[#16] Unit tests

Signed-off-by: Pavel Gross <p.gross@yadro.com>

src/FrostFS.SDK.ModelsV2/Object/FrostFsObject.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Security.Cryptography;
+using FrostFS.SDK.ModelsV2.Enums;
+
+namespace FrostFS.SDK.ModelsV2;
+
+public class FrostFsObject
+{
+    public FrostFsObject(ObjectId objectId, ObjectHeader header, byte[] payload)
+    {
+        ObjectId = objectId;
+        Payload = payload;
+        Header = header;        
+    }
+
+    public FrostFsObject(ContainerId container, byte[] payload, ObjectType objectType = ObjectType.Regular)
+    {
+        Payload = payload;
+        Header = new ObjectHeader(containerId: container, type: objectType, attributes: []);        
+    }
+    
+    public ObjectHeader Header { get; set; }
+    
+    public ObjectId? ObjectId
+    {
+        get; internal set;
+    }
+    
+    public byte[] Payload { get; set; }
+
+    public IObjectReader? ObjectReader { get; set; }
+    
+    public Signature? Signature { get; set; }   
+
+    public void SetParent(LargeObject largeObject)
+    {
+        if (Header?.Split == null)
+            throw new Exception("The object is not initialized properly");
+
+        Header.Split.ParentHeader = largeObject.Header;
+    }
+}
+
+public class LargeObject(ContainerId container) : FrostFsObject(container, [])
+{
+    private readonly SHA256 payloadHash = SHA256.Create();
+
+    public void AppendBlock(byte[] bytes, int count)
+    {
+        Header!.PayloadLength += (ulong)count;
+        this.payloadHash.TransformBlock(bytes, 0, count, bytes, 0);
+    }
+
+    public LargeObject CalculateHash()
+    {
+        this.payloadHash.TransformFinalBlock([], 0, 0);
+        Header!.PayloadCheckSum = this.payloadHash.Hash;
+        return this;
+    }
+
+    public ulong PayloadLength
+    {
+        get { return Header!.PayloadLength; }
+    }
+}
+
+public class LinkObject : FrostFsObject
+{
+    public LinkObject(ContainerId containerId, SplitId splitId, LargeObject largeObject) : base (containerId, [])
+    {
+        Header!.Split = new Split(splitId)
+        {
+            ParentHeader = largeObject.Header
+        };
+    }
+}