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Testing Vips Image Processing Implementation in CarrierWave

This test suite validates the CarrierWave::Vips image processing functionality, focusing on image manipulation operations like resizing, cropping, and format conversion. The tests ensure reliable image processing capabilities while maintaining file integrity and handling various edge cases.

Test Coverage Overview

The test suite provides comprehensive coverage of image processing operations including:

Format conversion between image types
Multiple resize operations (fill, fit, limit, pad)
Dimension manipulation and validation
Cropping functionality
Error handling for invalid images

Implementation Analysis

The testing approach utilizes RSpec’s behavior-driven development patterns with shared file handling setup and teardown. Tests employ CarrierWave’s uploader base class with Vips integration, verifying image transformations through dimension checks and format validation.

Technical Details

Key technical components:

RSpec testing framework
Vips image processing library
MiniMagick for image validation
File manipulation utilities
I18n for error message localization

Best Practices Demonstrated

The test suite exemplifies testing best practices through:

Isolated test cases with proper setup/teardown
Comprehensive edge case coverage
Proper error handling validation
Internationalization testing
Clean test organization with descriptive contexts

carrierwaveuploader/carrierwave

spec/processing/vips_spec.rb

            
require 'spec_helper'

describe CarrierWave::Vips do
  let(:klass) { Class.new(CarrierWave::Uploader::Base) { include CarrierWave::Vips } }

  let(:instance) { klass.new }
  let(:landscape_file_path) { file_path('landscape.jpg') }
  let(:landscape_copy_file_path) { file_path('landscape_copy.jpg') }

  before do
    FileUtils.cp(landscape_file_path, landscape_copy_file_path)
    allow(instance).to receive(:cached?).and_return true
    allow(instance).to receive(:file).and_return(CarrierWave::SanitizedFile.new(landscape_copy_file_path))
  end

  after { FileUtils.rm(landscape_copy_file_path) if File.exist?(landscape_copy_file_path) }

  describe "#convert" do
    it "converts from one format to another" do
      instance.convert('png')
      expect(instance.file.extension).to eq('png')
      expect(instance).to be_format('png')
      expect(instance.file.content_type).to eq('image/png')
    end

    it "respects the page parameter" do
      # create a multi-layer image
      tiff = Tempfile.new(["file", ".tiff"])
      MiniMagick::Tool::Convert.new do |convert|
        convert.merge! [landscape_file_path, landscape_file_path, landscape_file_path]
        convert << tiff.path
      end

      allow(instance).to receive(:file).and_return(CarrierWave::SanitizedFile.new(tiff.path))

      instance.convert('png', 0)
      expect(instance.file.extension).to eq('png')
      expect(instance).to be_format('png')
      expect(instance.file.size).not_to eq(0)
    end
  end

  describe '#resize_to_fill' do
    it "resizes the image to exactly the given dimensions and maintain file type" do
      instance.resize_to_fill(200, 200)

      expect(instance).to have_dimensions(200, 200)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/jpeg/)
    end

    it "resizes the image to exactly the given dimensions and maintain updated file type" do
      instance.convert('png')
      instance.resize_to_fill(200, 200)

      expect(instance).to have_dimensions(200, 200)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/png/)
      expect(instance.file.extension).to eq('png')
    end

    it "scales up the image if it smaller than the given dimensions" do
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to_not include('Quality: 70')

      instance.resize_to_fill(1000, 1000, combine_options: { saver: { quality: 70 } })

      expect(instance).to have_dimensions(1000, 1000)
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to include('Quality: 70')
    end
  end

  describe '#resize_and_pad' do
    it "resizes the image to exactly the given dimensions and maintain file type" do
      instance.resize_and_pad(200, 200)

      expect(instance).to have_dimensions(200, 200)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/jpeg/)
    end

    it "resizes the image to exactly the given dimensions and maintain updated file type" do
      instance.convert('png')
      instance.resize_and_pad(200, 200)

      expect(instance).to have_dimensions(200, 200)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/png/)
    end

    it "scales up the image if it smaller than the given dimensions" do
      instance.resize_and_pad(1000, 1000)

      expect(instance).to have_dimensions(1000, 1000)
    end

    it "pads with black" do
      instance.resize_and_pad(200, 200)

      color_of_pixel(instance.current_path, 0, 0).tap do |color|
        expect(color).to include('#000000')
        expect(color).not_to include('none')
      end
    end

    it "pads with transparent" do
      instance.convert('png')
      instance.resize_and_pad(200, 200, nil, 'centre', true)

      expect(color_of_pixel(instance.current_path, 0, 0)).to include('none')
    end

    it "doesn't pad with transparent" do
      instance.resize_and_pad(200, 200, [255, 255, 255])
      instance.convert('png')

      color_of_pixel(instance.current_path, 0, 0).tap do |color|
        expect(color).to include('#FFFFFF')
        expect(color).not_to include('#FFFFFF00')
      end
    end

