public void TesBuildExpression()
{
var options = new SearchOptions <User> (new PageParameter {
SearchKey = "2"
});
options.ContainsFor(u => u.UserName)
.StartsFor(u => u.DepName)
.EndsFor(u => u.DepName);
var exp = options.BuildExpression();
output.WriteLine(exp.ToString());
Assert.NotNull(exp);
var query = TestDbContext.UseSqlite().Users.Where(exp);
Assert.NotEmpty(query);
output.WriteLine(query.ToQueryString());
}