einarstensson/method-arguments-lab-001-prework-web

Method Arguments Lab

Objectives

1. Define a method that takes in an argument and uses that argument in the method body.
2. Define a method that takes in two arguments and uses both arguments in the method body.

Instructions

You'll be coding your methods in lib/introduction.rb.

The #introduction Method

Run the test suite to get started. Let's take a look at the first error:

Failures:

  1) #introduction takes in an argument of a name and puts out a phrase with that name using string interpolation
     Failure/Error: expect{introduction("Josh")}.to output("Hi, my name is Josh.\n").to_stdout
     NoMethodError:
       undefined method `introduction' for #<RSpec::ExampleGroups::Introduction:0x007fdbc499a938>
     # ./spec/introduction_spec.rb:5:in `block (3 levels) in <top (required)>'
     # ./spec/introduction_spec.rb:5:in `block (2 levels) in <top (required)>'

Wow, that's a lot of information. The important part for us though is the line that tells us what kind of error we are experiencing:

NoMethodError:
       undefined method `introduction'

Looks like our test is expecting to test a method called #introduction. Let's define that method in lib/introduction.rb.

# lib/introduction.rb

def introduction
end

Now we'll run our test suite again. You should see the following error:

Failures:

  1) #introduction takes in an argument of a name and puts out a phrase with that name using string interpolation
     Failure/Error: expect{introduction("Josh")}.to output("Hi, my name is Josh.\n").to_stdout
     ArgumentError:
       wrong number of arguments (1 for 0)
     # ./lib/introduction.rb:9:in `introduction'
     # ./spec/introduction_spec.rb:5:in `block (3 levels) in <top (required)>'
     # ./spec/introduction_spec.rb:5:in `block (2 levels) in <top (required)>'

Once again the important part of this error message is the part where the type of error is described:

ArgumentError:
       wrong number of arguments (1 for 0)

Now we have an ArgumentError. The test is trying to call our #introduction method with an argument (notice it says 1) but we haven't defined our method to take in any arguments, the for 0 part of the error message.

Let's fix that now:

# lib/introduction.rb

def introduction(name)
end

Run the test again and you'll see the following:

Failures:

  1) #introduction takes in an argument of a name and puts out a phrase with that name using string interpolation
     Failure/Error: expect{introduction("Josh")}.to output("Hi, my name is Josh.\n").to_stdout
       expected block to output "Hi, my name is Josh.\n" to stdout, but output nothing
       Diff:
       @@ -1,2 +1 @@
       -Hi, my name is Josh.
       
     # ./spec/introduction_spec.rb:5:in `block (2 levels) in <top (required)>'

Now the important part of our error message is here:

expected block to output "Hi, my name is Josh.\n" to stdout, but output nothing

Our test is expecting our method to puts out the exact phrase, using the value of the name argument that the method is called with.

Let's fix that:

# lib/introduction.rb

def introduction(name)
  puts "Hi, my name is #{name}."
end

Run the test again and we should be passing the first of our two tests. Use the test output and the procedure we just followed to get the second test passing.

The #introduction_with_language Method

Define a method, #introduction_with_language that takes in two arguments, name and language and outputs the phrase: `"Hi, my name is #{name} and I am learning to program in #{language}."