diff --git a/test/Application.UnitTests/Services/DomainService/AccountServiceTests.cs b/test/Application.UnitTests/Services/DomainService/AccountServiceTests.cs
new file mode 100644
index 0000000..d1e01fd
--- /dev/null
+++ b/test/Application.UnitTests/Services/DomainService/AccountServiceTests.cs
@@ -0,0 +1,165 @@
+using Application.DTOs.Account;
+using Application.Interfaces.Repositories;
+using Application.Interfaces.Services;
+using Application.Mappers;
+using Application.Services.DomainService;
+using Application.Services.SharedService;
+using Domain.Entities;
+using NSubstitute;
+
+namespace test.Application.UnitTests.Services.DomainService;
+
+public class AccountServiceTests
+{
+    private readonly IAccountRepository _accountRepository;
+    private readonly AccountService _accountService;
+    private readonly ICsvReaderService _csvReaderService;
+
+    public AccountServiceTests()
+    {
+        _accountRepository = Substitute.For<IAccountRepository>();
+        _csvReaderService = Substitute.For<ICsvReaderService>();
+        _accountService = new AccountService(_accountRepository, _csvReaderService);
+    }
+    
+    [Fact]
+    public async Task AddAccountsFromCsvAsync_WhenCsvIsValid_ReturnsOk()
+    {
+        // Arrange
+        var filePath = "dummy.csv";
+        var accountCsvModels = new List<AccountCsvModel>
+        {
+            new AccountCsvModel
+            {
+                AccountID = 1,
+                CardID = 100,
+                IBAN = "IBAN1",
+                AccountType = "Savings",
+                BranchTelephone = "1234567890",
+                BranchAdress = "Main Street",
+                BranchName = "Main Branch",
+                OwnerName = "Mobin",
+                OwnerLastName = "Barfi",
+                OwnerID = 101
+            },
+            new AccountCsvModel
+            {
+                AccountID = 2,
+                CardID = 200,
+                IBAN = "IBAN2",
+                AccountType = "Checking",
+                BranchTelephone = "0987654321",
+                BranchAdress = "Some Street",
+                BranchName = "Some Branch",
+                OwnerName = "Mohammad",
+                OwnerLastName = "Mohammadi",
+                OwnerID = 102
+            }
+        };
+        var existingAccountIds = new List<long> { 1 };
+
+        _csvReaderService.ReadFromCsv<AccountCsvModel>(filePath).Returns(accountCsvModels);
+        _accountRepository.GetAllIdsAsync().Returns(existingAccountIds);
+
+        // Act
+        var result = await _accountService.AddAccountsFromCsvAsync(filePath);
+
+        // Assert
+        Assert.True(result.Succeed);
+        await _accountRepository
+            .Received(1)
+            .CreateBulkAsync(Arg.Is<List<Account>>(a =>
+                a.Count == 1 
+                && a.First().AccountId == 2
+                && a.First().OwnerName == "Mohammad"));
+    }
+
+    [Fact]
+    public async Task AddAccountsFromCsvAsync_WhenExceptionIsThrown_ReturnsFail()
+    {
+        // Arrange
+        var filePath = "dummy.csv";
+        _csvReaderService
+            .When(x => x.ReadFromCsv<AccountCsvModel>(filePath))
+            .Do(x => { throw new Exception("CSV read error"); });
+
+        // Act
+        var result = await _accountService.AddAccountsFromCsvAsync(filePath);
+
+        // Assert
+        Assert.False(result.Succeed);
+        Assert.Contains("An unexpected error occurred: CSV read error", result.Message);
+    }
+
+    [Fact]
+    public async Task GetAccountByIdAsync_WhenAccountExists_ReturnsAccount()
+    {
+        // Arrange
+        var accountId = 1;
+        var account = new Account { AccountId = accountId, OwnerName = "John Doe" };
+
+        _accountRepository.GetByIdAsync(accountId).Returns(account);
+
+        // Act
+        var result = await _accountService.GetAccountByIdAsync(accountId);
+
+        // Assert
+        Assert.NotNull(result);
+        Assert.Equal(accountId, result.Value!.AccountId);
+        Assert.Equal("John Doe", result.Value!.OwnerName);
+    }
+
+    [Fact]
+    public async Task GetAccountByIdAsync_WhenAccountDoesNotExist_ReturnsNull()
+    {
+        // Arrange
+        var accountId = 1;
+        _accountRepository.GetByIdAsync(accountId).Returns((Account?)null);
+
+        // Act
+        var result = await _accountService.GetAccountByIdAsync(accountId);
+
+        // Assert
+        Assert.False(result.Succeed);
+        Assert.Null(result.Value);
+        Assert.Equal("Account not found", result.Message);
+    }
+
+    [Fact]
+    public async Task GetAllAccountsAsync_WhenAccountsExist_ReturnsListOfAccounts()
+    {
+        // Arrange
+        var accounts = new List<Account>
+        {
+            new Account { AccountId = 1, OwnerName = "Mobin Barfi" },
+            new Account { AccountId = 2, OwnerName = "Mohammad Mohammadi" }
+        };
+
+        _accountRepository.GetAllAccounts().Returns(accounts);
+
+        // Act
+        var result = await _accountService.GetAllAccountsAsync();
+
+        // Assert
+        Assert.True(result.Succeed);
+        Assert.Equal(2, result.Value.Count);
+        Assert.Equal("Mobin Barfi", result.Value[0].OwnerName);
+        Assert.Equal("Mohammad Mohammadi", result.Value[1].OwnerName);
+    }
+
+    [Fact]
+    public async Task GetAllAccountsAsync_WhenExceptionIsThrown_ReturnsFail()
+    {
+        // Arrange
+        _accountRepository
+            .When(x => x.GetAllAccounts())
+            .Do(x => throw new Exception("Database error"));
+
+        // Act
+        var result = await _accountService.GetAllAccountsAsync();
+
+        // Assert
+        Assert.False(result.Succeed);
+        Assert.Equal("An unexpected error occurred: Database error", result.Message);
+    }
+}
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