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Project: Aruba

Publisher: Mark Ayers

Report disk usage

Sometimes you need to check, what amount of disk space a file consumes.

This is useful, since many tiny files will usually take up a lot more disk
space than their sizes suggest.

While not be very accurate, '#disk_usage helps estimate this "real"
allocated size on disk.

NOTE 1: currently "directories" are NOT supported.

NOTE 2: Aruba assumes the 'physical block size' is 512 bytes. (It usually is).

If your OS/filesystem doesn't report the number of blocks used (and your
allocation unit size is not 4096 bytes), you can change the default "block
size" Aruba uses for calculations:

E.g. for a 32kB "allocation unit size" and 16 blocks used for a tiny file
(check File::Stat.blocks reported by Ruby), just divide the
two numbers to get the "physical block size" you need to set:

Aruba.configure { |config| config.physical_block_size = 32_768 / 16 }.

We're gonna use the (correct) IEC-notation
(https://en.wikipedia.org/wiki/Binary_prefix) here:

* kilo => kibi
* mega => mebi
* giga => gibi

Background
Given
I use a fixture named "cli-app"
Scenarios
  1. Show disk usage for file
  2. Show disk usage for multiple files
  3. Convert reported disk usage to KibiByte
  4. Convert reported disk usage to MebiByte
  5. Convert reported disk usage to GibiByte
  6. Compare two repored disk usages
Show disk usage for file
Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file) { 'file.txt' }

  before(:each) do 
    write_file file, 'a'
  end

  let(:size_of_single_block) { File::Stat.new(expand_path(file)).blksize }

  it { expect(disk_usage(file)).to eq size_of_single_block }
end
When
I run rspec
Then
the specs should all pass
Show disk usage for multiple files

#disk_usage creates the sum of all given objects' sizes.

Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file1) { 'file1.txt' }
  let(:file2) { 'file2.txt' }

  before(:each) do 
    write_file file1, 'a'
    write_file file2, 'a'
  end

  let(:size_of_single_block) { File::Stat.new(expand_path(file1)).blksize }

  it { expect(disk_usage(file1, file2)).to eq size_of_single_block * 2 }
  it { expect(disk_usage([file1, file2])).to eq size_of_single_block * 2 }
end
When
I run rspec
Then
the specs should all pass
Convert reported disk usage to KibiByte
Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file) { 'file.txt' }

  before(:each) do 
    write_file file, 'a'
  end

  let(:converted_size) { File::Stat.new(expand_path(file)).blksize.to_f / 1_024 }

  it { expect(disk_usage(file).to_kibi_byte).to eq converted_size }
end
When
I run rspec
Then
the specs should all pass
Convert reported disk usage to MebiByte
Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file) { 'file.txt' }

  before(:each) do 
    write_file file, 'a'
  end

  let(:converted_size) { File::Stat.new(expand_path(file)).blksize.to_f / 1_024 / 1024 }

  it { expect(disk_usage(file).to_mebi_byte).to eq converted_size }
end
When
I run rspec
Then
the specs should all pass
Convert reported disk usage to GibiByte
Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file) { 'file.txt' }

  before(:each) do 
    write_file file, 'a'
  end

  let(:converted_size) { File::Stat.new(expand_path(file)).blksize.to_f / 1_024 / 1_024 / 1_024 }

  it { expect(disk_usage(file).to_gibi_byte).to eq converted_size }
end
When
I run rspec
Then
the specs should all pass
Compare two repored disk usages
Given
a file named "spec/disk_usage_spec.rb" with: 
require 'spec_helper'

RSpec.describe 'disk usage', :type => :aruba do
  let(:file1) { 'file1.txt' }
  let(:file2) { 'file2.txt' }

  before(:each) do 
    write_file file1, 'a' * 10_000
    write_file file2, 'a'
  end

  before :each do
    @size1 = disk_usage(file1)
    @size2 = disk_usage(file2)
  end

  it { expect(@size1).to be > @size2 }
end
When
I run rspec
Then
the specs should all pass

Last published about 3 years ago by philoserf.