Fix validation check within Utf8JsonWriter for writing a primitive v…

…alue after another complete value has been written. (dotnet/corefx#39796)

* Fix validation check within Utf8JsonWriter for writing a primitive
value.

* Update the unit test to pass in JsonValueKind as an inlinedata option.

* Test cleanup.

* Remove use of _isNotPrimitive as that is redundant and unnecessary.

* Some more test clean up - validate bytespending moves.

* More test clean up - ensure bytespending remains as is when we throw.

* Invert check order to rely on short-circuiting.

* Address feedback and add comment related tests.


Commit migrated from dotnet/corefx@47c35fe

src/libraries/System.Text.Json/src/Resources/Strings.resx

@@ -156,8 +156,8 @@
   <data name="CannotWritePropertyAfterProperty" xml:space="preserve">
     <value>Cannot write a JSON property name following another property name. A JSON value is missing.</value>
   </data>
-  <data name="CannotWriteValueAfterPrimitive" xml:space="preserve">
-    <value>Cannot write a JSON value after a single JSON value. Current token type is '{0}'.</value>
+  <data name="CannotWriteValueAfterPrimitiveOrClose" xml:space="preserve">
+    <value>Cannot write a JSON value after a single JSON value or outside of an existing closed object/array. Current token type is '{0}'.</value>
   </data>
   <data name="CannotWriteValueWithinObject" xml:space="preserve">
     <value>Cannot write a JSON value within an object without a property name. Current token type is '{0}'.</value>
@@ -423,4 +423,4 @@
   <data name="FormatUInt16" xml:space="preserve">
     <value>Either the JSON value is not in a supported format, or is out of bounds for a UInt16.</value>
   </data>
-</root>
+</root>

src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.cs

@@ -496,8 +496,8 @@ private static string GetResourceString(ExceptionResource resource, int currentD
                         SR.Format(SR.CannotWritePropertyAfterProperty) :
                         SR.Format(SR.CannotWritePropertyWithinArray, tokenType);
                     break;
-                case ExceptionResource.CannotWriteValueAfterPrimitive:
-                    message = SR.Format(SR.CannotWriteValueAfterPrimitive, tokenType);
+                case ExceptionResource.CannotWriteValueAfterPrimitiveOrClose:
+                    message = SR.Format(SR.CannotWriteValueAfterPrimitiveOrClose, tokenType);
                     break;
                 default:
                     Debug.Fail($"The ExceptionResource enum value: {resource} is not part of the switch. Add the appropriate case and exception message.");
@@ -623,7 +623,7 @@ internal enum ExceptionResource
         CannotStartObjectArrayWithoutProperty,
         CannotStartObjectArrayAfterPrimitiveOrClose,
         CannotWriteValueWithinObject,
-        CannotWriteValueAfterPrimitive,
+        CannotWriteValueAfterPrimitiveOrClose,
         CannotWritePropertyWithinArray,
         ExpectedJsonTokens,
         TrailingCommaNotAllowedBeforeArrayEnd,

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.WriteValues.Helpers.cs

@@ -26,9 +26,11 @@ private void ValidateWritingValue()
                 else
                 {
                     Debug.Assert(_tokenType != JsonTokenType.PropertyName);
-                    if (!_isNotPrimitive && _tokenType != JsonTokenType.None)
+
+                    // It is more likely for CurrentDepth to not equal 0 when writing valid JSON, so check that first to rely on short-circuiting and return quickly.
+                    if (CurrentDepth == 0 && _tokenType != JsonTokenType.None)
                     {
-                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.CannotWriteValueAfterPrimitive, currentDepth: default, token: default, _tokenType);
+                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.CannotWriteValueAfterPrimitiveOrClose, currentDepth: default, token: default, _tokenType);
                     }
                 }
             }

src/libraries/System.Text.Json/src/System/Text/Json/Writer/Utf8JsonWriter.cs

@@ -48,7 +48,6 @@ public sealed partial class Utf8JsonWriter : IDisposable, IAsyncDisposable
         private Memory<byte> _memory;
 
         private bool _inObject;
-        private bool _isNotPrimitive;
         private JsonTokenType _tokenType;
         private BitStack _bitStack;
 
@@ -116,7 +115,6 @@ public Utf8JsonWriter(IBufferWriter<byte> bufferWriter, JsonWriterOptions option
             _memory = default;
 
             _inObject = default;
-            _isNotPrimitive = default;
             _tokenType = default;
             _currentDepth = default;
             _options = options;
@@ -152,7 +150,6 @@ public Utf8JsonWriter(Stream utf8Json, JsonWriterOptions options = default)
             _memory = default;
 
             _inObject = default;
-            _isNotPrimitive = default;
             _tokenType = default;
             _currentDepth = default;
             _options = options;
@@ -249,7 +246,6 @@ private void ResetHelper()
             _memory = default;
 
             _inObject = default;
-            _isNotPrimitive = default;
             _tokenType = default;
             _currentDepth = default;
 
@@ -470,7 +466,6 @@ private void WriteStart(byte token)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
         }
 
         private void WriteStartMinimized(byte token)
@@ -524,7 +519,9 @@ private void ValidateStart()
             {
                 Debug.Assert(_tokenType != JsonTokenType.PropertyName);
                 Debug.Assert(_tokenType != JsonTokenType.StartObject);
-                if (_tokenType != JsonTokenType.None && (!_isNotPrimitive || CurrentDepth == 0))
+
+                // It is more likely for CurrentDepth to not equal 0 when writing valid JSON, so check that first to rely on short-circuiting and return quickly.
+                if (CurrentDepth == 0 && _tokenType != JsonTokenType.None)
                 {
                     ThrowHelper.ThrowInvalidOperationException(ExceptionResource.CannotStartObjectArrayAfterPrimitiveOrClose, currentDepth: default, token: default, _tokenType);
                 }
@@ -602,7 +599,6 @@ private void WriteStartHelper(ReadOnlySpan<byte> utf8PropertyName, byte token)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
         }
 
         /// <summary>
@@ -627,7 +623,6 @@ public void WriteStartArray(ReadOnlySpan<byte> utf8PropertyName)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
             _tokenType = JsonTokenType.StartArray;
         }
 
@@ -653,7 +648,6 @@ public void WriteStartObject(ReadOnlySpan<byte> utf8PropertyName)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
             _tokenType = JsonTokenType.StartObject;
         }
 
@@ -772,7 +766,6 @@ public void WriteStartArray(ReadOnlySpan<char> propertyName)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
             _tokenType = JsonTokenType.StartArray;
         }
 
@@ -798,7 +791,6 @@ public void WriteStartObject(ReadOnlySpan<char> propertyName)
 
             _currentDepth &= JsonConstants.RemoveFlagsBitMask;
             _currentDepth++;
-            _isNotPrimitive = true;
             _tokenType = JsonTokenType.StartObject;
         }