refactor: privatize the avro schema property and add helpers

src/LEGO.AsyncAPI/Models/AsyncApiAvroSchemaPayload.cs

@@ -4,30 +4,43 @@ namespace LEGO.AsyncAPI.Models
 {
     using LEGO.AsyncAPI.Models.Interfaces;
     using LEGO.AsyncAPI.Writers;
+    using System;
 
     public class AsyncApiAvroSchemaPayload : IAsyncApiMessagePayload
     {
-        public AvroSchema Schema { get; set; }
+        private readonly AvroSchema schema;
 
         public AsyncApiAvroSchemaPayload(AvroSchema schema)
         {
-            this.Schema = schema;
+            this.schema = schema;
         }
 
         public AsyncApiAvroSchemaPayload()
         {
+            this.schema = new AvroRecord();
         }
 
         public bool TryGetAs<T>(out T schema)
             where T : AvroSchema
         {
-            schema = this.Schema as T;
+            schema = this.schema as T;
             return schema != null;
         }
 
-        public bool UnresolvedReference { get => this.Schema.UnresolvedReference; set => this.Schema.UnresolvedReference = value; }
+        public bool Is<T>()
+            where T : AvroSchema
+        {
+            return this.schema is T;
+        }
+
+        public Type GetSchemaType()
+        {
+            return this.schema.GetType();
+        }
+
+        public bool UnresolvedReference { get => this.schema.UnresolvedReference; set => this.schema.UnresolvedReference = value; }
 
-        public AsyncApiReference Reference { get => this.Schema.Reference; set => this.Schema.Reference = value; }
+        public AsyncApiReference Reference { get => this.schema.Reference; set => this.schema.Reference = value; }
 
         public void SerializeV2(IAsyncApiWriter writer)
         {
@@ -47,7 +60,7 @@ public void SerializeV2(IAsyncApiWriter writer)
 
         public void SerializeV2WithoutReference(IAsyncApiWriter writer)
         {
-            this.Schema.SerializeV2(writer);
+            this.schema.SerializeV2(writer);
         }
     }
 }

test/LEGO.AsyncAPI.Tests/Models/AsyncApiMessage_Should.cs

@@ -189,25 +189,23 @@ public void AsyncApiMessage_WithAvroSchemaFormat_Serializes()
 
             var message = new AsyncApiMessage();
             message.SchemaFormat = "application/vnd.apache.avro";
-            message.Payload = new AsyncApiAvroSchemaPayload()
+            var schema = new AvroRecord()
             {
-                Schema = new AvroRecord()
+                Name = "User",
+                Namespace = "com.example",
+                Fields = new List<AvroField>
                 {
-                    Name = "User",
-                    Namespace = "com.example",
-                    Fields = new List<AvroField>
+                    new AvroField()
                     {
-                        new AvroField()
-                        {
-                            Name = "username",
-                            Type = AvroPrimitiveType.String,
-                            Doc = "The username of the user.",
-                            Default = new AsyncApiAny("guest"),
-                            Order = AvroFieldOrder.Ascending,
-                        },
+                        Name = "username",
+                        Type = AvroPrimitiveType.String,
+                        Doc = "The username of the user.",
+                        Default = new AsyncApiAny("guest"),
+                        Order = AvroFieldOrder.Ascending,
                     },
                 },
             };
+            message.Payload = new AsyncApiAvroSchemaPayload(schema);
 
             // Act
             var actual = message.SerializeAsYaml(AsyncApiVersion.AsyncApi2_0);