I'm not sure if you are talking from a performance perspective or a conceptual perspective, but this provides a useful discussion on multiple assertions:
My 2 cents is that multiple assertions are legitimate, as long as they prove a singluar assumption. Hence (as per the test on that page), this is a valid use of multiple assertions:
[Test]
public void ValueIsInRange()
{
int value = GetValueToTest();
Assert.That(value, Is.GreaterThan(10), "value is too small");
Assert.That(value, Is.LessThan(100), "value is too large");
}
[Edit] Thanks for the link. I have a whole bunch of comments in there to upvote. Guess my evening is planned :) [Edit]
I would also like to point out that ranges, like the one in your example, are almost always a symptom of an unstable test to begin with. I'd want to know why you're providing a range. Does the test blow up if another server is running tests at the same time? Let's fix that so the tests actually fail when there is a failure.
Now, there are lots of matchers that misbehave for corner case inputs, and an assert like "Make sure there's text, that it's a number, and that the number equals 10" may be necessary in order to prove that "10" appears, especially when you invert the test an say "Make sure the number isn't 10". And in this case I would say "write us a better matcher so that everyone can benefit from you figuring out how to do this".
This should go without saying, but I feel I have to repeat it every time there's an audience:
Green is not the end goal of testing. Red when there is an actual problem is the end goal of testing. Anything else is a very expensive way to consume resources.
That's two asserts, and yes you are essentially testing the same concept, which I'm comfortable with as long as it's not a regular thing. People go through all sorts of gymnastics to convince themselves "it's one thing" and I find it exhausting, especially since fixing the problem is usually easier than the rationalizing.
If multiple asserts is a regular thing, you can either start breaking down your tests, or write a custom matcher. The custom matcher gives you better diagnostics when it breaks, so is probably the way to go.
http://programmers.stackexchange.com/questions/7823/is-it-ok...
My 2 cents is that multiple assertions are legitimate, as long as they prove a singluar assumption. Hence (as per the test on that page), this is a valid use of multiple assertions: