fix: Observe serialization options in JsonEventFormatter for System.Text.Json

Fixes #225

Signed-off-by: Jon Skeet <[email protected]>

Author: jskeet

src/CloudNative.CloudEvents.SystemTextJson/JsonEventFormatter.cs

@@ -402,7 +402,7 @@ public override ReadOnlyMemory<byte> EncodeBatchModeMessage(IEnumerable<CloudEve
             };
 
             var stream = new MemoryStream();
-            var writer = new Utf8JsonWriter(stream);
+            var writer = CreateUtf8JsonWriter(stream);
             writer.WriteStartArray();
             foreach (var cloudEvent in cloudEvents)
             {
@@ -422,12 +422,24 @@ public override ReadOnlyMemory<byte> EncodeStructuredModeMessage(CloudEvent clou
             };
 
             var stream = new MemoryStream();
-            var writer = new Utf8JsonWriter(stream);
+            var writer = CreateUtf8JsonWriter(stream);
             WriteCloudEventForBatchOrStructuredMode(writer, cloudEvent);
             writer.Flush();
             return stream.ToArray();
         }
 
+        private Utf8JsonWriter CreateUtf8JsonWriter(Stream stream)
+        {
+            var options = new JsonWriterOptions
+            {
+                Encoder = SerializerOptions?.Encoder,
+                Indented = SerializerOptions?.WriteIndented ?? false,
+                // TODO: Consider skipping validation in the future for the sake of performance.
+                SkipValidation = false
+            };
+            return new Utf8JsonWriter(stream, options);
+        }
+
         private void WriteCloudEventForBatchOrStructuredMode(Utf8JsonWriter writer, CloudEvent cloudEvent)
         {
             Validation.CheckCloudEventArgument(cloudEvent, nameof(cloudEvent));

test/CloudNative.CloudEvents.UnitTests/SystemTextJson/JsonEventFormatterTest.cs

@@ -1087,6 +1087,21 @@ public void DecodeStructured_DefaultContentTypeToApplicationJson()
             Assert.Equal("some text", jsonData.GetString());
         }
 
+        [Fact]
+        public void EncodeStructured_IndentationSettings()
+        {
+            var cloudEvent = new CloudEvent().PopulateRequiredAttributes();
+            var formatter = new JsonEventFormatter(new JsonSerializerOptions
+            {
+                WriteIndented = true
+            }, new JsonDocumentOptions());
+            var encoded = formatter.EncodeStructuredModeMessage(cloudEvent, out _);
+            // Normalize the result to LF line endings.
+            var json = BinaryDataUtilities.GetString(encoded, Encoding.UTF8).Replace("\r\n", "\n").Replace("\r", "\n");
+            var expected = "{\n  \"specversion\": \"1.0\",\n  \"id\": \"test-id\",\n  \"source\": \"//test\",\n  \"type\": \"test-type\"\n}";
+            Assert.Equal(expected, json);
+        }
+
         // Utility methods
         private static object DecodeBinaryModeEventData(byte[] bytes, string contentType)
         {