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Testing File Attachment Processing in Paperclip

This test suite validates the AttachmentAdapter functionality in Paperclip, focusing on file handling, image processing, and attachment management. It ensures proper handling of file attributes, content types, and thumbnail generation for attachments in the Paperclip gem.

Test Coverage Overview

The test suite provides comprehensive coverage of the AttachmentAdapter class, examining core file handling capabilities and image processing features.

Tests file attribute handling including filename, size, and content type
Validates binary mode operations and file content integrity
Covers restricted filename character handling
Tests thumbnail generation and processing

Implementation Analysis

The testing approach utilizes RSpec’s context-based structure to organize related test scenarios logically. The implementation employs before/after hooks for proper test setup and cleanup, with careful attention to file handling and resource management.

Uses RSpec contexts to separate different testing scenarios
Implements proper file resource management
Validates both original files and processed thumbnails

Technical Details

RSpec testing framework
Paperclip gem integration
File I/O operations
MD5 hash digest verification
Temporary file handling
Binary mode file processing

Best Practices Demonstrated

The test suite exemplifies strong testing practices through proper resource cleanup, comprehensive edge case coverage, and thorough validation of file processing operations.

Proper file resource cleanup in after blocks
Comprehensive validation of file attributes
Edge case handling for restricted characters
Thorough content verification

thoughtbot/paperclip

spec/paperclip/io_adapters/attachment_adapter_spec.rb

            
require 'spec_helper'

describe Paperclip::AttachmentAdapter do
  before do
    rebuild_model path: "tmp/:class/:attachment/:style/:filename", styles: {thumb: '50x50'}
    @attachment = Dummy.new.avatar
  end

  context "for an attachment" do
    before do
      @file = File.new(fixture_file("5k.png"))
      @file.binmode

      @attachment.assign(@file)
      @attachment.save
      @subject = Paperclip.io_adapters.for(@attachment,
                                           hash_digest: Digest::MD5)
    end

    after do
      @file.close
      @subject.close
    end

    it "gets the right filename" do
      assert_equal "5k.png", @subject.original_filename
    end

    it "forces binmode on tempfile" do
      assert @subject.instance_variable_get("@tempfile").binmode?
    end

    it "gets the content type" do
      assert_equal "image/png", @subject.content_type
    end

    it "gets the file's size" do
      assert_equal 4456, @subject.size
    end

    it "returns false for a call to nil?" do
      assert ! @subject.nil?
    end

    it "generates a MD5 hash of the contents" do
      expected = Digest::MD5.file(@file.path).to_s
      assert_equal expected, @subject.fingerprint
    end

    it "reads the contents of the file" do
      expected = @file.read
      actual = @subject.read
      assert expected.length > 0
      assert_equal expected.length, actual.length
      assert_equal expected, actual
    end

  end

  context "for a file with restricted characters in the name" do
    before do
      file_contents = IO.read(fixture_file("animated.gif"))
      @file = StringIO.new(file_contents)
      @file.stubs(:original_filename).returns('image:restricted.gif')
      @file.binmode

      @attachment.assign(@file)
      @attachment.save
      @subject = Paperclip.io_adapters.for(@attachment,
                                           hash_digest: Digest::MD5)
    end

    after do
      @subject.close
    end

    it "does not generate paths that include restricted characters" do
      expect(@subject.path).to_not match(/:/)
    end

    it "does not generate filenames that include restricted characters" do
      assert_equal 'image_restricted.gif', @subject.original_filename
    end
  end

  context "for a style" do
    before do
      @file = File.new(fixture_file("5k.png"))
      @file.binmode

      @attachment.assign(@file)

      @thumb = Tempfile.new("thumbnail").tap(&:binmode)
      FileUtils.cp @attachment.queued_for_write[:thumb].path, @thumb.path

      @attachment.save
      @subject = Paperclip.io_adapters.for(@attachment.styles[:thumb],
                                           hash_digest: Digest::MD5)
    end

    after do
      @file.close
      @thumb.close
      @subject.close
    end

    it "gets the original filename" do
      assert_equal "5k.png", @subject.original_filename
    end

    it "forces binmode on tempfile" do
      assert @subject.instance_variable_get("@tempfile").binmode?
    end

    it "gets the content type" do
      assert_equal "image/png", @subject.content_type
    end

    it "gets the thumbnail's file size" do
      assert_equal @thumb.size, @subject.size
    end

    it "returns false for a call to nil?" do
      assert ! @subject.nil?
    end

    it "generates a MD5 hash of the contents" do
      expected = Digest::MD5.file(@thumb.path).to_s
      assert_equal expected, @subject.fingerprint
    end

    it "reads the contents of the thumbnail" do
      @thumb.rewind
      expected = @thumb.read
      actual = @subject.read
      assert expected.length > 0
      assert_equal expected.length, actual.length
      assert_equal expected, actual
    end

  end
end