0: Red

/Users/casiano/local/src/ruby/LPP/rspec_examples/rpcalculator/
|~lib/
| `~math/
|   `-rpcalc.rb
|~spec/
| `~math/
|   `-rpcalc_spec.rb
|-Rakefile
`-README.md

[~/local/src/ruby/LPP/rspec_examples/rpcalculator]$ cat spec/math/rpcalc_spec.rb 
module Math
  describe RPCalc do

  end
end

We use the describe( ) method to define an example group. The class or string we pass to it represents the facet of the system that we want to describe (a new account). The block holds the code examples that make up that group.

[~/local/src/ruby/LPP/rspec_examples/rpcalculator]$ rspec spec/math/rpcalc_spec.rb 
/Users/casiano/local/src/ruby/LPP/rspec_examples/rpcalculator/spec/math/rpcalc_spec.rb:2:
in `<module:Math>': uninitialized constant Math::RPCalc (NameError)