Common approach to verifying if something is empty

Question

I'm quite new to InSpec and would like to learn from your experience.

There are some approaches to verifying if a file or its property is empty.

Approach 1 - using file resource to and read its content. Use eq matcher to check the output ''

describe file('file_path') do
  its(:contents) { should eq ' ' }
end

Approach 2 - - using file resource to and read its content, but check null

describe file('file_path') do
  its(:contents) { should be nil }
end

Approach 3 (uncommon) - use command resource to execute the cat command

describe command('cat /etc/file_path') do
  its(:stdout) { should eq ' ' }
end

Approach 4 - use should be_empty

describe file('file_path') do
  its(:contents) { should be_empty }
end

If there is any more approach, please feel free to suggest.

Is there a performance impact if using uncommon approach?

Answer 1

Why not its(:size) { should eq 0 }? That avoids the need to actually transfer the contents.