public void Ctor_ValidPostId_ReturnsExpected()
{
var postRequest = new PostRequest("PostId");
Assert.Equal("PostId", postRequest.PostId);
Assert.Null(postRequest.Fields);
Assert.Equal("/PostId?fields=id,message,link,caption,description,from,created_time," +
"updated_time,permalink_url,status_type,type,name,place,shares," +
"comments.limit(0).summary(True),reactions.limit(0).summary(True)&", postRequest.ToString());
}