public async Task ExpectAddExpenseAsync(string accountName, decimal amount, string category, string subcategory, Action <Expense> modEx = null, Action <CreateExpenseCommand> modCmd = null, HttpStatusCode expectedStatus = HttpStatusCode.OK)
{
var expense = new Expense(amount, category, subcategory)
{
Date = DateTime.Now.Date
};
modEx?.Invoke(expense);
var cmd = expense.AsCommand(accountName);
modCmd?.Invoke(cmd);
(await this.Client.PostAsync($"/api/account/{accountName}/expenses", cmd.AsContent())).StatusCode.Should().Be(expectedStatus);
}