Great topic, this one...
Our Sensei usually has repeated this several times; a test is a celebration of where you are in your training (both positive and negative, IMO).
He also points out that when asked to test, in his opinion you are allready at that level, though you can fail, he adds.
Last summer in Japan, HIS Sensei asked me to test for ikkyu. Maybe it was being there, but I had grown so accustomed to saying "Yes, Sensei." over the three weeks that before I knew it I had "agreed" to test. Oh man, was I freaked out.
Anyway, I passed the test, and when bowing to the rest of the class at the end, I was overwhelmed with gratitude towards them, as Michael points out above.
Test, exams and grading are all relevant anyway, IMO. It depends on the person, where they are in their training, if they have just joined a new club and have a new Sensei (which sounds like your case, Liane).
Marvin, if it's not too personal, were you asked to re-test due to a less-than-perfect first test, or was it due to changing style/teachers/federations?