Add tests and fixes for custom serialization involving unions

Author: marcospassos

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/ser/AvroWriteContext.java

@@ -87,7 +87,7 @@ public final AvroWriteContext createChildArrayContext() throws JsonMappingExcept
 
     public abstract AvroWriteContext createChildArrayContext(Object currValue) throws JsonMappingException;
 
-    public final AvroWriteContext createChildObjectContext() throws JsonMappingException {
+    public AvroWriteContext createChildObjectContext() throws JsonMappingException {
         return createChildObjectContext(null);
     }
 

avro/src/main/java/com/fasterxml/jackson/dataformat/avro/ser/ObjectWriteContext.java

@@ -32,6 +32,7 @@ public ObjectWriteContext(AvroWriteContext parent, AvroGenerator generator,
     @Override
     public Object rawValue() { return _record; }
 
+
     @Override
     public final AvroWriteContext createChildArrayContext(Object currValue)
     {
@@ -46,6 +47,18 @@ public final AvroWriteContext createChildArrayContext(Object currValue)
         return child;
     }
 
+    @Override
+    public AvroWriteContext createChildObjectContext() throws JsonMappingException {
+        _verifyValueWrite();
+        Schema.Field field = _findField();
+        if (field == null) { // unknown, to ignore
+            return new NopWriteContext(TYPE_OBJECT, this, _generator, null);
+        }
+        AvroWriteContext child = _createObjectContext(field.schema());
+        _record.put(_currentName, child.rawValue());
+        return child;
+    }
+
     @Override
     public AvroWriteContext createChildObjectContext(Object currValue) throws JsonMappingException {
         _verifyValueWrite();

avro/src/test/java/com/fasterxml/jackson/dataformat/avro/interop/annotations/CustomSerializationTest.java

@@ -0,0 +1,111 @@
+package com.fasterxml.jackson.dataformat.avro.interop.annotations;
+
+import java.io.IOException;
+import java.util.Objects;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.fasterxml.jackson.dataformat.avro.interop.annotations.UnionTest.Animal;
+import com.fasterxml.jackson.dataformat.avro.interop.annotations.UnionTest.Cat;
+import org.apache.avro.Schema;
+import org.apache.avro.SchemaBuilder;
+import org.junit.Test;
+
+import static com.fasterxml.jackson.dataformat.avro.interop.ApacheAvroInteropUtil.getApacheSchema;
+import static com.fasterxml.jackson.dataformat.avro.interop.ApacheAvroInteropUtil.jacksonDeserialize;
+import static com.fasterxml.jackson.dataformat.avro.interop.ApacheAvroInteropUtil.jacksonSerialize;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public final class CustomSerializationTest {
+    @JsonSerialize(using = House.Serializer.class)
+    @JsonDeserialize(using = House.Deserializer.class)
+    public final static class House {
+        public String ownerName;
+
+        public House(final String ownerName) {
+            this.ownerName = ownerName;
+        }
+
+        @Override
+        public boolean equals(final Object other) {
+            return other instanceof House && ownerName.equals(((House) other).ownerName);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(ownerName);
+        }
+
+        public static class Serializer extends JsonSerializer<House> {
+            @Override
+            public void serialize(
+                final House house,
+                final JsonGenerator generator,
+                final SerializerProvider serializers
+            ) throws IOException {
+                generator.writeStartObject();
+                generator.writeFieldName("owner");
+                generator.writeStartObject();
+                generator.writeFieldName("name");
+                generator.writeObject(house.ownerName);
+                generator.writeEndObject();
+                generator.writeEndObject();
+            }
+        }
+
+        public static class Deserializer extends JsonDeserializer<House> {
+            @Override
+            public House deserialize(
+                final JsonParser parser,
+                final DeserializationContext context
+            ) throws IOException {
+                // startObject
+                parser.nextToken();
+                // fieldName("owner")
+                parser.nextToken();
+                // writeStartObject
+                parser.nextToken();
+                // fieldName("name")
+                parser.nextToken();
+
+                String ownerName = parser.readValueAs(String.class);
+
+                // endObject
+                parser.nextToken();
+                // endObject
+                parser.nextToken();
+
+                return new House(ownerName);
+            }
+        }
+    }
+
+    @Test
+    public void testUnionCustomDeSerialization() throws IOException {
+        Schema schema = SchemaBuilder.builder(House.class.getPackage().getName())
+            .record(House.class.getSimpleName())
+            .fields()
+            .name("owner")
+            .type()
+            .optional()
+            .record("Owner")
+                .fields()
+                .name("name")
+                .type().nullable().stringType()
+                .noDefault()
+            .endRecord()
+            .endRecord();
+
+        House house = new House("Jackson");
+
+        byte[] bytes = jacksonSerialize(schema, house);
+        House result = jacksonDeserialize(schema, House.class, bytes);
+
+        assertThat(result).isEqualTo(house);
+    }
+}