I want to run a block of code only for the first element of a array. I have the following code as of now

$data = YAML.load_file(yml_file_to_load)
    @Alarms = $data['Alarms']
    @Alarms.each do |alarm|
    
          describe "Test code is going start from here", :test do

This particular code run the block for every element in the array @Alarms. I want the code to run only for first element that is the code has to run only once.

Note that I also want to preserve the value of alarm variable inside the block. Here the variable should contain first element of array.

CodePudding user response：

When you only want to test the first element of the array then just assign the element to a variable, for example like this:

before do
  data = YAML.load_file(yml_file_to_load)
  @alarm = data['Alarms'][0]
end

describe "Test code is going start from here", :test do
  # use @alarm in the test

CodePudding user response：

You can use Object#tap to yield any object to a block:

$data = YAML.load_file(yml_file_to_load) # Why are you using a global?
@alarms = $data['alarms'] # variables should be snakecase
@alarms.first.tap do |alarm|
  # ...
end

tap returns the original object. So its useful when you're only interested in the side effects. If you want to use the return value of the block use then:

result = @alarms.first.then do |alarm|
  # ...
end