PdfSpec includes rspec matchers to compare the appearance of PDF files. This is obviously most useful when you need to verify that you can produce a PDF that looks identical to a sample PDF file.

This library depends on the rmagick ruby gem.

brew install imagemagick
brew install ghostscript

sudo port install ImageMagick

The following was tested on Ubuntu 11.10, 12.04, and 20.04.

sudo apt-get install libmagickwand-dev

On Ubuntu 20.04 and later, you may run into the following error:

Magick::ImageMagickError:
   attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/408

To resolve this, edit /etc/ImageMagick-6/policy.xml. Change <policy domain="coder" rights="none" pattern="PDF" /> to <policy domain="coder" rights="read|write" pattern="PDF" />. If that doesn't help, change <!-- <policy domain="module" rights="none" pattern="{PS,PDF,XPS}" /> --> to <policy domain="module" rights="read|write" pattern="{PS,PDF,XPS}" />.

# Install libmagickwand

To use the matchers in your tests, simple include the Matchers module into RSpec:

RSpec.configure do |config|
  config.include(PdfSpec::Matchers)
end

Or include it in certain tests:

describe "Testing PDFs" do
  include PdfSpec::Matchers

  it "should match..."; end
end

Matchers contains the have_same_pdf_appearance_as expectation which will render out PDF files to pixel buffers in memory and then compare them pixel by pixel.

it "should be the same PDF" do
  source_pdf = File.read("path/to/source")
  expected_pdf = File.read("path/to/expected")

  source.should have_same_pdf_appearance_as(expected_pdf)
end