Can I see registers after model test in Rails?

I'm new in Ruby on Rails and testing and I'm doign some model tests.

After using rails test command and the test passed, I made a query to the affected tables, but it's empty (there are only two empty registers but no the test ones).

My test code it's this:

test "sign up successful username-pw" do
    params =  { "username": "acme", "password": "foo123" }
    user = User.new(params)
    assert user.save
end

I'm worried about the results because I added in the seed file more registers but I can't see if really are used in the test (according with the results, they didn't).

Is it normal the empty test database or it's something that I'm not considering?

Thanks.