Cucumber and variables internal to methods called indirectly - ruby

Question

Please note: I am new to TDD & cucumber, so the answer may be very easy.
I am creating a basic image editor for a test (the image is just a sequence of letters).
I have written a Cucumber story:
Scenario Outline: edit commands
Given I start the editor
And a 3 x 3 image is created
When I type the command <command>
Then the image should look like <image>
The step
Scenarios: colour single pixel
| command | image |
| L 1 2 C | OOOCOOOOO |
always fails, returning
expected: "OOOCOOOOO"
got: " OOOOOOOO" (using ==) (RSpec::Expectations::ExpectationNotMetError)
This is the step code:
When /^I type the command (.*)$/ do |command|
#editor.exec_cmd(command).should be
end
The function exec_cmd in the program recognizes the command and launches the appropriate action. In this case it will launch the following
def colorize_pixel(x, y, color)
if !#image.nil?
x = x.to_i
y = y.to_i
pos = (y - 1) * #image[:columns] + x
#image[:content].insert(pos, color).slice!(pos - 1)
else
#messenger.puts "There's no image. Create one first!"
end
end
However, this always fails unless I hardcode the values of the two local variables (pos and color) in the function in the program itself.
Why? It doesn's seem I'm doing anything wrong in the program itself: the function does what it's supposed to do and those two variables are only useful locally. So I'd think this is a problem with my use of cucumber. How do I properly test this?
---edit---
def exec_cmd(cmd = nil)
if !cmd.nil?
case cmd.split.first
when "I" then create_image(cmd[1], cmd[2])
when "S" then show_image
when "C" then clear_table
when "L" then colorize_pixel(cmd[1], cmd[2], cmd[3])
else
#messenger.puts "Incorrect command. " + "Commands available: I C L V H F S X."
end
else
#messenger.puts "Please enter a command."
end
end

Answer 1

When /^I type the command (.*)$/ do |command|
#output = #editor.exec_cmd(command)
end
Then /^the image should look like (.)*$/ do |expected_image|
#output.should == expected_image
end
Hope this may help you.

Answer 2

It's not a cucumber issue.
The problem was that, in exec_cmd, split was called only in the "case" clause, not in the "when"s. This meant that, since the command's format was "a 1 2 b", cmd[1] in the "when" would call the second character of the string, a space, not the second value of the array, and the other functions would convert that to_i, returning 0.
I changed exec_cmd like this:
def exec_cmd(cmd = nil)
if !cmd.nil?
cmd = cmd.split
case cmd.first
when "I" then create_image(cmd[1], cmd[2])
[...]
end
which fixed the issue.