Doubt regarding Testing with RSpec

Hi all,

I have a library of RSpec Test examples. Now, from an upper ruby layer, I
need to run only individual separate test example from the library that
matches a particular string in the upper layer.

For Example:

My RSpec library file contains many test examples like:

*describe arithmetic do

it "should provide a sum of two numbers" do
(1 + 2).should == 3

it "should provide a difference of two numbers" do
(5-4).should == 1



*Now there is a ruby layer above from where I need to run the first test i.e
when my *input is test_add* the * it "should provide a sum of two
numbers"*must only run and give me results of test.
Similarly, if in the input I am accepting in my upper ruby code is *
test_subtract*, the 2nd test must run * (it "should provide a difference of
two numbers")* and show the result of test.

Is this possible with RSpec ?

Thanks in advance,