02.2.txt

2.2  Hello RSpec

Create a file named greeter_spec.rb anywhere on your system, open it in 
your favorite text editor, and type the following code:

Download hello/1/greeter_spec.rb

Line 1  describe "RSpec Greeter" do
2  it "should say 'Hello RSpec!' when it receives the greet() 
message" do
3  greeter = RSpecGreeter.new
4  greeting = greeter.greet
5  greeting.should == "Hello RSpec!"
6  end
7  end

We’ll get into all the details of this later in the book, but briefly 
here’s an explanation.

We start by declaring an example group using the describe( ) method on line 
1. On line 2, we declare an example using the it( ) method.

Within  the  example,  we  initialize  a  new  RSpecGreeter  on  line  3.  
This
is the Given  in this example:  the context that we set up and take for 
granted as a starting point.
On  line  4,  we  assign  the  value  returned  by  the  greet( )  method  
to  a greeting variable. This is the When in this example: the action that 
we’re focused on.


3.  http://groups.google.com/group/cukes
 

Lastly, on line 5, we set an expectation that the value of greeting should 
equal  “Hello  RSpec!”  This  is  the  Then  of  this  example:  the  
expected outcome.

As you’ll see throughout this book, we use these three simple words— Given, 
When, and Then—because they are easily understood by both technical and 
nontechnical contributors to a project.

Now save the file, open a command shell, cd into the directory in which
it is saved, and type this command:

rspec greeter_spec.rb

You should see output including this in the shell:

uninitialized constant RSpecGreeter

This  is  RSpec  telling  you  that  the  example  failed  because  there  
is  no
RSpecGreeter  class defined yet. To keep things simple, let’s just define
it in the same file. Adding this definition, the entire file should look 
like this:

Download hello/2/greeter_spec.rb

class RSpecGreeter
def greet
"Hello RSpec!"
end end

describe "RSpec Greeter" do
it "should say 'Hello RSpec!' when it receives the greet() message" do
greeter = RSpecGreeter.new greeting = greeter.greet greeting.should == 
"Hello RSpec!"
end end

Run the file again by typing rspec greeter_spec.rb, and the output should 
be something like this:

.

Finished in 0.00075 seconds
1 example, 0 failures

Success! The dot on the first line represents the one example that was run, 
and the summary on the last line reports that there was one exam- ple and 
zero failures.

This is a bit different from the Hello World examples we’re used to seeing
in programming language books because it doesn’t actually print Hello RSpec 
 to the command line. In this case, the feedback we get tells us the 
example ran and the code works as expected.