Unit testing the code that is written using repository pattern

Question

I have implemented my business logic using the repository pattern. I have an Approve method in my controller. I am calling the service method ApproveUserChangeRequest, which in turn invokes GetUserChangeRequest and ApproveUserChangeRequest in the UnitofWork class. I would like to know if this is standard practice or if there are better ways of doing it. Please bear in mind in to test the service methods.

UserConroller

[HttpPost]
[AllowAnonymous]
[Route("approve-change-request")]
public IActionResult ApproveUserChangeRequest([FromBody] ApproveUserChangeRequests approveUserChangeRequests)
{
    if (!ModelState.IsValid)
    {
        return BadRequest(new ResponseModel()
        {
            ResponseMessages = new Dictionary<string, string[]>
            {
                { "Errors", ModelState.Values.SelectMany(x => x.Errors).Select(x => x.ErrorMessage).ToArray() }
            }
        });
    }    

    var result  = _userService.ApproveUserChangeRequest(approveUserChangeRequests);
    var message = string.Empty;
    if (result.Succeeded)
    {
        return Ok(new ResponseModel()
        {
            ResponseMessages = new Dictionary<string, string[]>
            {
               { "Info", new string[] { $"True" } }
            }
        });
    }
    message = string.Join(";", result.Errors.Select(x => $"Code: {x.Code}. Description: {x.Description}"));
    _logger.Error(new IdentityException($"Error approving user change requests. Message: {message}"));
    return BadRequest();

}

UserService class

public  IdentityResult ApproveUserChangeRequest(ApproveUserChangeRequests approveUserChangeRequests)
{
    var userChangeRequest = _userUow.GetUserChangeRequest(approveUserChangeRequests.UserChangeRequestID);

    IdentityResult result =  _userUow.ApproveUserChangeRequest(userChangeRequest, approveUserChangeRequests.ApprovedByAuthUserId, approveUserChangeRequests.AuthApplicationName);
    return result;
}    

UnitofWork class (uow)

public UserChangeRequest GetUserChangeRequest(int userChangeRequestId)
{
    return UserChangeRequestRepository.GetQueryable(x =>
        x.Id == userChangeRequestId)
        .FirstOrDefault();
}


  public IdentityResult ApproveUserChangeRequest(UserChangeRequest userChangeRequest, int approvedByAuthUserId, string authApplicationName)
{
    var idResult = IdentityResult.Success;

    // Check if UserChangeRequest is still Pending
    bool isUserChangeRequestPending = UserChangeRequestRepository.GetQueryable(x => x.Id == userChangeRequest.Id && x.ChangeStatus == "Pending").Any();

    if (isUserChangeRequestPending && approvedByAuthUserId > 0)
    {
        // Inserting record in the UserChangeRequestApproval table
        InsertUserChangeRequestApproval(userChangeRequest);
        SaveContext();

        //Updating the user details in IdentityDB, ClientCompanyContact and AuthUser tables 
        UpdateUserDetails(userChangeRequest, authApplicationName);
    }
    else
    {
        idResult = IdentityResult.Failed(new IdentityError { Description = "No userchange request to approve" });
    }
    return idResult;
}