> It keeps them in the right set of mind: "How should objects in some
> contexts behave?" and not "what equality/difference/basic property/...
> should I test?".

Each context in rSpec is just a new testcase. For example,
EmptyStackTest's setup() can be written "@stack = Stack.new",
FullStackTest's steup() can be written "@stack = Stack.new;
@stack.fillup...."

so a rSpec file with 5 contexts is same as 5 unit testcase files,
although I almost always only write one testcase per class. if
assert_equal is ambiguous, you always can use assert(object.attr [== |
equal | eql] "expected")

>From my point of view, same testing tasks done in rSpec is not much
easier than using existing tools (Test/unit, rails testing tools).