Fix for writing DateTimeOffset values

src/Microsoft.OpenApi.Readers/ParseNodes/ValueNode.cs

@@ -29,7 +29,7 @@ public override string GetScalarValue()
             }
 
             return scalarNode.Value;
-        }
+       }
 
         /// <summary>
         /// Create a <see cref="IOpenApiPrimitive"/>
@@ -59,11 +59,18 @@ public override IOpenApiAny CreateAny()
                 return new OpenApiInteger(intValue);
             }
 
+            if (long.TryParse(value, out var longValue))
+            {
+                return
+                    new OpenApiLong(
+                        longValue); 
+            }
+
             if (double.TryParse(value, out var dblValue))
             {
                 return
                     new OpenApiDouble(
-                        dblValue); // Note(darrmi): This may be better as decimal.  Further investigation required.
+                        dblValue); // Note(darrmi): This may be better as decimal. Further investigation required.
             }
 
             if (DateTimeOffset.TryParse(value, out var datetimeValue))
@@ -75,4 +82,4 @@ public override IOpenApiAny CreateAny()
             return new OpenApiString(value);
         }
     }
-}
+}

src/Microsoft.OpenApi/Writers/OpenApiWriterBase.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
+using System;
 using System.Collections.Generic;
 using System.IO;
 using Microsoft.OpenApi.Exceptions;
@@ -162,6 +163,16 @@ public virtual void WriteValue(long value)
             Writer.Write(value);
         }
 
+        /// <summary>
+        /// Write dateTimeOffset value.
+        /// </summary>
+        /// <param name="value">The decimal value.</param>
+        public virtual void WriteValue(DateTimeOffset value)
+        {
+            WriteValueSeparator();
+            Writer.Write(value.ToString("o"));
+        }
+
         /// <summary>
         /// Write boolean value.
         /// </summary>
@@ -214,6 +225,10 @@ public virtual void WriteValue(object value)
             {
                 WriteValue((decimal)value);
             }
+            else if (type == typeof(DateTimeOffset) || type == typeof(DateTimeOffset?))
+            {
+                WriteValue((DateTimeOffset)value);
+            }
             else
             {
                 throw new OpenApiWriterException(string.Format(SRResource.OpenApiUnsupportedValueType, type.FullName));

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiAnyTests.cs

@@ -80,7 +80,7 @@ public void ParseListAsAnyShouldSucceed()
         }
 
         [Fact]
-        public void ParseScalarIntegertAsAnyShouldSucceed()
+        public void ParseScalarIntegerAsAnyShouldSucceed()
         {
             var input = @"
 10
@@ -102,5 +102,29 @@ public void ParseScalarIntegertAsAnyShouldSucceed()
                 new OpenApiInteger(10)
             );
         }
+
+        [Fact]
+        public void ParseScalarDateTimeAsAnyShouldSucceed()
+        {
+            var input = @"
+2012-07-23T12:33:00
+                ";
+            var yamlStream = new YamlStream();
+            yamlStream.Load(new StringReader(input));
+            var yamlNode = yamlStream.Documents.First().RootNode;
+
+            var context = new ParsingContext();
+            var diagnostic = new OpenApiDiagnostic();
+
+            var node = new ValueNode(context, diagnostic, (YamlScalarNode)yamlNode);
+
+            var any = node.CreateAny();
+
+            diagnostic.Errors.Should().BeEmpty();
+
+            any.ShouldBeEquivalentTo(
+                new OpenApiDateTime(DateTimeOffset.Parse("2012-07-23T12:33:00"))
+            );
+        }
     }
 }

test/Microsoft.OpenApi.Tests/Writers/OpenApiWriterAnyExtensionsTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
+using System;
 using System.IO;
 using FluentAssertions;
 using Microsoft.OpenApi.Any;
@@ -84,6 +85,23 @@ public void WriteOpenApiDoubleAsJsonWorks(double input)
             json.Should().Be(input.ToString());
         }
 
+        [Theory]
+        [InlineData("2017-1-2")]
+        [InlineData("1999-01-02T12:10:22")]
+        [InlineData("1999-01-03")]
+        [InlineData("10:30:12")]
+        public void WriteOpenApiDateTimeAsJsonWorks(string inputString)
+        {
+            // Arrange
+            var input = DateTimeOffset.Parse(inputString);
+            var dateTimeValue = new OpenApiDateTime(input);
+
+            var json = WriteAsJson(dateTimeValue);
+
+            // Assert
+            json.Should().Be(input.ToString("o"));
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]