Microsoft SDE interview

Yesterday, I returned from Ithaca, NY(Cornell University). I went there to give Microsoft On-site interview for SDE(Software Design Engineer) position. This was by far the best interview process that I experienced.
Everything happened so fast just within 2 weeks, I cleared preliminary interview over phone which roughly went for 45 minutes.They asked some puzzles, one testing question and one algorithm related question and my projects and previous work experiences.
On Sunday, got an email from Microsoft people stating they have a slot opened on Thursday and I said yes since I don't want to wait a month or two to again visit Redmond headquarters. I was preparing for this interview for last 2 weeks after giving preliminary interview since I knew it went very well and I would be called for on-site interview.
Interview day went like a breeze, only three interviews which consist of one testing and two programming/ algorithm puzzles. In Testing interview, I struggled a lot since I could not assimilate points under sections and I was just giving answers in a very haphazard manner but they were quite right and pertinent to the problem given to me.
Then, 2nd and 3rd interviews were programming, to be specific algorithms related, I impressed interviewers a lot by not only giving more than one solution to the problem but also telling them the algorithm complexities of each one of them in terms of Big-Oh, they were pretty impressed with my conceptual knowledge, I was satisfied since I am convincing people who are Design Engineer Leads at Microsoft for past 12-20 years and graduates of Cornell University(Top 10 Computer Science University in United States). I little bit struggled in writing code, like simulating Hashtable in Java/C# in C++ by constructing a look-up array but somehow managed to make it. After giving these two programming interviews I realized I haven't done any testing on my code and then I realized that I am going to go home empty handed. Testing like empty string and empty array conditions and all.
I was very much satisfied with how my interviews went and was hoping positive outcome. As day passed morning turned to afternoon roughly at 1 PM, one of the managers came to me and he took me to the lobby and told me right now, they won't be selecting me and he was generous enough to give me the feedback, he told the conceptual knowledge of mine was pretty impressive but I suck at testing and in some part I struggled while writing code, they were so right and they are so great they assessed what was in my mind and told me.
Anyway, I am very happy since after this interview I feel so good since I prepared very hard, got many things/concepts cleared and did a lot of problem solving stuff, feels like brain has started working in a very right way :). This was the last time I appeared for Microsoft Interview as a Campus candidate but feeling very gratified with my own personal performance when compared to last on-site interview of Microsoft I gave at Redmond.