
 
@@ -204,7 +204,7 @@ namespace System.Text.Json
         /// </exception>
         public bool Read()
         {
-            bool retVal = _isSingleSegment ? ReadSingleSegment() : ReadMultiSegment();
+            bool retVal = _isMultiSegment ? ReadMultiSegment() : ReadSingleSegment();
 
             if (!retVal)
             {

diff --git a/src/libraries/System.Text.Json/tests/JsonTestHelper.cs b/src/libraries/System.Text.Json/tests/JsonTestHelper.cs
index 6c31546..04ccfdd 100644 (file)
--- a/src/libraries/System.Text.Json/tests/JsonTestHelper.cs
+++ b/src/libraries/System.Text.Json/tests/JsonTestHelper.cs
@@ -577,5 +577,25 @@ namespace System.Text.Json.Tests
                 }
             }
         }
+
+        public delegate void AssertThrowsActionUt8fJsonReader(Utf8JsonReader json);
+
+        // Cannot use standard Assert.Throws() when testing Utf8JsonReader - ref structs and closures don't get along.
+        public static void AssertThrows<E>(Utf8JsonReader json, AssertThrowsActionUt8fJsonReader action) where E : Exception
+        {
+            try
+            {
+                action(json);
+                Assert.False(true, "Expected exception: " + typeof(E).GetType());
+            }
+            catch (E ex)
+            {
+                Assert.IsType<E>(ex);
+            }
+            catch (Exception wrongException)
+            {
+                Assert.False(true, "Wrong exception thrown: Expected " + typeof(E).GetType() + ": Actual: " + wrongException.GetType());
+            }
+        }
     }
 }

diff --git a/src/libraries/System.Text.Json/tests/Utf8JsonReaderTests.cs b/src/libraries/System.Text.Json/tests/Utf8JsonReaderTests.cs
index 806856d..431b6c5 100644 (file)
--- a/src/libraries/System.Text.Json/tests/Utf8JsonReaderTests.cs
+++ b/src/libraries/System.Text.Json/tests/Utf8JsonReaderTests.cs
@@ -14,6 +14,79 @@ namespace System.Text.Json.Tests
 {
     public static partial class Utf8JsonReaderTests
     {
+        [Fact]
+        public static void DefaultUtf8JsonReader()
+        {
+            Utf8JsonReader json = default;
+
+            Assert.Equal(0, json.BytesConsumed);
+            Assert.Equal(0, json.CurrentDepth);
+            Assert.Equal(JsonTokenType.None, json.TokenType);
+            Assert.Equal(default, json.Position);
+            Assert.True(json.ValueSpan.SequenceEqual(default));
+            Assert.False(json.HasValueSequence);
+            Assert.True(json.ValueSequence.IsEmpty);
+
+            Assert.Equal(0, json.CurrentState.BytesConsumed);
+            Assert.Equal(default, json.CurrentState.Position);
+            Assert.Equal(0, json.CurrentState.Options.MaxDepth);
+            Assert.Equal(JsonCommentHandling.Disallow, json.CurrentState.Options.CommentHandling);
+
+            Assert.False(json.Read());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TextEquals("".AsSpan()));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TextEquals(default(ReadOnlySpan<char>)));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TextEquals(default(ReadOnlySpan<byte>)));
+
+            TestGetMethodsOnDefault();
+        }
+
+        private static void TestGetMethodsOnDefault()
+        {
+            Utf8JsonReader json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetDateTime(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetDateTime());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetDateTimeOffset(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetDateTimeOffset());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetDecimal(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetDecimal());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetDouble(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetDouble());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetInt32(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetInt32());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetInt64(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetInt64());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetSingle(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetSingle());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetUInt32(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetUInt32());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.TryGetUInt64(out _));
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetUInt64());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetString());
+
+            json = default;
+            JsonTestHelper.AssertThrows<InvalidOperationException>(json, (jsonReader) => jsonReader.GetBoolean());
+        }
+
         // TestCaseType is only used to give the json strings a descriptive name.
         [Theory]
         [MemberData(nameof(TestCases))]