- Define a method that takes in an argument and pass a variable in as that argument.
- Understand that a variable defined inside a method cannot be used outside of that method.
Open up lib/catch_phrase.rb
. You should see the following method:
def catch_phrase
puts phrase
end
Note that the method is trying to puts
out a variable called phrase
.
Let's take a look at the test for this method in spec/catch_phrase_spec.rb
:
describe "#catch_phrase" do
it "puts out a catch phrase" do
phrase = "It's-a me, Mario!"
expect{catch_phrase}.to output("It's-a me, Mario!\n").to_stdout
end
end
Go ahead and run the test for this method only by typing spec/catch_phrase_spec.rb
into your terminal in the directory of this lab. You should see the following error:
NameError:
undefined local variable or method `phrase' for #<RSpec::ExampleGroups::CatchPhrase:0x007f87b9cf04c0>
This error is occuring because the code inside the #catch_phrase
method is trying to use the phrase
variable but we defined this variable on line 27 of our test. In other words, this variable is being defined outside of the method. Our method doesn't have access to it! It is out of scope. Let's fix it!
We need to pass phrase
into our #catch_phrase
as an argument. Let's do it:
- Re-define the
#catch_phrase
method to take in an argument of a phrase. - Change the test in
spec/catch_phrase_spec.rb
to match the following:
require "spec_helper"
describe "#catch_phrase" do
it "puts out a catch phrase" do
phrase = "It's-a me, Mario!"
expect{catch_phrase(phrase)}.to output("It's-a me, Mario!\n").to_stdout
end
end
Open up lib/rescue_princess_peach.rb
and take a look at the following method:
def rescue_princess_peach
status = "rescued"
puts "Hooray! Mario has rescued Princess Peach."
end
Notice that the body of this method is setting a variable, status
equal to a value of "rescued"
. Do you think we will be able to access this variable outside of the method? Let's find out!
1 . Comment back in the follow lines in your lib/rescue_princess_peach.rb
file:
rescue_princess_peach
puts status
2 . Run the file with ruby lib/rescue_princess_peach.rb
in your terminal. You should see the following:
Hooray! Mario has rescued Princess Peach.
lib/rescue_princess_peach.rb:12:in `<main>': undefined local variable or method `status' for main:Object (NameError)
We are getting a NameError because status
is undefined. Wait a minute, you might be wondering. Didn't we define status
instide the #rescue_princess_peach
method? We did, but variables defined inside a method are not available outside of that method.
Run the test suite and you'll see that we are passing all of our tests. If you open up the spec/rescue_princess_peach_spec.rb
file, you'll see the following test:
require "spec_helper"
describe "#rescue_princess_peach" do
it "outputs a message and sets a variable, status, that is not available outside of this method" do
expect{rescue_princess_peach}.to output("Hooray! Mario has rescued Princess Peach.\n").to_stdout
expect{puts status}.to raise_error(NameError)
end
end
Notice the last expectation of our test: expect{puts status}.to raise_error(NameError)
. We expect any attempt to use the status
variable to be met with a NameError
. Our program, outside of the #rescue_princess_peach
method, just doesn't know what it is.