public void AddExpressionSuccessWithGivenValidExpression()
{
var author = new Author(Guid.NewGuid().ToString(), _username, _fullName);
var expression = new Expression
{
Title = _title,
Pattern = _pattern,
Description = _description,
AuthorId = _authorId
};
author.AddExpression(expression);
Assert.Contains(author.Expressions, x => x == expression);
}