public async Task CheckUserByEmail()
{
//Arrange
var accounts = await userProvider.AccountsAsync();
Account account = accounts.FirstOrDefault();
//Act
var usersByEmail = await userProvider.GetByEmailAsync(account.Email);
//Assert
Assert.IsType <List <User> >(usersByEmail);
}//done
public Task <ICollection <Account> > AccountsAsync()
{
return(provider.AccountsAsync());
}