    it 'accepts combine_options and set quality' do
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to_not include('Quality: 70')

      instance.resize_and_pad(1000, 1000, combine_options: { saver: { quality: 70 } })

      expect(instance).to have_dimensions(1000, 1000)
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to include('Quality: 70')
    end

    it 'accepts non-argument option as combine_options' do
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to include('exif:ColorSpace: 1')

      instance.resize_and_pad(1000, 1000, combine_options: { saver: { strip: true } })

      expect(instance).to have_dimensions(1000, 1000)
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to_not include('exif:ColorSpace: 1')
    end
  end

  describe '#resize_to_fit' do
    it "resizes the image to fit within the given dimensions and maintain file type" do
      instance.resize_to_fit(200, 200)

      expect(instance).to have_dimensions(200, 150)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/jpeg/)
    end

    it "resizes the image to fit within the given dimensions and maintain updated file type" do
      instance.convert('png')
      instance.resize_to_fit(200, 200)

      expect(instance).to have_dimensions(200, 150)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/png/)
      expect(instance.file.extension).to eq('png')
    end

    it 'scales up the image if it smaller than the given dimensions and set quality' do
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to_not include('Quality: 70')

      instance.resize_to_fit(1000, 1000, combine_options: { saver: { quality: 70} })

      expect(instance).to have_dimensions(1000, 750)
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to include('Quality: 70')
    end
  end

  describe '#resize_to_limit' do
    it 'resizes the image to fit within the given dimensions, maintain file type and set quality' do
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to_not include('Quality: 70')

      instance.resize_to_limit(200, 200, combine_options: { saver: { quality: 70} })

      expect(instance).to have_dimensions(200, 150)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/jpeg/)
      expect(::MiniMagick::Tool::Identify.new.verbose(instance.current_path).call).to include('Quality: 70')
    end

    it "resizes the image to fit within the given dimensions and maintain updated file type" do
      instance.convert('png')
      instance.resize_to_limit(200, 200)

      expect(instance).to have_dimensions(200, 150)
      expect(::Vips::Image.new_from_file(instance.current_path).get("vips-loader")).to match(/png/)
      expect(instance.file.extension).to eq('png')
    end

    it "doesn't scale up the image if it smaller than the given dimensions" do
      instance.resize_to_limit(1000, 1000)

      expect(instance).to have_dimensions(640, 480)
    end
  end

  describe "#crop" do
    it "extracts an area defined from the left and top positions, with the given width and height" do
      instance.crop(70, 40, 500, 400)
      expect(instance).to have_dimensions(500, 400)
    end

    it "retains original image boundary if either edge of the cropping box falls outside it" do
      instance.crop(140, 80, 500, 480)
      expect(instance).to have_dimensions(500, 400)
    end
  end

  describe "#width and #height" do
    it "returns the width and height of the image" do
      instance.resize_to_fill(200, 300)

      expect(instance.width).to eq(200)
      expect(instance.height).to eq(300)
    end
  end

  describe '#dimension_from' do
    it 'evaluates procs' do
      instance.resize_to_fill(Proc.new { 200 }, Proc.new { 200 })

      expect(instance).to have_dimensions(200, 200)
    end

    it 'evaluates procs with uploader instance' do
      width_argument = nil
      width = Proc.new do |uploader|
        width_argument = uploader
        200
      end
      height_argument = nil
      height = Proc.new do |uploader|
        height_argument = uploader
        200
      end
      instance.resize_to_fill(width, height)

      expect(instance).to have_dimensions(200, 200)
      expect(instance).to eq(width_argument)
      expect(instance).to eq(height_argument)
    end
  end

  describe "test errors" do
    context "invalid image file" do
      before { File.open(instance.current_path, 'w') { |f| f.puts "bogus" } }

      it "fails to process a non image file" do
        expect { instance.resize_to_limit(200, 200) }.to raise_exception(CarrierWave::ProcessingError, /^Failed to manipulate, maybe it is not an image\?/)
      end

      it "uses I18n" do
        change_locale_and_store_translations(:nl, :errors => {
          :messages => {
            :processing_error => "Kon bestand niet bewerken, misschien is het geen beeld bestand?"
          }
        }) do
          expect {instance.resize_to_limit(200, 200)}.to raise_exception(CarrierWave::ProcessingError, /^Kon bestand niet bewerken, misschien is het geen beeld bestand?\?/)
        end
      end

      it "doesn't suppress errors when translation is unavailable" do
        change_locale_and_store_translations(:foo, {}) do
          expect { instance.resize_to_limit(200, 200) }.to raise_exception( CarrierWave::ProcessingError )
        end
      end

      context ":en locale is not available and enforce_available_locales is true" do
        it "doesn't suppress errors" do
          change_and_enforce_available_locales(:nl, [:nl, :foo]) do
            expect { instance.resize_to_limit(200, 200) }.to raise_exception(CarrierWave::ProcessingError)
          end
        end
      end
    end
  end
end