I agree with waldnzwrld. that is not the porpus of this kata.

I love the idea of this kata, but I really felt your README let it down. It wasn't at all clear what methods the ORM is expected to make available.

The fact that records should only be saved to the 'database' when an explicit save message is sent, and not on instantiation, is pretty counter-intuitive.

How you come up with this formula?

That's not an issue.

Also you can always use variables to store results before checking, which allows you to evaluate the results in any order you want.

the ^ is a logical xor not a bitwise xor

You might want to remove your puts. ;-)

Thank you, I'm glad you liked it!

Nice Kata!

Good to see something that tests your skills as a structural programmer rather than just being good at maths.

BTW the same problem may occur in assert_not_equals(actual, expected...)

I'm curious, why is assert_equals implemented with (actual, expected) arguments and not (expected, actual) like in T::U. In one kata this caused a situation where modified original input caused some test cases to fail.

Oh well, my bad, sorry. Didn't think Codewars is using a custom test framework.
According to https://github.com/Codewars/kata-test-framework-ruby/blob/master/framework.rb#L147 real order is actual, expected, so you're right.
Now I'm curious why is it implemented this way.

According to rubydocs, it is not. http://ruby-doc.org/stdlib-2.1.0/libdoc/test/unit/rdoc/Test/Unit/Assertions.html#method-i-assert_equal

Correct order is expected, actual.

Thank you :)

Excellent kata. Although after submitting my cheating solution and reading intended one I feel disappointed I didn't make it "the right way". Still, enjoyed every second of it.